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Analysis of the Causes of Ring-shaped Cracks in Quenched SAE 4140 Seamless Steel Pipe

October 17, 2024/in Industry Knowledge/by Energy Steel

The reason for the ring-shaped crack at the pipe end of the SAE 4140 seamless steel pipe was studied by chemical composition exam, hardness test, metallographic observation, scanning electron microscope, and energy spectrum analysis. The results show that the ring-shaped crack of SAE 4140 seamless steel pipe is a quenching crack, generally occurring at the pipe’s end. The reason for the quenching crack is the different cooling rates between the inside and outside walls, and the outside wall cooling rate is much higher than that of the inside wall, which results in cracking failure caused by stress concentration near the inside wall position. The ring -shape crack can be eliminated by increasing the cooling rate of the inside wall of the steel pipe during quenching, improving the uniformity of the cooling rate between the inside and outside wall, and controlling the temperature after quenching to be within 150 ~200 ℃ to reduce the quenching stress by self-tempering.

SAE 4140 is a CrMo low alloy structural steel, is the American ASTM A519 standard grade, in the national standard 42CrMo based on the increase in the Mn content; therefore, SAE 4140 hardenability has been further improved. SAE 4140 seamless steel pipe, instead of solid forgings, rolling billet production of various types of hollow shafts, cylinders, sleeves, and other parts can significantly improve production efficiency and save steel; SAE 4140 steel pipe is widely used in oil and gas field mining screw drilling tools and other drilling equipment. SAE 4140 seamless steel pipe tempering treatment can meet the requirements of different steel strengths and toughness matching by optimizing the heat treatment process. Still, it is often found to affect product delivery defects in the production process. This paper mainly focuses on SAE 4140 steel pipe in the quenching process in the middle of the wall thickness of the end of the pipe, produces a ring-shaped crack defect analysis, and puts forward improvement measures.

1. Test Materials and Methods

A company produced specifications for ∅ 139.7 × 31.75 mm SAE 4140 steel grade seamless steel pipe, the production process for the billet heating → piercing → rolling → sizing → tempering (850 ℃ soaking time of 70 min quenching + pipe rotating outside the water shower cooling +735 ℃ soaking time of 2 h tempering) → Flaw Detection and Inspection. After the tempering treatment, the flaw detection inspection revealed that there was an annular crack in the middle of the wall thickness at the pipe end, as shown in Fig. 1; the annular crack appeared at about 21~24 mm away from the exterior, circled the circumference of the pipe, and was partially discontinuous, while no such defect was found in the pipe body.

Fig.1 The Ring-shaped Crack at Pipe End

Take the batch of steel pipe quenching samples for quenching analysis and quenching organization observation, and spectral analysis of the composition of the steel pipe, at the same time, in the tempered steel pipe cracks to take high power samples to observe the crack micro-morphology, grain size level, and in the scanning electron microscope with a spectrometer for the cracks in the internal composition of the micro-area analysis.

2. Test Results

2.1 Chemical composition

Table 1 shows the chemical composition spectral analysis results, and the composition of the elements is in accordance with the requirements of the ASTM A519 standard.

Table 1 Chemical composition analysis results (mass fraction, %)

Element	C	Si	Mn	P	S	Cr	Mo	Cu	Ni
Content	0.39	0.20	0.82	0.01	0.005	0.94	0.18	0.05	0.02
ASTM A519 Requirement	0.38-0.43	0.15-0.35	0.75-1.00	≤ 0.04	≤ 0.04	0.8-1.1	0.15-0.25	≤ 0.35	≤ 0.25

2.2 Tube Hardenability Test

On the quenched samples of the total wall thickness quenching hardness test, the total wall thickness hardness results, as shown in Figure 2, can be seen in Figure 2, in 21 ~ 24 mm from the outside of the quenching hardness began to drop significantly, and from the outside of the 21 ~ 24 mm is the high-temperature tempering of the pipe found in the region of the ring crack, the area below and above the wall thickness of the hardness of the extreme difference between the position of the wall thickness of the region reached 5 ( HRC) or so. The hardness difference between this area’s lower and upper wall thicknesses is about 5 (HRC). The metallographic organization in the quenched state is shown in Fig. 3. From the metallographic organization in Fig. 3; it can be seen that the organization in the outer region of the pipe is a small amount of ferrite + martensite, while the organization near the inner surface is not quenched, with a small amount of ferrite and bainite, which leads to the low quenching hardness from the outer surface of the pipe to the inner surface of the pipe at a distance of 21 mm. The high degree of consistency of ring cracks in the pipe wall and the position of extreme difference in quenching hardness suggest that ring cracks are likely to be produced in the quenching process. The high consistency between the ring cracks’ location and the inferior quench hardness indicates that the ring cracks may have been produced during the quenching process.

Fig.2 The Quenching Hardness Value in Full Wall Thickness

Fig.3 Quenching Structure of Steel Pipe

2.3 The metallographic results of the steel pipe are shown in Fig. 4 and Fig. 5, respectively.

The matrix organization of the steel pipe is tempered austenite + a small amount of ferrite + a small amount of bainite, with a grain size of 8, which is an average tempered organization; the cracks extend along the longitudinal direction, which belongs along the crystalline cracking, and the two sides of the cracks have the typical characteristics of engaging; there is the phenomenon of decarburization on both sides, and high-temperature grey oxide layer is observable on the surface of the cracks. There is decarburization on both sides, and a high-temperature gray oxide layer can be observed on the crack surface, and no non-metallic inclusions can be seen in the vicinity of the crack.

Fig.4 Observations of Crack Morphology

Fig.5 Microstructure of Crack

2.4 Crack fracture morphology and energy spectrum analysis results

After the fracture is opened, the micro-morphology of the fracture is observed under the scanning electron microscope, as shown in Fig. 6, which shows that the fracture has been subjected to high temperatures and high-temperature oxidation has occurred on the surface. The fracture is mainly along the crystal fracture, with the grain size ranging from 20 to 30 μm, and no coarse grains and abnormal organizational defects are found; the energy spectrum analysis shows that the surface of the fracture is mainly composed of iron and its oxides, and no abnormal foreign elements are seen. Spectral analysis shows that the fracture surface is primarily iron and its oxides, with no abnormal foreign element.

Fig.6 Fracture Morphology of Crack

3 Analysis and Discussion

3.1 Analysis of crack defects

From the viewpoint of crack micro-morphology, the crack opening is straight; the tail is curved and sharp; the crack extension path shows the characteristics of cracking along the crystal, and the two sides of the crack have typical meshing characteristics, which are the usual characteristics of quenching cracks. Still, the metallographic examination found that there are decarburization phenomena on both sides of the crack, which is not in line with the characteristics of the traditional quenching cracks, taking into account the fact that the tempering temperature of the steel pipe is 735 ℃, and Ac1 is 738 ℃ in SAE 4140, which is not in line with the conventional characteristics of quenching cracks. Considering that the tempering temperature used for the pipe is 735 °C and the Ac1 of SAE 4140 is 738 °C, which are very close to each other, it is assumed that the decarburization on both sides of the crack is related to the high-temperature tempering during the tempering (735 °C) and is not a crack that already existed before the heat treatment of the pipe.

3.2 Cracking causes

The causes of quenching cracks are generally related to the quenching heating temperature, quenching cooling rate, metallurgical defects, and quenching stresses. From the results of compositional analysis, the chemical composition of the pipe meets the requirements of SAE 4140 steel grade in ASTM A519 standard, and no exceeding elements were found; no non-metallic inclusions were found near the cracks, and the energy spectrum analysis at the crack fracture showed that the gray oxidation products in the cracks were Fe and its oxides, and no abnormal foreign elements were seen, so it can be ruled out that metallurgical defects caused the annular cracks; the grain size grade of the pipe was Grade 8, and the grain size grade was Grade 7, and the grain size was Grade 8, and the grain size was Grade 8. The grain size level of the pipe is 8; the grain is refined and not coarse, which indicates that the quenching crack has nothing to do with the quenching heating temperature.

The formation of quench cracks is closely related to the quenching stresses, divided into thermal and organizational stresses. Thermal stress is due to the cooling process of the steel pipe; the surface layer and the heart of the steel pipe cooling rate are not consistent, resulting in uneven contraction of the material and internal stresses; the result is the surface layer of the steel pipe is subjected to compressive stresses and the heart of the tensile stresses; tissue stresses is the quenching of the steel pipe organization to the martensite transformation, along with the expansion of the volume of inconsistency in the generation of the internal stresses, the organization of stresses generated by the result is the surface layer of tensile stresses, the center of the tensile stresses. These two kinds of stresses in the steel pipe exist in the same part, but the direction role is the opposite; the combined effect of the result is that one of the two stresses’ dominant factor, thermal stress dominant role is the result of the workpiece heart tensile, surface pressure; tissue stress dominant role is the result of the workpiece heart tensile pressure surface tensile.

SAE 4140 steel pipe quenching using rotating outer shower cooling production, the cooling rate of the outer surface is much greater than the inner surface, the outer metal of the steel pipe all quenched, while the inner metal is not entirely quenched to produce part of the ferrite and bainite organization, the inner metal due to the inner metal can not be fully converted into martensitic organization, the inner metal of the steel pipe is inevitably subjected to the tensile stress generated by the expansion of the outer wall of the martensite, and at the same time, due to the different types of organization, its specific volume is different between the inner and outer metal At the same time, due to the various kinds of organization, the particular volume of the inner and outer layers of the metal is different, and the shrinkage rate is not the same during cooling, tensile stress will also be generated at the interface of the two types of organization, and the distribution of the stress is dominated by the thermal stresses, and the tensile stress generated at the interface of the two types of organization inside the pipe is the largest, resulting in the ring quenching cracks occurring in the area of the wall thickness of the pipe close to the inner surface (21~24 mm away from the outer surface); in addition, the end of the steel pipe is a geometry-sensitive part of the whole pipe, prone to generate stress. In addition, the end of the pipe is a geometrically sensitive part of the entire pipe, which is prone to stress concentration. This ring crack usually occurs only at the end of the pipe, and such cracks have not been found in the pipe body.

In summary, quenched SAE 4140 thick-walled steel pipe ring-shaped cracks are caused by uneven cooling of the inner and outer walls; the cooling rate of the outer wall is much higher than that of the inner wall; production of SAE 4140 thick-walled steel pipe to change the existing cooling method, can not be used only outside the cooling process, the need to strengthen the cooling of the inner wall of the steel pipe, to improve the uniformity of the cooling rate of the inner and outer walls of the thick-walled steel pipe to reduce the stress concentration, eliminating the ring cracks. Ring cracks.

3.3 Improvement measures

To avoid quenching cracks, in the quenching process design, all the conditions that contribute to the development of quenching tensile stresses are factors for the formation of cracks, including the heating temperature, cooling process, and discharge temperature. Improved process measures proposed include: quenching temperature of 830-850 ℃; the use of an internal nozzle matched with the centerline of the pipe, control of the appropriate internal spray flow, improving the cooling rate of the inner hole to ensure that the cooling rate of the inner and outer walls of thick-walled steel pipe cooling rate uniformity; control of the post-quenching temperature of 150-200 ℃, the use of steel pipe residual temperature of the self-tempering, reduce the quenching stresses in the steel pipe.

The use of improved technology produces ∅158.75 × 34.93 mm, ∅139.7 × 31.75 mm, ∅254 × 38.1 mm, ∅224 × 26 mm, and so on, according to dozens of steel pipe specifications. After ultrasonic flaw inspection, the products are qualified, with no ring-quenching cracks.

4. Conclusion

(1) According to the macroscopic and microscopic characteristics of pipe cracks, the annular cracks at the pipe ends of SAE 4140 steel pipes belong to the cracking failure caused by quenching stress, which usually occurs at the pipe ends.

(2) Quenched SAE 4140 thick-walled steel pipe ring-shaped cracks are caused by uneven cooling of the inner and outer walls. The cooling rate of the outer wall is much higher than the inner wall’s. To improve the uniformity of the cooling rate of the inner and outer walls of the thick-walled steel pipe, the production of SAE 4140 thick-walled steel pipe needs to strengthen the cooling of the inner wall.

ASME SA213 T91: How Much Do You Know?

October 16, 2024/in Industry Knowledge/by Energy Steel

Background & Introduction

ASME SA213 T91, the steel number in the ASME SA213/SA213M standard, belongs to the improved 9Cr-1Mo steel, which was developed from the 1970s to the 1980s by the U.S. Rubber Ridge National Laboratory and the Metallurgical Materials Laboratory of the U.S. Combustion Engineering Corporation in cooperation. Developed based on the earlier 9Cr-1Mo steel, used in nuclear power (can also be used in other areas) high-temperature pressurized parts materials, is the third generation of hot-strength steel products; its main feature is to reduce the carbon content, in the limitation of the upper and lower limits of the carbon content, and more stringent control of the content of residual elements, such as P and S, at the same time, adding a trace of 0.030-0.070% of the N, and traces of the solid carbide-forming elements 0.18-0.25% of V and 0.06-0.10% of Nb, to refine the grain requirements, thereby improving the plastic toughness and weldability of steel, improve the stability of steel at high temperatures, after this multi-composite reinforcement, the formation of a new type of martensitic high-chromium heat-resistant alloy steel.

ASME SA213 T91, usually producing products for small-diameter tubes, is mainly used in boilers, superheaters, and heat exchangers.

International Corresponding Grades of T91 Steel

Country	USA	Germany	Japan	France	China
Equivalent Steel Grade	SA-213 T91	X10CrMoVNNb91	HCM95	TUZ10CDVNb0901	10Cr9Mo1VNbN

We will recognize this steel from several aspects here.

I. Chemical Composition of ASME SA213 T91

Element

Content

0.07-0.14

0.30-0.60

≤0.020

≤0.010

0.20-0.50

8.00-9.50

0.85-1.05

≤0.40

0.18-0.25

0.06-0.10

0.030-0.070

≤0.020

II. Performance Analysis

2.1 The role of alloying elements on the material properties: T91 steel alloying elements play a solid solution strengthening and diffusion strengthening role and improve the steel’s oxidation and corrosion resistance, analyzed explicitly as follows.
2.1.1 Carbon is the most apparent solid solution strengthening effect of steel elements; with the increase in carbon content, the short-term strength of steel, plasticity, and toughness decline, the T91 such steel, the rise in carbon content will accelerate the speed of carbide spheroidization and aggregation speed, accelerate the redistribution of alloying elements, reducing the weldability, corrosion resistance and oxidation resistance of steel, so heat-resistant steel generally want to reduce the amount of carbon content. Still, the strength of steel will be decreased if the carbon content is too low. T91 steel, compared with 12Cr1MoV steel, has a reduced carbon content of 20%, which is a careful consideration of the impact of the above factors.
2.1.2 T91 steel contains traces of nitrogen; the role of nitrogen is reflected in two aspects. On the one hand, the role of solid solution strengthening, nitrogen at room temperature in the steel solubility is minimal, T91 steel welded heat-affected zone in the process of welding heating and post-weld heat treatment, there will be a succession of solid solution and precipitation process of V.N.: Welding heating heat-affected zone has been formed within the austenitic organization due to the solubility of the V.N., nitrogen content increases, and after that, the degree of supersaturation in the organization of the room temperature increases in the subsequent heat treatment of the weld there is slight V.N. precipitation, which increases the stability of the organization and improves the value of the lasting strength of the heat affected zone. On the other hand, T91 steel also contains a small amount of A1; nitrogen can be formed with its A1N, A1N in more than 1 100 ℃ only a large number of dissolved into the matrix, and then re-precipitated at lower temperatures, which can play a better diffusion strengthening effect.
2.1.3 add chromium mainly to improve the oxidation resistance of heat-resistant steel, corrosion resistance, chromium content of less than 5%, 600 ℃ began to oxidize violently, while the amount of chromium content up to 5% has an excellent oxidation resistance. 12Cr1MoV steel in the following 580 ℃ has a good oxidation resistance, the depth of corrosion of 0.05 mm/a, 600 ℃ when the performance began to deteriorate, the depth of corrosion of 0.13 mm / a. T91 containing chromium content of 1 100 ℃ before a large number of dissolved into the matrix, and at lower temperatures and re-precipitation can play a sound diffusion strengthening effect. /T91 chromium content increased to about 9%, the use of temperature can reach 650 ℃, the primary measure is to make the matrix dissolved in more chromium.
2.1.4 vanadium and niobium are vital carbide-forming elements. When added to form a fine and stable alloy carbide with Carbon, there is a solid diffusion-strengthening effect.
2.1.5 Adding molybdenum mainly improves the thermal strength of the steel and strengthens solid solutions.

2.2 Mechanical Properties

T91 billet, after the final heat treatment for normalizing + high-temperature tempering, has a room temperature tensile strength ≥ 585 MPa, room temperature yield strength ≥ 415 MPa, hardness ≤ 250 HB, elongation (50 mm spacing of the standard circular specimen) ≥ 20%, the permissible stress value [σ] 650 ℃ = 30 MPa.

Heat treatment process: normalizing temperature of 1040 ℃, holding time of not less than 10 min, tempering temperature of 730 ~ 780 ℃, holding time of not less than one h.

2.3 Welding performance

In accordance with the International Welding Institute’s recommended Carbon equivalent formula, T91 steel carbon equivalent is calculated at 2.43%, and visible T91 weldability is poor.
The steel does not tend to reheat Cracking.

2.3.1 Problems with T91 welding

2.3.1.1 Cracking of hardened organization in the heat-affected zone
T91 cooling critical speed is low, austenite is very stable, and cooling does not quickly occur during standard pearlite transformation. It must be cooled to a lower temperature (about 400 ℃) to be transformed into martensite and coarse organization.
Welding produced by the heat-affected zone of the various organizations has different densities, coefficients of expansion, and different lattice forms in the heating and cooling process will inevitably be accompanied by different volume expansion and contraction; on the other hand, due to the welding heating has uneven and high-temperature characteristics, so the T91 welded joints are enormous internal stresses. Hardened coarse martensite organization joints that are in a complex stress state, at the same time, the weld cooling process hydrogen diffusion from the weld to the near-seam area, the presence of hydrogen has contributed to the martensite embrittlement, this combination of effects, it is easy to produce cold cracks in the quenched area.

2.3.1.2 Heat-affected zone grain growth
Welding thermal cycling significantly affects grain growth in the heat-affected zone of welded joints, especially in the fusion zone immediately adjacent to the maximum heating temperature. When the cooling rate is minor, the welded heat-affected zone will appear coarse massive ferrite and carbide organization so that the plasticity of the steel decreases significantly; the cooling rate is significant due to the production of coarse martensite organization, but also the plasticity of welded joints will be reduced.

2.3.1.3 Generation of softened layer
T91 steel welded in the tempered state, the heat-affected zone produces an inevitable softening layer, which is more severe than the softening of pearlite heat-resistant steel. Softening is more remarkable when using specifications with slower heating and cooling rates. In addition, the width of the softened layer and its distance from the fusion line are related to the heating conditions and characteristics of welding, preheating, and post-weld heat treatment.

2.3.1.4 Stress corrosion cracking
T91 steel in the post-weld heat treatment before the cooling temperature is generally not less than 100 ℃. If the cooling is at room temperature and the environment is relatively humid, it is easy to stress corrosion cracking. German regulations: Before the post-weld heat treatment, it must be cooled to below 150 ℃. In the case of thicker workpieces, fillet welds, and poor geometry, the cooling temperature is not less than 100 ℃. If cooling at room temperature and humidity is strictly prohibited, otherwise it is easy to produce stress corrosion cracks.

2.3.2 Welding process

2.3.2.1 Welding method: Manual welding, tungsten-pole gas-shielded, or melting-pole automatic welding can be used.
2.3.2.2 Welding material: can choose WE690 welding wire or welding rod.

Welding material selection:
(1) Welding of the same kind of steel – if manual welding can be used to make CM-9Cb manual welding rod, tungsten gas shielded welding can be used to make TGS-9Cb, melting pole automatic welding can be used to make MGS-9Cb wire;
(2) dissimilar steel welding – such as welding with austenitic stainless steel available ERNiCr-3 welding consumables.

2.3.2.3 Welding process points:
(1) the choice of preheating temperature before welding
T91 steel Ms point is about 400 ℃; preheating temperature is generally selected at 200 ~ 250 ℃. The preheating temperature can not be too high. Otherwise, the joint cooling rate is reduced, which may be caused in the welded joints at the grain boundaries of carbide precipitation and the formation of ferrite organization, thus significantly reducing the impact toughness of the steel welded joints at room temperature. Germany provides a preheating temperature of 180 ~ 250 ℃; the U.S. C.E. provides a preheating temperature of 120 ~ 205 ℃.

(2) the choice of welding channel / interlayer temperature
Interlayer temperature shall not be lower than the lower limit of the preheating temperature. Still, as with the selection of preheating temperature, the interlayer temperature can not be too high.T91 welding interlayer temperature is generally controlled at 200 ~ 300 ℃. French regulations: the interlayer temperature does not exceed 300 ℃. U.S. regulations: interlayer temperature can be located between 170 ~ 230 ℃.

(3) the choice of post-weld heat treatment starting temperature
T91 requires post-weld cooling to below the Ms point and hold for a certain period before tempering treatment, with a post-weld cooling rate of 80 ~ 100 ℃ / h. If not insulated, the joint austenitic organization may not be fully transformed; tempering heating will promote carbide precipitation along the austenitic grain boundaries, making the organization very brittle. However, T91 cannot be cooled to room temperature before tempering after welding because cold Cracking is dangerous when its welded joints are cooled to room temperature. For T91, the best post-weld heat treatment starting temperature of 100 ~ 150 ℃ and holding for one hour can ensure complete organization transformation.

(4) post-weld heat treatment tempering temperature, holding time, tempering cooling rate selection
Tempering temperature: T91 steel cold cracking tendency is more significant, and under certain conditions, it is prone to delayed Cracking, so the welded joints must be tempered within 24 hours after welding. T91 post-weld state of the organization of the lath martensite, after tempering, can be changed to tempered martensite; its performance is superior to the lath martensite. The tempering temperature is low; the tempering effect is not apparent; the weld metal is easy to age and embrittlement; the tempering temperature is too high (more than the AC1 line), the joint may be austenitized again, and in the subsequent cooling process to re-quench. At the same time, as described earlier in this paper, determining the tempering temperature should also consider the influence of the joint softening layer. In general, T91 tempering temperature of 730 ~ 780 ℃.
Holding time: T91 requires a post-weld tempering holding time of at least one hour to ensure its organization is wholly transformed into tempered martensite.
Tempering cooling rate: To reduce the residual stress of T91 steel welded joints, the cooling rate must be less than five ℃ / min.
Overall, the T91 steel welding process in the temperature control process can be briefly expressed in the figure below:

Temperature control process in the welding process of T91 steel tube

III. Understanding of ASME SA213 T91

3.1 T91 steel, by the principle of alloying, especially adding a small amount of niobium, vanadium, and other trace elements, significantly improves high-temperature strength and oxidation resistance compared to 12 Cr1MoV steel, but its welding performance is poor.
3.2 T91 steel has a greater tendency to cold Cracking during welding and needs to be pre-welding preheated to 200 ~ 250 ℃, maintaining the interlayer temperature at 200 ~ 300 ℃, which can effectively prevent cold cracks.
3.3 T91 steel post-welding heat treatment must be cooled to 100 ~ 150 ℃, insulation one hour, warming and tempering temperature to 730 ~ 780 ℃, insulation time of not less than one h, and finally, not more than 5 ℃ / min speed cooling to room temperature.

IV. Manufacturing Process of ASME SA213 T91

The manufacturing process of SA213 T91 requires several methods, including smelting, piercing, and rolling. The smelting process must control the chemical composition to ensure the steel pipe has excellent corrosion resistance. The piercing and rolling processes require precise temperature and pressure control to obtain the required mechanical properties and dimensional accuracy. In addition, steel pipes need to be heat-treated to remove internal stresses and improve corrosion resistance.

V. Applications of ASME SA213 T91

ASME SA213 T91 is a high-chromium heat-resistant steel, mainly used in the manufacture of high-temperature superheaters and reheaters and other pressurized parts of subcritical and supercritical power station boilers with metal wall temperatures not exceeding 625°C, and can also be used as high-temperature pressurized parts of pressure vessels and nuclear power. SA213 T91 has excellent creep resistance and can maintain stable size and shape at high temperatures and under long-term loads. Its main applications include boilers, superheaters, heat exchangers, and other equipment in the power, chemical, and petroleum industries. It is widely used in the petrochemical industry’s water-cooled walls of high-pressure boilers, economizer tubes, superheaters, reheaters, and tubes.

NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1

October 14, 2024/in Industry Knowledge/by Energy Steel

Introduction

In the oil and gas industry, particularly in onshore and offshore environments, ensuring the longevity and reliability of materials exposed to aggressive conditions is paramount. This is where standards like NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1 come into play. Both standards provide critical guidance for material selection in sour service environments. However, understanding the differences between them is essential for selecting the right materials for your operations.

In this blog post, we will explore the key differences between NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1, and offer practical advice for oil and gas professionals navigating these standards. We will also discuss the specific applications, challenges, and solutions these standards provide, especially in the context of harsh oil and gas field environments.

What Are NACE MR0175/ISO 15156 and NACE MR0103/ISO 17495-1?

NACE MR0175/ISO 15156:
This standard is globally recognized for governing material selection and corrosion control in sour gas environments, where hydrogen sulfide (H₂S) is present. It provides guidelines for the design, manufacturing, and maintenance of materials used in onshore and offshore oil and gas operations. The goal is to mitigate the risks associated with hydrogen-induced cracking (HIC), sulfide stress cracking (SSC), and stress corrosion cracking (SCC), which can compromise the integrity of critical equipment like pipelines, valves, and wellheads.

NACE MR0103/ISO 17495-1:
On the other hand, NACE MR0103/ISO 17495-1 is primarily focused on materials used in refining and chemical processing environments, where exposure to sour service may occur, but with a slightly different scope. It covers the requirements for equipment exposed to mildly corrosive conditions, with an emphasis on ensuring materials can withstand the aggressive nature of specific refining processes like distillation or cracking, where the corrosion risk is comparatively lower than in upstream oil and gas operations.

NACE MR0175 ISO 15156 vs NACE MR0103 ISO 17495-1

Main Differences: NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1

Now that we have an overview of each standard, it is important to highlight the differences that may impact material selection in the field. These distinctions can significantly affect the performance of materials and the safety of operations.

1. Scope of Application

The primary difference between NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1 lies in the scope of their application.

NACE MR0175/ISO 15156 is tailored for equipment used in sour service environments where hydrogen sulfide is present. It is crucial in upstream activities such as exploration, production, and transportation of oil and gas, especially in offshore and onshore fields that deal with sour gas (gas containing hydrogen sulfide).

NACE MR0103/ISO 17495-1, while still addressing sour service, is more focused on refining and chemical industries, particularly where sour gas is involved in processes like refining, distillation, and cracking.

2. Environmental Severity

The environmental conditions are also a key factor in the application of these standards. NACE MR0175/ISO 15156 addresses more severe conditions of sour service. For instance, it covers higher concentrations of hydrogen sulfide, which is more corrosive and presents a higher risk for material degradation through mechanisms such as hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC).

In contrast, NACE MR0103/ISO 17495-1 considers environments that may be less severe in terms of hydrogen sulfide exposure, though still critical in refinery and chemical plant environments. The chemical composition of the fluids involved in the refining processes may not be as aggressive as those encountered in sour gas fields but still presents risks for corrosion.

3. Material Requirements

Both standards provide specific criteria for material selection, but they differ in their stringent requirements. NACE MR0175/ISO 15156 places greater emphasis on preventing hydrogen-related corrosion in materials, which can occur even in very low concentrations of hydrogen sulfide. This standard calls for materials that are resistant to SSC, HIC, and corrosion fatigue in sour environments.

On the other hand, NACE MR0103/ISO 17495-1 is less prescriptive in terms of hydrogen-related cracking but requires materials that can handle corrosive agents in refining processes, often focusing more on general corrosion resistance rather than specific hydrogen-related risks.

4. Testing and Verification

Both standards require testing and verification to ensure materials will perform in their respective environments. However, NACE MR0175/ISO 15156 demands more extensive testing and more detailed verification of material performance under sour service conditions. The tests include specific guidelines for SSC, HIC, and other failure modes associated with sour gas environments.

NACE MR0103/ISO 17495-1, while also requiring material testing, is often more flexible in terms of the testing criteria, focusing on ensuring that materials meet general corrosion resistance standards rather than focusing specifically on hydrogen sulfide-related risks.

Why Should You Care About NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1?

Understanding these differences can help prevent material failures, ensure operational safety, and comply with industry regulations. Whether you are working on an offshore oil rig, a pipeline project, or in a refinery, using the appropriate materials per these standards will safeguard against costly failures, unexpected downtime, and potential environmental hazards.

For oil and gas operations, especially in onshore and offshore sour service environments, NACE MR0175/ISO 15156 is the go-to standard. It ensures that materials withstand the harshest environments, mitigating risks like SSC and HIC that can lead to catastrophic failures.

In contrast, for operations in refining or chemical processing, NACE MR0103/ISO 17495-1 offers more tailored guidance. It allows materials to be used effectively in environments with sour gas but with less aggressive conditions compared to oil and gas extraction. The focus here is more on general corrosion resistance in processing environments.

Practical Guidance for Oil and Gas Professionals

When selecting materials for projects in either category, consider the following:

Understand Your Environment: Evaluate whether your operation is involved in sour gas extraction (upstream) or refining and chemical processing (downstream). This will help you determine which standard to apply.

Material Selection: Choose materials that are compliant with the relevant standard based on environmental conditions and the type of service (sour gas vs. refining). Stainless steels, high-alloy materials, and corrosion-resistant alloys are often recommended based on the severity of the environment.

Testing and Verification: Ensure that all materials are tested according to the respective standards. For sour gas environments, additional testing for SSC, HIC, and corrosion fatigue may be necessary.

Consult with Experts: It is always a good idea to consult with corrosion specialists or material engineers familiar with NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1 to ensure optimal material performance.

Conclusion

In conclusion, understanding the distinction between NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1 is essential for making informed decisions on material selection for both upstream and downstream oil and gas applications. By choosing the appropriate standard for your operation, you ensure the long-term integrity of your equipment and help prevent catastrophic failures that can arise from improperly specified materials. Whether you are working with sour gas in offshore fields or chemical processing in refineries, these standards will provide the necessary guidelines to protect your assets and maintain safety.

If you are unsure which standard to follow or need further assistance with material selection, reach out to a materials expert for tailored advice on NACE MR0175/ISO 15156 vs NACE MR0103/ISO 17495-1 and ensure your projects are both safe and compliant with industry best practices.

Boiler and Heat Exchanger: Seamless Tubes Selection Guide

October 13, 2024/in Industry Knowledge/by Energy Steel

Introduction

In industries such as power generation, oil and gas, petrochemicals, and refineries, seamless tubes are essential components, especially in equipment that must withstand extreme temperatures, high pressures, and harsh, corrosive environments. Boilers, heat exchangers, condensers, superheaters, air preheaters, and economizers use these tubes. Each of these applications demands specific material properties to ensure performance, safety, and longevity. The selection of seamless tubes for the boiler and heat exchanger depends on the specific temperature, pressure, corrosion resistance, and mechanical strength.

This guide provides an in-depth look into the various materials used for seamless tubes, including carbon steel, alloy steel, stainless steel, titanium alloys, nickel-based alloys, copper alloys, and zirconium alloys. We will also explore the relevant standards and grades, thereby helping you make more informed decisions for your Boiler and Heat Exchanger projects.

Overview of CS, AS, SS, Nickel Alloys, Titanium and Zirconium Alloys, Copper & Copper Alloys

1. Corrosion Resistance Properties

Each material used for seamless tubes has specific corrosion resistance properties that determine its suitability for different environments.

Carbon Steel: Limited corrosion resistance, typically used with protective coatings or linings. Subject to rusting in the presence of water and oxygen unless treated.
Alloy Steel: Moderate resistance to oxidation and corrosion. Alloy additions like chromium and molybdenum improve corrosion resistance at high temperatures.
Stainless Steel: Excellent resistance to general corrosion, stress corrosion cracking, and pitting due to its chromium content. Higher grades, such as 316L, have improved resistance to chloride-induced corrosion.
Nickel-Based Alloys: Outstanding resistance to aggressive environments like acidic, alkaline, and chloride-rich environments. Highly corrosive applications use alloys like Inconel 625, Hastelloy C276, and Alloy 825.
Titanium and Zirconium: Superior resistance to seawater brines, and other highly corrosive media. Titanium is especially resistant to chloride and acidic environments, while zirconium alloys excel in highly acidic conditions.
Copper and Copper Alloys: Excellent resistance to corrosion in freshwater and seawater, with copper-nickel alloys showing exceptional resistance in marine environments.

2. Physical and Thermal Properties

Carbon Steel:
Density: 7.85 g/cm³
Melting Point: 1,425-1,500°C
Thermal Conductivity: ~50 W/m·K
Alloy Steel:
Density: Varies slightly by alloying elements, typically around 7.85 g/cm³
Melting Point: 1,450-1,530°C
Thermal Conductivity: Lower than carbon steel due to alloying elements.
Stainless Steel:
Density: 7.75-8.0 g/cm³
Melting Point: ~1,400-1,530°C
Thermal Conductivity: ~16 W/m·K (lower than carbon steel).
Nickel-Based Alloys:
Density: 8.4-8.9 g/cm³ (depends on alloy)
Melting Point: 1,300-1,400°C
Thermal Conductivity: Typically low, ~10-16 W/m·K.
Titanium:
Density: 4.51 g/cm³
Melting Point: 1,668°C
Thermal Conductivity: ~22 W/m·K (relatively low).
Copper:
Density: 8.94 g/cm³
Melting Point: 1,084°C
Thermal Conductivity: ~390 W/m·K (excellent thermal conductivity).

3. Chemical Composition

Carbon Steel: Primarily iron with 0.3%-1.2% carbon and small amounts of manganese, silicon, and sulfur.
Alloy Steel: Includes elements like chromium, molybdenum, vanadium, and tungsten to improve strength and temperature resistance.
Stainless Steel: Typically contains 10.5%-30% chromium, along with nickel, molybdenum, and other elements depending on the grade.
Nickel-Based Alloys: Predominantly nickel (40%-70%) with chromium, molybdenum, and other alloying elements to enhance corrosion resistance.
Titanium: Grade 1 and 2 are commercially pure titanium, while Grade 5 (Ti-6Al-4V) includes 6% aluminum and 4% vanadium.
Copper Alloys: Copper alloys contain various elements like nickel (10%-30%) for corrosion resistance (e.g., Cu-Ni 90/10).

4. Mechanical Properties

Carbon Steel: Tensile Strength: 400-500 MPa, Yield Strength: 250-350 MPa, Elongation: 15%-25%
Alloy Steel: Tensile Strength: 500-900 MPa, Yield Strength: 300-700 MPa, Elongation: 10%-25%
Stainless Steel: Tensile Strength: 485-690 MPa (304/316), Yield Strength: 170-300 MPa, Elongation: 35%-40%
Nickel-Based Alloys: Tensile Strength: 550-1,000 MPa (Inconel 625), Yield Strength: 300-600 MPa, Elongation: 25%-50%
Titanium: Tensile Strength: 240-900 MPa (varies by grade), Yield Strength: 170-880 MPa, Elongation: 15%-30%
Copper Alloys: Tensile Strength: 200-500 MPa (depends on the alloy), Yield Strength: 100-300 MPa, Elongation: 20%-35%

5. Heat Treatment (Delivery Condition)

Carbon and Alloy Steel: Delivered in annealed or normalized condition. Heat treatments include quenching and tempering to improve strength and toughness.
Stainless Steel: Delivered in an annealed condition to remove internal stresses and improve ductility.
Nickel-Based Alloys: Solution annealed to optimize mechanical properties and corrosion resistance.
Titanium and Zirconium: Typically delivered in an annealed condition to maximize ductility and toughness.
Copper Alloys: Delivered in soft annealed condition, especially for forming applications.

6. Forming

Carbon and Alloy Steel: Can be hot or cold-formed, but alloy steels require more effort due to their higher strength.
Stainless Steel: Cold forming is common, though work-hardening rates are higher than carbon steel.
Nickel-Based Alloys: More challenging to form due to high strength and work-hardening rates; often requires hot working.
Titanium: Forming is best done at elevated temperatures due to its high strength at room temperature.
Copper Alloys: Easy to form due to good ductility.

7. Welding

Carbon and Alloy Steel: Generally easy to weld using conventional techniques, but preheat and post-weld heat treatment (PWHT) may be required.
Stainless Steel: Common welding methods include TIG, MIG, and arc welding. Careful control of heat input is necessary to avoid sensitization.
Nickel-Based Alloys: Challenging to weld due to high thermal expansion and susceptibility to cracking.
Titanium: Welded in a shielded environment (inert gas) to avoid contamination. Precautions are needed due to titanium’s reactivity at high temperatures.
Copper Alloys: Easy to weld, especially copper-nickel alloys, but preheating may be required to prevent cracking.

8. Corrosion of Welds

Stainless Steel: Can suffer from localized corrosion (e.g., pitting, crevice corrosion) at the weld heat-affected zone if not properly controlled.
Nickel-Based Alloys: Susceptible to stress corrosion cracking if exposed to chlorides at high temperatures.
Titanium: Welds must be properly shielded from oxygen to avoid embrittlement.

9. Descaling, Pickling, and Cleaning

Carbon and Alloy Steel: Pickling removes surface oxides after heat treatment. Common acids include hydrochloric and sulfuric acids.
Stainless Steel and Nickel Alloys: Pickling with nitric/hydrofluoric acid is used to remove heat tint and restore corrosion resistance after welding.
Titanium: Mild acid pickling solutions are used to clean the surface and remove oxides without damaging the metal.
Copper Alloys: Acid cleaning is used to remove surface tarnishes and oxides.

10. Surface Process (AP, BA, MP, EP, etc.)

AP (Annealed & Pickled): Standard finish for most stainless and nickel alloys after annealing and pickling.
BA (Bright Annealed): Achieved by annealing in a controlled atmosphere to produce a smooth, reflective surface.
MP (Mechanically Polished): Mechanical polishing improves surface smoothness, reducing the risk of contamination and corrosion initiation.
EP (Electropolished): An electrochemical process that removes surface material to create an ultra-smooth finish, reducing the surface roughness and improving corrosion resistance.

Stainless Heat Exchanger

I. Understanding Seamless Tubes

Seamless tubes differ from welded tubes in that they do not have a welded seam, which can be a weak point in some high-pressure applications. Seamless tubes are initially formed from a solid billet, which is then heated, and subsequently, it is either extruded or drawn over a mandrel to create the tube shape. The absence of seams gives them superior strength and reliability, making them ideal for high-pressure and high-temperature environments.

Common Applications:

Boilers: Seamless tubes are essential in the construction of water-tube and fire-tube boilers, where high temperatures and pressures are present.
Heat Exchangers: Used to transfer heat between two fluids, seamless tubes in heat exchangers must resist corrosion and maintain thermal efficiency.
Condensers: Seamless tubes help condense steam into water in power generation and refrigeration systems.
Superheaters: Seamless tubes are used to superheat steam in boilers, enhancing the efficiency of turbines in power plants.
Air Preheaters: These tubes transfer heat from flue gases to air, improving boiler efficiency.
Economizers: Seamless tubes in economizers preheat the feedwater using waste heat from boiler exhaust, boosting thermal efficiency.

Boilers, heat exchangers, condensers, superheaters, air preheaters, and economizers are integral components in several industries, particularly those involved in heat transfer, energy production, and fluid management. Specifically, these components find primary use in the following industries:

1. Power Generation Industry

Boilers: Used in power plants to convert chemical energy into thermal energy, often for steam generation.
Superheaters, Economizers, and Air Preheaters: These components improve efficiency by preheating the combustion air, recovering heat from exhaust gases, and further heating the steam.
Heat Exchangers and Condensers: Used for cooling and heat recovery in thermal power plants, particularly in steam-driven turbines and cooling cycles.

2. Oil & Gas Industry

Heat Exchangers: Crucial in refining processes, where heat is transferred between fluids, such as in crude oil distillation or in offshore platforms for gas processing.
Boilers and Economizers: Found in refineries and petrochemical plants for steam generation and energy recovery.
Condensers: Used to condense gases into liquids during the distillation processes.

3. Chemical Industry

Heat Exchangers: Used extensively to heat or cool chemical reactions, and to recover heat from exothermic reactions.
Boilers and Superheaters: Used to produce the steam required for various chemical processes, and to provide energy for distillation and reaction steps.
Air Preheaters and Economizers: Improve efficiency in energy-intensive chemical processes by recovering heat from exhaust gases and reducing fuel consumption.

4. Marine Industry

Boilers and Heat Exchangers: Essential in marine vessels for steam generation, heating, and cooling systems. Marine heat exchangers are often used to cool the ship’s engines and generate power.
Condensers: Used to convert exhaust steam back into water for reuse in the ship’s boiler systems.

5. Food and Beverage Industry

Heat Exchangers: Commonly used for pasteurization, sterilization, and evaporative processes.
Boilers and Economizers: Used to produce steam for food processing operations and to recover heat from the exhaust to save on fuel consumption.

6. HVAC (Heating, Ventilation, and Air Conditioning)

Heat Exchangers and Air Preheaters: Used in HVAC systems for efficient heat transfer between fluids or gases, providing heating or cooling for buildings and industrial facilities.
Condensers: Used in air conditioning systems to reject heat from the refrigerant.

7. Pulp and Paper Industry

Boilers, Heat Exchangers, and Economizers: Provide steam and heat recovery in processes such as pulping, paper drying, and chemical recovery.
Superheaters and Air Preheaters: Enhance energy efficiency in the recovery boilers and the overall heat balance of paper mills.

8. Metallurgical and Steel Industry

Heat Exchangers: Used for cooling hot gases and liquids in steel production and metallurgical processes.
Boilers and Economizers: Provide heat for various processes like blast furnace operation, heat treatment, and rolling.

9. Pharmaceutical Industry

Heat Exchangers: Used for controlling temperature during drug production, fermentation processes, and sterile environments.
Boilers: Generate the steam required for sterilization and heating of pharmaceutical equipment.

10. Waste-to-Energy Plants

Boilers, Condensers, and Economizers: Used for converting waste into energy through combustion, while recovering heat to improve efficiency.

Now, let’s dive into the materials that make seamless tubes suitable for these demanding applications.

II. Carbon Steel Tubes for Boiler and Heat Exchanger

Carbon steel is one of the most widely used materials for seamless tubes in industrial applications, primarily due to its excellent strength, as well as its affordability and widespread availability. Carbon steel tubes offer moderate temperature and pressure resistance, making them suitable for a wide range of applications.

Properties of Carbon Steel:
High Strength: Carbon steel tubes can withstand significant pressure and stress, making them ideal for use in boilers and heat exchangers.
Cost-Effective: Compared to other materials, carbon steel is relatively inexpensive, which makes it a popular choice in large-scale industrial applications.
Moderate Corrosion Resistance: While carbon steel is not as corrosion-resistant as stainless steel, it can be treated with coatings or linings to improve its longevity in corrosive environments.

Main Standards and Grades:

ASTM A179: This standard covers seamless cold-drawn low-carbon steel tubes used for heat exchanger and condenser applications. These tubes have excellent heat transfer properties and are commonly used in low to moderate-temperature and pressure applications.
ASTM A192: Seamless carbon steel boiler tubes designed for high-pressure service. These tubes are used in steam generation and other high-pressure environments.
ASTM A210: This standard covers seamless medium-carbon steel tubes for boiler and superheater applications. The A-1 and C grades offer varying levels of strength and temperature resistance.
ASTM A334 (Grades 1, 3, 6): Seamless and welded carbon steel tubes designed for low-temperature service. These grades are used in heat exchangers, condensers, and other low-temperature applications.
EN 10216-2 (P235GH, P265GH TC1/TC2): European standard for seamless steel tubes used in pressure applications, particularly in boilers and high-temperature service.

Carbon steel tubes are an excellent choice for Boiler and Heat Exchanger applications where high strength and moderate corrosion resistance are required. However, for applications involving not only extremely high temperatures but also harsh corrosive environments, alloy or stainless steel tubes are often preferred due to their superior resistance and durability.

III. Alloy Steel Tubes for Boiler and Heat Exchanger

Alloy steel tubes are designed for high-temperature and high-pressure Boiler and Heat exchanger applications. These tubes are alloyed with elements like chromium, molybdenum, and vanadium to enhance their strength, hardness, and resistance to corrosion and heat. Alloy steel tubes are widely used in critical applications, such as superheaters, economizers, and high-temperature heat exchangers, due to their exceptional strength and resistance to heat and pressure.

Properties of Alloy Steel:
High Heat Resistance: Alloying elements such as chromium and molybdenum improve the high-temperature performance of these tubes, making them suitable for applications with extreme temperatures.
Improved Corrosion Resistance: Alloy steel tubes offer better resistance to oxidation and corrosion compared to carbon steel, particularly in high-temperature environments.
Enhanced Strength: Alloying elements also increase the strength of these tubes, allowing them to withstand high pressure in boilers and other critical equipment.

Main Standards and Grades:

ASTM A213 (Grades T5, T9, T11, T22, T91, T92): This standard covers seamless ferritic and austenitic alloy-steel tubes for use in boilers, superheaters, and heat exchangers. The grades differ in their alloying composition and are selected based on the specific temperature and pressure requirements.
T5 and T9: Suitable for moderate to high-temperature service.
T11 and T22: Commonly used in high-temperature applications, offering improved heat resistance.
T91 and T92: Advanced high-strength alloys designed for ultra-high-temperature service in power plants.
EN 10216-2 (16Mo3, 13CrMo4-5, 10CrMo9-10, 15NiCuMoNb5-6-4, X20CrMoV11-1): European standards for seamless alloy steel tubes used in high-temperature applications. These tubes are commonly used in boilers, superheaters, and economizers in power plants.
16Mo3: An alloy steel with good high-temperature properties, suitable for use in boilers and pressure vessels.
13CrMo4-5 and 10CrMo9-10: Chromium-molybdenum alloys that offer excellent heat and corrosion resistance for high-temperature applications.

Alloy steel tubes are the go-to option for high-temperature and high-pressure environments where carbon steel may not provide sufficient performance for the Boiler and Heat Exchanger.

IV. Stainless Steel Tubes for Boiler and Heat Exchanger

Stainless steel tubes offer exceptional corrosion resistance, making them ideal for Boiler and Heat Exchanger applications involving corrosive fluids, high temperatures, and harsh environments. They are widely used in heat exchangers, superheaters, and boilers, where, in addition to corrosion resistance, high-temperature strength is also required for optimal performance.

Properties of Stainless Steel:
Corrosion Resistance: Stainless steel’s resistance to corrosion comes from its chromium content, which forms a protective oxide layer on the surface.
High Strength at Elevated Temperatures: Stainless steel maintains its mechanical properties even at high temperatures, making it suitable for superheaters and other heat-intensive applications.
Long-Term Durability: Stainless steel’s resistance to corrosion and oxidation ensures a long service life, even in harsh environments.

Main Standards and Grades:

ASTM A213 / ASTM A249: These standards cover seamless and welded stainless steel tubes for use in boilers, superheaters, and heat exchangers. Common grades include:
TP304 / TP304L (EN 1.4301 / 1.4307): Austenitic stainless steel grades are widely used for their corrosion resistance and strength.
TP310S / TP310MoLN (EN 1.4845 / 1.4466): High-temperature stainless steel grades with excellent oxidation resistance.
TP316 / TP316L (EN 1.4401 / 1.4404): Molybdenum-bearing grades with enhanced corrosion resistance, particularly in chloride environments.
TP321 (EN 1.4541): Stabilized stainless steel grade used in high-temperature environments to prevent intergranular corrosion.
TP347H / TP347HFG (EN 1.4550 / 1.4961): High-carbon, stabilized grades for high-temperature applications such as superheaters and boilers.
UNS N08904 (904L) (EN 1.4539): Super austenitic stainless steel with excellent corrosion resistance, particularly in acidic environments.
ASTM A269: Covers seamless and welded austenitic stainless steel tubes for general corrosion-resistant service.
ASTM A789: Standard for duplex stainless steel tubes, offering a combination of excellent corrosion resistance and high strength.
UNS S31803, S32205, S32750, S32760: Duplex and super duplex stainless steel grades, offering superior corrosion resistance, especially in chloride-containing environments.
EN 10216-5: European standard covering stainless steel seamless tubes, including the following grades:
1.4301 / 1.4307 (TP304 / TP304L)
1.4401 / 1.4404 (TP316 / TP316L)
1.4845 (TP310S)
1.4466 (TP310MoLN)
1.4539 (UNS N08904 / 904L)

Stainless steel tubes are highly versatile and are used in a wide range of applications, including heat exchangers, boilers, and superheaters, where both corrosion resistance and high-temperature strength are not only required but also essential for optimal performance.

V. Nickel-based alloys for Boiler and Heat Exchanger

Nickel-based alloys are among the most corrosion-resistant materials available and are commonly used in Boiler and Heat exchanger applications involving extreme temperatures, corrosive environments, and high-pressure conditions. Nickel alloys provide outstanding resistance to oxidation, sulfidation, and carburization, making them ideal for heat exchangers, boilers, and superheaters in harsh environments.

Properties of Nickel-Based Alloys:
Exceptional Corrosion Resistance: Nickel alloys resist corrosion in acidic, alkaline, and chloride environments.
High-Temperature Stability: Nickel alloys maintain their strength and corrosion resistance even at elevated temperatures, making them suitable for high-temperature applications.
Oxidation and Sulfidation Resistance: Nickel alloys are resistant to oxidation and sulfidation, which can occur in high-temperature environments involving sulfur-bearing compounds.

Main Standards and Grades:

ASTM B163 / ASTM B407 / ASTM B444: These standards cover nickel-based alloys for seamless tubes used in boilers, heat exchangers, and superheaters. Common grades include:
Inconel 600 / 601: Excellent resistance to oxidation and high-temperature corrosion, making these alloys ideal for superheaters and high-temperature heat exchangers.
Inconel 625: Offers superior resistance to a wide range of corrosive environments, including acidic and chloride-rich environments.
Incoloy 800 / 800H / 800HT: Used in high-temperature applications due to their excellent resistance to oxidation and carburization.
Hastelloy C276 / C22: These nickel-molybdenum-chromium alloys are known for their outstanding corrosion resistance in highly corrosive environments, including acidic and chloride-containing media.
ASTM B423: Covers seamless tubes made from nickel-iron-chromium-molybdenum alloys such as Alloy 825, which offers excellent resistance to stress corrosion cracking and general corrosion in various environments.
EN 10216-5: European standard for nickel-based alloys used in seamless tubes for high-temperature and corrosive applications, including grades such as:
2.4816 (Inconel 600)
2.4851 (Inconel 601)
2.4856 (Inconel 625)
2.4858 (Alloy 825)

Nickel-based alloys are often chosen for critical applications where corrosion resistance and high-temperature performance are essential, such as in power plants, chemical processing, and oil and gas refineries Boiler and Heat Exchanger.

VI. Titanium and Zirconium Alloys for Boiler and Heat Exchanger

Titanium and zirconium alloys offer a unique combination of strength, corrosion resistance, and lightweight properties, making them ideal for specific applications in heat exchangers, condensers, and boilers.

Properties of Titanium Alloys:
High Strength-to-Weight Ratio: Titanium is as strong as steel but significantly lighter, making it suitable for weight-sensitive applications.
Excellent Corrosion Resistance: Titanium alloys are highly resistant to corrosion in seawater, acidic environments, and chloride-containing media.
Good Heat Resistance: Titanium alloys maintain their mechanical properties at elevated temperatures, making them suitable for heat exchanger tubes in power plants and chemical processing.
Properties of Zirconium Alloys:
Outstanding Corrosion Resistance: Zirconium alloys are highly resistant to corrosion in acidic environments, including sulfuric acid, nitric acid, and hydrochloric acid.
High-Temperature Stability: Zirconium alloys maintain their strength and corrosion resistance at elevated temperatures, making them ideal for high-temperature heat exchanger applications.

Main Standards and Grades:

ASTM B338: This standard covers seamless and welded titanium alloy tubes for use in heat exchangers and condensers. Common grades include:
Grade 1 / Grade 2: Commercially pure titanium grades with excellent corrosion resistance.
Grade 5 (Ti-6Al-4V): A titanium alloy with enhanced strength and high-temperature performance.
ASTM B523: Covers seamless and welded zirconium alloy tubes for use in heat exchangers and condensers. Common grades include:
Zirconium 702: A commercially pure zirconium alloy with outstanding corrosion resistance.
Zirconium 705: An alloyed zirconium grade with improved mechanical properties and high-temperature stability.

Titanium and zirconium alloys are commonly used in highly corrosive environments such as seawater desalination plants, chemical processing industries, and nuclear power plants Boiler and Heat Exchanger due to their superior corrosion resistance and lightweight properties.

VII. Copper and Copper Alloys for Boiler and Heat Exchanger

Copper and its alloys, including brass, bronze, and copper-nickel, are widely used in heat exchangers, condensers, and boilers due to their excellent thermal conductivity and corrosion resistance.

Properties of Copper Alloys:
Excellent Thermal Conductivity: Copper alloys are known for their high thermal conductivity, making them ideal for heat exchangers and condensers.
Corrosion Resistance: Copper alloys resist corrosion in water, including seawater, making them suitable for marine and desalination applications.
Antimicrobial Properties: Copper alloys have natural antimicrobial properties, making them suitable for applications in healthcare and water treatment.

Main Standards and Grades:

ASTM B111: This standard covers seamless copper and copper-alloy tubes for use in heat exchangers, condensers, and evaporators. Common grades include:
C44300 (Admiralty Brass): A copper-zinc alloy with good corrosion resistance, particularly in seawater applications.
C70600 (Copper-Nickel 90/10): A copper-nickel alloy with excellent corrosion resistance in seawater and marine environments.
C71500 (Copper-Nickel 70/30): Another copper-nickel alloy with higher nickel content for enhanced corrosion resistance.

Copper and copper alloys are widely used in marine Boiler and Heat Exchanger applications, power plants, and HVAC systems due to their excellent thermal conductivity and resistance to seawater corrosion.

In addition to the boiler and heat exchanger, condensers, superheaters, air preheaters, and economizers are also vital components that significantly optimize energy efficiency. For instance, the condenser cools the exhaust gases from both the boiler and heat exchanger, while the superheater, on the other hand, increases the steam temperature for improved performance. Meanwhile, the air preheater utilizes exhaust gases to heat incoming air, thereby further enhancing the overall efficiency of the boiler and heat exchanger system. Lastly, economizers play a crucial role by recovering waste heat from flue gases to preheat water, which ultimately reduces energy consumption and boosts the efficiency of both the boiler and heat exchanger.

VIII. Conclusion: Choosing the Right Materials for the Boiler and Heat Exchanger

Seamless tubes are integral to the performance of boilers, heat exchangers, condensers, superheaters, air preheaters, and economizers in industries such as power generation, oil and gas, and chemical processing. The choice of material for seamless tubes depends on the specific application requirements, including temperature, pressure, corrosion resistance, and mechanical strength.

Carbon steel offers affordability and strength for moderate temperature and pressure applications.
Alloy steel provides superior high-temperature performance and strength in boilers and superheaters.
Stainless steel delivers excellent corrosion resistance and durability in heat exchangers and superheaters.
Nickel-based alloys are the best choice for extremely corrosive and high-temperature environments.
Titanium and zirconium alloys are ideal for lightweight and highly corrosive applications.
Copper and copper alloys are preferred for their thermal conductivity and corrosion resistance in heat exchangers and condensers.

Boiler and heat exchanger systems play a crucial role in various industries by efficiently transferring heat from one medium to another. A boiler and heat exchanger work together to generate and transfer heat, providing essential heat for steam production in power plants and manufacturing processes.

By understanding the properties and applications of these materials, engineers and designers can make informed decisions, ensuring the safe and efficient operation of their equipment. When selecting materials for the Boiler and Heat Exchanger, it is crucial to consider the specific requirements of your application. Additionally, you should consult the relevant standards to ensure compatibility and optimal performance.

How to Select Materials: Material Selection Guidelines

October 12, 2024/in Industry Knowledge/by Energy Steel

Introduction

Material selection is a critical step in ensuring the reliability, safety, and performance of equipment across industries such as oil and gas, chemical processing, marine engineering, aerospace, and many more. The right material can prevent corrosion, withstand extreme temperatures, and maintain mechanical integrity in harsh environments. Steels and alloys such as carbon steels, alloy steels, stainless steels, nickel, titanium, and various high-performance superalloys like Inconel, Monel, and Hastelloy offer specific advantages that make them ideal for these demanding applications. This blog provides a comprehensive overview of material selection guidelines, focusing on key materials and their suitability based on corrosion resistance, mechanical properties, and temperature capabilities. By understanding these properties, engineers and decision-makers can optimize material selection to ensure long-term performance and operational efficiency.

Material Selection Guidelines: Table 1 – List of Abbreviations

Abbreviations
API	American Petroleum Institute
ASTM	American Society for Testing and Material
CA	Corrosion Allowance
CAPEX	Capital Expenditures
CO2	Carbon Dioxide
CMM	Corrosion Monitoring Manual
CRA	Corrosion-Resistant Alloy
CRAS	Corrosion Risk Assessment Study
Cr Steel	Chrome Stainless Steel
22Cr	Duplex Stainless Steel type 2205 (for example UNS S31803/S32205)
25Cr	Super duplex stainless steel 2507 (for example UNS S32750)
CS	Carbon Steel
CTOD	Crack Tip Opening Displacement
DSS	Duplex Stainless Steels
ENP	Electroless Nickel Plating
EPC	Engineering, Procurement, and Construction
GRP	Glass Reinforced Plastic
HAZ	Heat Affected Zone
HV	Vickers Hardness
HIC	Hydrogen-Induced Cracking
H2S	Hydrogen Sulphide
ISO	International Organization of Standardization
LTCS	Low-Temperature Carbon Steel
MCA	Materials and Corrosion Audit
MSDs	Materials Selection Diagrams
MSR	Material Selection Report
N.A.	Not Applicable
NACE	National Association of Corrosion Engineers
OPEX	Operating Expenditures
PFDs	Process Flow Diagrams
pH	Hydrogen Number
PMI	Positive Material Identification
PREN	Pitting Resistance Equivalent Number = %Cr + 3.3 (%Mo+0.5 %W) + 16 %N
(C-)PVC	(Chlorinated) Polyvinyl Chloride
PWHT	Post-Weld Heat Treatment
QA	Quality Assurance
QC	Quality Control
RBI	Risk-based inspection
SAW	Submerged arc welded
SDSS	Super Duplex Stainless Steel
SOR	Statement of Requirement
SOW	Scope of Work
SS	Stainless Steel
WPQR	Welding Procedure Qualification Record
UFDs	Utility Flow Diagrams

Material Selection Guidelines: Table 2 – Normative References

Ref.	Document No.	Title
(1)	ASTM A262	Standard practice for detecting susceptibility to intergranular attack
(2)	NACE MR0175 / ISO 15156	Petroleum, petrochemical and natural gas industries – Materials for use in H2S-containing environments in oil and gas production
(3)	NACE SP0407	Format, content, and guidelines for developing a materials selection diagram
(4)	ISO 21457	Petroleum, petrochemical and natural gas industries – Materials selection corrosion control for oil and gas production systems
(5)	NACE TM0177	Laboratory testing of metals for resistance to sulfide stress cracking and stress corrosion
(6)	NACE TM0316	Four-point bend testing of materials for oil and gas applications
(7)	NACE TM0284	Standard test method – evaluation of pipeline and pressure vessel steels for resistance to hydrogen-induced cracking
(8)	API 6DSS	Specification for subsea pipeline valves
(9)	API RP 945	Avoiding environmental cracking in Amine units
(10)	API RP 571	Damage mechanisms affecting fixed equipment in the refining industry
(11)	ASTM A263	Standard specification for stainless chromium steel-clad plate
(12)	ASTM A264	Standard specification for stainless chromium-nickel steel-clad plate
(13)	ASTM A265	Standard specification for nickel and nickel-base alloy-clad steel plate
(14)	ASTM A578	Standard specification for straight-beam ultrasonic examination of rolled steel plates for special applications
(15)	ASTM A153	Standard Specification for Zinc coating (hot-dip) on iron and steel hardware
(16)	NACE MR0103/ISO 17945	Petroleum, petrochemical and natural gas industries – Metallic materials resistant to sulfide stress cracking in corrosive petroleum refining environments
(17)	ASTM A672	Standard specification for electric-fusion-welded steel pipe for high-pressure service at moderate temperatures
(18)	NACE SP0742	Methods and controls to prevent in-service environmental cracking of carbon steel weldments in corrosive petroleum refining environments
(19)	API 5L	Specification for Line Pipe
(20)	NACE SP0304	Design, installation, and operation of thermoplastic liners for oilfield pipelines
(21)	DNV RP O501	Erosive wear in piping systems

Material Selection Guidelines: Table 5 – Parameters Used for Corrosion Evaluation

Parameter	Units
Design Life	Years
Operating Temperature Range	°C
Pipe Diameter	mm
Design Pressure	MPa
Dewpoint Temperature	°C
Gas to Oil Ratio (GOR)	SCF / SBO
Gas, Oil & Water Flow Rate	tonnes/day
CO2 Content & partial pressure	Mole % / ppm
H2S Content & partial pressure	Mole % / ppm
Water Content	%
pH	N.A.
Chloride Content	ppm
Oxygen	ppm/ppb
Sulfur	wt% / ppm
Mercury	wt% / ppm
Acetic Acid Concentration	mg/l
Bicarbonate Concentration	mg/l
Calcium Concentration	mg/l
Sand/Solid Particle Content (Erosion)	kg/hour
Potential for Microbially Induced Corrosion (MIC)	N.A.

It is COMPANY policy to use Carbon Steel (CS) whenever possible for the construction of production systems, processing equipment and pipelines. A Corrosion Allowance (CA), adequate for the asset to achieve the required service life is provided to accommodate corrosion (Section 11.2), and wherever feasible, corrosion inhibition (Section 11.4) is supplied to reduce the risk of pitting and reduce the rate of corrosion.

Where the use of CS is not a technical and economic option and/or where a failure by corrosion would pose an acceptable risk to personnel, the environment, or COMPANY assets, Corrosion Resistant Alloy (CRA) may be used. Alternatively, if the service life corrosion of CS with inhibitor treatment exceeds 6 mm, CRA will be selected (Solid or Clad CRA). Selection of a CRA should ensure that the optimum alloy is selected based on cost-performance criteria. A material selection flow diagram is shown in Figure 1 to outline the process by which material selection alternate to CS may be justified.

Figure 1 – Material Selection Flow Diagram

Material Selection Guidelines: Corrosion Allowance

CA, for CS, shall be specified based on anticipated corrosion rates or material degradation rates under the most severe combination of process parameters. Specifying CA should be properly engineered and justified noting that when short-term material performance or transient conditions are anticipated to increase general or localized corrosion risks, upset duration shall be estimated based on prorated corrosion rates. Based on these, extra corrosion allowances may be required. Therefore, the CRAS needs to be carried out at an early stage of the project.

The CA itself shall not be considered as an assured corrosion control measure. It shall be considered only as a measure to provide time to detect measure and assess the rate of corrosion.

Depending on the Project’s requirements and conditions, the permittable CA can be increased above 6 mm where the estimated corrosion rate exceeds 0.25 mm/y. However, this will be discussed on a case-by-case basis. When corrosion allowances are excessive, material upgrades shall be considered and evaluated. The selection of CRA should ensure that the optimum alloy is selected based on the cost-performance criterion.

The following guidelines shall be used to specify the level of CA:

The CA is the product of multiplying the estimated corrosion rate of the selected material by the design life (including possible life extension), rounded to the nearest 3.0, 4.5 or 6.0 mm.
Corrosion due to CO2 can be assessed using COMPANY-approved corrosion models such as ECE- 4 & 5, Predict 6.
The corrosion rate used to estimate the CA shall be based on past plant experience and the available published data for process conditions which should include:
- Corrosivity of fluid, for example, the presence of water combined with hydrogen sulfide (sour corrosion), CO2 (sweet corrosion), oxygen, bacteriological activity, temperature and pressures;
Velocity of fluid that determines the flow regime in the pipeline;
Deposition of solids that may prevent adequate protection by inhibitors and create conditions for the growth of bacteria; and
Conditions that may cause pipe wall
CS and low alloy steel of pressure parts shall have a minimum of 3.0 mm. In special cases 1.5 mm may be specified with COMPANY approval; considering the design life of the item under consideration. Examples of mild or non-corrosive services, where 5 mm CA may be specified, are steam, deaerated boiler feed water (< 10 ppb O2), treated (non-corrosive, chloride controlled, bacteria free) fresh cooling water, dry compressed air, hydrocarbons containing no water, LPG, LNG, dry natural gas, etc. Nozzles and manhole necks shall have the same CA as specified for the pressure-containing equipment.
Maximum CA shall be 6.0 mm. Depending on the Project’s requirements and conditions, the permittable CA can be increased above 6 mm where the estimated corrosion rate exceeds 0.25 mm/y. However, this will be discussed on a case-by-case basis. When corrosion allowances are excessive, a material upgrade shall be considered and the Selection of CRA should ensure that the optimum alloy is selected based on the cost-performance criterion.
The layout of the installation and its effect on the flow rate (including dead legs).
Failure probabilities, failure modes, and failure consequences for human health, environment, safety, and material assets, are all determined by carrying out a risk assessment not only for Materials but for other disciplines as well.
Access to maintenance and

For the final materials selection, the following additional factors shall be included in the evaluation:

Priority shall be given to materials with good market availability and documented fabrication and service performance, for example, weldability, and inspection ability;
The number of different materials shall be minimized considering stock, costs, interchangeability, and availability of relevant spare parts;
Strength to weight (for offshore); and
Frequency of pigging/cleaning. No CA shall be required for:
The backing material of items with alloy cladding or weld
On the gasket facing of
For CRAs. However, for CRAs in erosive service, a 1 mm CA shall be specified. This shall be addressed and supported by erosion modelling via DNV RP O501 [Ref. (e)(21)] (or similar models when approved for use by the COMPANY).

Note: When short-term or transient conditions are anticipated to increase general or localized corrosion risks, upset duration shall be estimated based on prorated corrosion rates. Based on these, higher corrosion allowances may be required. Additionally, CRA piping or CRA internally clad/lined piping shall be used for areas of high fluid velocity and expected erosion-corrosion.

Material Selection Guidelines: Metallic Cladding

To mitigate the risk of corrosion where corrosion rates are over a 6 mm CA, it may be suitable to specify a CS parent material with a layer of CRA cladding or weld overlay material. Where there is any doubt the specifier of materials shall seek advice from COMPANY. Where CRA cladding of vessels is specified or CRA cladding is applied by explosive weld bonding, metallic roll bonding, or weld overlay, SSC resistant quality base plate is required, but HIC resistant base plate is not required.

If explosion bonding or roll bonding is the selected option, a minimum thickness of 3 mm shall be achieved across 100% of the parent material. If overlay is the selected option, there should be a minimum of 2 passes and a minimum thickness of 3 mm shall be achieved. If there is a weldability issue, then explosive bonding can be considered.

Common cladding materials include:

316SS (type 317SS may be specified where there is a higher risk of chloride pitting);
Alloy 904;
Alloy 825 (limited to roll bonding as welding may result in inferior corrosion resistance in clad plate); and
Alloy

Where the thickness of the vessel is relatively thin (up to 20 mm), a lifecycle cost analysis shall be used to decide whether a solid CRA material selection is more commercially viable. This shall be considered on a case-by-case basis.

Clad or lined pipe may be used for flowlines that transport highly corrosive fluids. The requirements of API 5LD apply. For economic reasons, these pipelines will be of modest diameter and short length. Clad pipe is formed from a steel plate that has a 3 mm layer of CRA bonded to its internal surface. The CRA clad can be either metallurgically bonded, co-extruded, or weld overlaid, or for subsea applications, process/mechanical bonding can be used when depressurizing risk is low. For welded pipe specification CRA cladded pipe is formed to the pipe and the seam is welded with CRA consumables.

The CONTRACTOR shall issue separate specifications based on existing COMPANY-specific specifications for alloy clad or weld overlay on CS, covering the requirements for the design, fabrication, and inspection of applied lining and integral cladding for pressure vessels and heat exchangers. The ASTM specifications A263, A264, A265, A578, and E164, and NACE MR0175/ISO 15156 may be used for reference.

Material Selection Guidelines: Application of Corrosion Inhibitor

Selection of corrosion inhibitor and evaluation shall be as per the Company’s Procedure. For design purposes, 95% corrosion inhibition efficiency shall be assumed for gas condensate and 90% for oil. Additionally, during design, the inhibitor availability shall be based on 90% availability, during the operational phase the minimum inhibitor availability shall be >90%. The inhibitor availability shall be specified during the FEED stage on a project-to-project basis. However, the use of corrosion inhibitors shall not act as a substitute for NACE MR0175/ISO 15156 sour service material selection requirements.

To enable the effectiveness of the inhibition system to be verifiable during operation, the following shall be included in the design:

The locations of the highest potential corrosion
Accessibility of high potential corrosion rate locations for wall thickness measurement during
Ability to take samples for solids/debris
Corrosion measurement equipment should be used to monitor the effectiveness of the inhibition
Facilities to allow iron counts should be included in the design for monitoring inhibited

Provision shall be made in the design so that the following Key Performance Indicators (KPI) can be measured and trended for inhibited systems:

The number of hours the inhibition system is not
Actual injected concentration compared with target injection
Inhibitor residual concentration compared to target
Average corrosion rate as compared to target inhibited corrosion
Changes in corrosion rate or dissolved iron levels as a function of
Unavailability of corrosion monitoring

Material Selection Guidelines: Material for Sour Service

Materials selection for piping and equipment for use in H2S-containing environments shall comply with the latest COMPANY Specification for Materials in Sour Environments and be verified to NACE MR0175/ISO15156 for upstream processes and NACE MR0103/ISO 17945 for downstream processes.

316L SS shall be considered for most sour services except where higher temperatures >60 °C occur together with a high H2S and chloride content of the fluid, however, this will be considered on a case-by-case basis. For operating conditions outside of these limitations, higher alloy materials may be considered in compliance with NACE MR0175/ISO15156. Additionally, consideration should be given to vapor separation where the chloride content carryover will be reduced.

316L SS cladding may be considered for vessels when following the environmental and materials limits from Table A2 in ISO 15156, part 3. Vessels clad with 316L must be allowed to cool below 60 °C before opening as there is a risk of chloride stress cracking of the cladding when exposed to oxygen. For operating conditions outside of these limitations, higher alloy materials may be considered in compliance with NACE MR0175/ISO15156. Cladding shall be inspected to ensure that it is continuous over 100% of the complete surface including any nozzles and any other attachments.

Steel for sour service piping shall be HIC resistant have a sulfur content <0.01% and be secondary treated with calcium for inclusion shape control. Steel for longitudinally welded pipe shall have a sulfur content <0.003% and be secondary treated with calcium for inclusion shape control.

Specific guidelines for bolting in sour service environments can be found in the bolting section of this guideline; Section 12.8.

When sour service requirements are specified by the purchaser, the following shall apply:

All materials shall be marked to ensure full traceability to melt and heat treatment
Heat treatment For tempered conditions, tempering temperature shall be stated.
The supplementary suffix ‘S’ shall be used to designate a material delivered in accordance with the MDS plus the additional supplementary requirements for sour service excluding HIC testing and UT examination.
The supplementary suffix ‘SH’ shall be used to designate a material delivered in accordance with the MDS including the additional supplementary requirements for sour service plus HIC testing and UT
The material manufacturer shall have a quality system certified in accordance with ISO 9001 or another quality requirements standard accepted by the purchaser.
The inspection documents shall be issued in accordance with ISO 10474 /EN 10204 Type 1 and shall confirm compliance with this specification.
Fully killed materials must be
For sour service pipe, materials shall comply with the requirements of API 5L Annex H – PSL2. For severe sour service, low strength normalized grades are specified, limited up to X65 grades.
Sour service testing is required on both base material and weldments and routine testing for SSC and HIC shall accord with NACE TM0177 and NACE TM0284. Testing for SOHIC and soft zone cracking may require full ring testing with the welds produced using the actual manufacturing weld Four-point bend testing shall be carried out in accordance with NACE TM0316.
Hardness as per ISO 15156 for upstream, and NACE MR0173/NACE SP0742 for

Material Selection Guidelines: Specific Considerations

The following list contains specific material selection considerations that are not specific to any given system and shall be applied to all COMPANY Projects:

The CONTRACTOR shall be fully responsible for the material selection made by any LICENSOR I in any packaged equipment. The CONTRACTOR shall provide for all information including MSDs, material selection philosophies, CRAS, RBI, and MCA in line with this specification for COMPANY approval. Any change of material will be warranted under the CONTRACTOR.
Attention shall be given to the fracture toughness properties of pipe materials to prevent the possibility of brittle fracture.
Aluminum bronze material shall not be used in welded parts because of poor weldability and maintenance problems.
Electroless Nickel Plating (ENP) shall not be used unless approved by
Material for the Lube and Seal Oil system shall be SS316L if its suitability is
Rubber linings in water boxes of surface condensers and other exchangers shall not be used without COMPANY approval.
Use of GRE/HDPE material for low-pressure oil and gas, water, oily, and stormwater, drains within acceptable service parameters and loading (when buried) limits by manufacturer is permitted with COMPANY’s approval.
The design of any heat exchangers shall be based on their process requirements. Therefore, material selection is bespoke for all heat exchangers and cannot/should not be standardized.
Stainless steel 304, 304L shall not be used as an external material application where it’s not suitable for the humid laden atmosphere of UAE.

FBE Coated Pipeline

Material Selection Guidelines: Specific Applications and Systems

This section gives material guidelines for specific systems that are present within the COMPANY’s range of facilities including its upstream (both onshore and offshore) and downstream (refinery) assets. An overview

of the units found within these facilities, the material options, potential damage mechanisms, and mitigation for such mechanisms are given in the following tables. Further detail for each unit is given throughout the remainder of this Section. For further details on the listed corrosion mechanisms, see API RP 571.

Note: Material options given in this section shall be taken as a guideline only. The CONTRACTOR shall be responsible for project-specific material selection throughout each phase of the Project through the deliverables specified in Section 10.

Material Selection Guidelines: Table 6 – Material Recommendations for Upstream Process Equipment and Piping

Service	Material Options	Damage Mechanisms	Mitigation
Wellhead rigid spools/Jumper and Manifolds	CS+CRA Cladding, CRA, CS+CA	CO2 corrosion, Wet H2S Damage, Chloride Stress Corrosion Cracking (CSCC)	Material Selection. (When Corrosion Inhibition is deemed ineffective at such locations/highly corrosive service/CRA clad option recommended) Design for sour service. UNS N06625/UNS N08825 clad option. NACE MR0175/ISO 15156 sour service requirements apply for sour service.
Pipeline/Flowline	CS+CA	Hydrogen embrittlement, CO2 corrosion, Wet H2S Damage, CSCC, MIC	Cathodic protection and coating to protect buried metallic section. Use of biocide corrosion inhibitor, and pig/scrapper. Periodic Inline Inspection (Intelligent Pigging) to measure wall thickness and periodic cleaning using appropriate cleaning pig.
Wet Hydrocarbon Gas	CS+CA (+CA/CRA Cladding), 316SS, DSS, SDSS	CO2 corrosion, Wet H2S Damage, CSCC, chloride pitting,	Material Selection Design for sour service TOL corrosion is to be assessed, and mitigation is to specify CRA clad when corrosion allowance exceeds 6mm. Use of corrosion inhibitor NACE MR0175 /ISO 15156 sour service requirements apply for sour service. Selection at the inlet is predominantly based on sour service requirements
Dry Hydrocarbon Gas	CS+CA (+CRA Cladding), 316SS	CO2 corrosion, Wet H2S Damage.	Material Selection Ensure operation is within specified conditions envelope Corrosion monitoring is vital to ensure gas remains dry. CA may be required if periods of wetness are possible.
Stabilized Condensate	CS+CA	CO2 corrosion, Wet H2S Damage, MIC	Material Selection Monitoring of bacterial activity
Produced Water	CS+CA, 316SS, DSS, SDSS. CS+CRA liner, CS+CRA (metallurgical bonded)	CO2 Corrosion, Wet H2S Damage, CSCC, MIC, O2 corrosion	Material selection Design to prevent oxygen ingress Use of biocide, O2 scavenger, and corrosion inhibitor CS + internal lining may be selected for vessels. Specification of pipe material is highly dependent on process/fluid conditions. NACE MR0175 /ISO 15156 sour service requirements apply for sour service.
Export Oil/Gas Export/Feed Gas	CS+CA	CO2 corrosion, Wet H2S Damage, MIC	Material Selection For Gas export Dew point temperature monitoring If gas export is considered ‘wet’, an upgrade to CRA (clad /solid) material may be required based on corrosion assessment results.
Gas Dehydration (TEG)	CS+CA, 316SS, CS+CRA	Corrosion from acid condensation in still column overheads	Material selection is licensor-driven; however, the responsibility lies with the CONTRACTOR.
Injection Chemicals (for example corrosion inhibitors)	CS(+CA), 316SS, C-PVC	Chemical compatibility, corrosion.	Materials selection shall be discussed with VENDOR/SUPPLIER in terms of chemical compatibility.
Mercury Removal	CS+CA	CO2 corrosion, Wet H2S Damage, CSCC, chloride pitting *Liquid metal embrittlement	Material selection *Aluminium or copper-bearing titanium alloys shall not be used where there is a risk of liquid mercury.
Amine	CS+CA/CRA Cladding, 316SS	CO2 corrosion, wet H2S damage, Amine Stress Corrosion Cracking (ASCC), amine corrosion, erosion (from heat-stable salts)	Suitable operation velocities, temperatures for the designed system, and regular sampling to check for amine salts. Rich amine shall be 316SS. The vessel’s internal shall be 316SS. Velocity limits. PWHT shall be specified for CS to prevent ASCC when the design temperature is > 53°C. PWHT temperature to be used shall be as per API RP945.
Flare	CS+CA, 316SS *310SS, 308SS, Alloy 800, Alloy 625	Low-temperature fracture, atmospheric corrosion, creep rupture (thermal fatigue), CSCC.	CS + lining is an option for flare drums Design for both minimum and maximum design temperature Issue of low-temperature brittle fracture to be addressed. Internal corrosion mechanisms are more likely in marine environments. * materials for flare tip.
PLR (PIG Launcher Receiver)	CS+Weld overlay for sealing surface	CO2 corrosion, Wet H2S Damage, under-deposit corrosion, MIC, Dead Leg Corrosion	Material selection Periodic Inspection Use of biocide and corrosion inhibitor.

Table 7 – Material Recommendations for Downstream Process Equipment and Piping

Service	Material Options	Damage Mechanisms	Mitigation
Crude Oil Unit	CS, 5Cr-1/2 Mo, 9Cr-1Mo, 12Cr, 317L, 904L, or other alloys with higher Mo (to avoid NAC), CS+SS Clad	Sulfur attack, Sulfidation, naphthenic acid corrosion (NAC), wet H2S damage, HCL corrosion	Material Selection Desalting Flow velocity limit. Use of corrosion inhibitor
Fluid Catalytic Cracking	CS + CA, 1Cr-1/2Mo, 2-1/4Cr-1Mo, 5Cr and 9Cr Steels, 12Cr SS, 300 series SS, 405/410SS, alloy 625 Internal erosion/insulating refractory linings	Catalyst Erosion High-Temperature Sulfidation, High-Temperature Carburisation, Creep, Creep embrittlement, Ploythionic Acid Stress corrosion cracking. High-temperature graphitization, High-temperature oxidation. 885°F Embrittlement.	Material selection Erosion-resistant lining Design minimum turbulence of catalyst and catalyst carryover
FCC Light End Recovery	CS + CA (+ 405/410SS Cladding), DSS, alloy C276, alloy 825	Corrosion caused by the combination of aqueous H2S, ammonia, and hydrogen cyanide (HCN), Wet H2S damage-SSC, SOHIC, HIC ammonium stress corrosion cracking, carbonate stress corrosion cracking	Material selection Polysulfide injection into wash water to lower HCN content. Velocity limit Corrosion inhibitor injection. Prevention of oxygen ingress
Sulphuric Acid Alkylation	CS + CA, Low Alloy Steel, alloy 20, 316SS, C-276	Sulphuric acid corrosion, Hydrogen grooving, acid dilution, fouling, CUI.	Material selection – however higher alloys are uncommon Velocity control (CS- 0.6m/s – 0.9m/s, 316L limited to 1.2m/sec) Acid Tanks as per NACE SP0294 Antifouling injection
Hydro-processing	CS, 1Cr-1/2Mo, 2-1/4Cr-1Mo, 18Cr-8Ni SS, 316SS, 321, 347SS, 405/410SS, alloy 20, alloy 800/825, Monel 400	High-Temperature Hydrogen Attack (HTHA), Sulfidation by Hydrogen-H2S mixtures, Wet H2S damage, CSCC, naphthenic acid corrosion, ammonium bisulfide corrosion.	Material selection as per API 941- HTHA. Velocity control (high enough to maintain fluid distribution) PWHT as per ASME VIII / B31.3
Catalytic Reforming	1-1/4Cr-0.5Mo, 2-1/4Cr-0.5Mo,	Creep cracking, HTHA, SSC- Ammonia, SSC- chlorides, hydrogen embrittlement, ammonium chloride corrosion, creep rupture	Material selection as per API 941- HTHA. Hardness control, PWHT
Delayed Coker	1-1/4Cr-.0.5Mo clad with 410S or 405SS, 5Cr-Mo or 9Cr-Mo steels, 316L, 317L	High-temperature sulfur corrosion, naphthenic acid corrosion, High-Temperature oxidation/carburization/sulfidation, Erosion- corrosion, Aqueous corrosion (HIC, SOHIC, SSC, Ammonium chloride/ bisulfite, CSCC), CUI, Thermal Fatigue (thermal cycling)	Minimise stress raisers, Cr-Mo steel of Fine grain, Good toughness properties.
Amine	CS + CA / CS+ 316L Cladding, 316SS	CO2 corrosion, wet H2S damage, Amine Stress Corrosion Cracking (ASCC), rich amine corrosion, erosion (from heat-stable salts)	See Amine in Table 6.
Sulphur Recovery (Licensed Units)	CS, 310SS, 321SS, 347SS,	Sulfidation of carbon steel, Wet H2S damage/ cracking, (SSC, HIC, SOHIC), weak acids corrosion,	Operating piping above dew point temperature to avoid severe corrosion of CS. PWHT of welds to avoid cracking Hardness control HIC-resistant steel.

Pipelines

Pipeline material will be in accordance with existing COMPANY-specific Pipeline Material Specifications. Carbon steel + corrosion allowance shall be the default material. The corrosion allowance shall be as high as possible as consideration for operation well beyond the design life and will be decided on a case-by-case basis on each Project. Pipeline coatings are specified in AGES-SP-07-002, the External Pipeline Coatings Specification.

The use of corrosion inhibitors in hydrocarbon pipeline systems with condensed water is recommended and shall be the default option for sub-sea pipelines. i.e. CS + CA + Corrosion Inhibitor. Additional corrosion management techniques such as Pigging, CP, etc. shall be considered. Selection and evaluation of corrosion inhibitors shall be as per the Company’s procedure.

The selection of a CRA option for the pipeline must be evaluated thoroughly via Life Cycle Costing analysis. HSE considerations of cost of chemicals and corrosion management techniques, logistics of transporting and handling chemicals, shall all be built into the analysis, as well as inspection requirements.

Hydrocarbon Piping

Material selection for process piping shall be performed by the CONTRACTOR as per the requirements of Section 11. Material guidelines per service are given for both upstream and downstream facilities in the prior table 6 and 7, respectively. All welds and acceptance criteria shall be conducted according to the requirements of ASME B31.3. Piping material shall be specified by piping in conformance to ADNOC piping material specification AGES-SP-09-002.

Particular and separate material selection may be required for dead legs whereas a CRA or CRA cladding may be required for corrosion control in areas of stagnant flow. However, the piping design should consider avoiding dead legs to reduce the probability and severity of corrosion. Where dead legs cannot be avoided, internal coating, dosing with inhibitors and biocides, and periodic corrosion monitoring are recommended. This is also applicable to static equipment.

During design, care shall be taken, particularly by piping discipline, not to have SS in contact with galvanized parts, to avoid zinc embrittlement. This is a concern at temperatures where Zn can diffuse, such as in welding operations.

Utility Systems

Material Selection Guidelines: Table 8 – Material Selection Guidelines for Utility Services

Service	Material Options	Damage Mechanisms	Mitigation
Fuel Gas	CS, 316SS	If fuel gas is wet: CO2 corrosion, chloride pitting, CSCC, wet H2S damage	Material Selection Controlled operation conditions during start-up when alternate fuel gas may be used.
Inert Gas	CS + min. CA	General contaminants from fuel gas product	Material selection (level corrosion is dependent on what inert gas is used, for example, fuel gas from exhaust.)
Diesel Fuel	CS + CA, 316SS,CS + CA+ Lining *Cast Iron	Risk of contaminants	CS + Lining is suitable for tanks *Pumps shall be cast iron.
Instrument/Plant Air	Galvanized CS, 316 SS	Atmospheric corrosion	Controlled filtration
Nitrogen	Galvanized CS, 316SS	None, corrosion may come from O2 ingress during blanketing operations	Upgrade spec where ingress is more likely, or cleanliness is required
Hypochlorite	CS + PTFE lining, C-PVC, C-276, Ti	Crevice corrosion, oxidization	Material selection Dosing/temperature control
Sewage	316 SS, GRP	Chloride Pitting, CSCC, CO2 corrosion, O2 corrosion, MIC	Material selection
Fresh Water	Epoxy-coated CS, CuNi, Copper, Non-metallic	O2 corrosion, MIC	Cleanliness monitoring/use of biocide if not used for potable water
Cooling Water	CS + CA, Non-metallic	Cooling water corrosion	Use of O2 scavenger and corrosion inhibitor Mixed glycol-water cooling systems in contact with CS components are known to cause corrosion. Glycol should be mixed with a corrosion inhibitor.
Seawater	CS + lining, SDSS, Alloy 625, Ti, CuNi, GRP	Chloride Pitting, CSCC, O2 corrosion, crevice corrosion, MIC	Material selection Temperature control
Demineralized Water	Epoxy-coated CS, 316SS, Non-metallic	O2 corrosion	Material selection
Potable Water	Non-metallic (for Example C-PVC/HDPE), Cu, CuNi, 316 SS	MIC	Sacrificial anodes shall not be used in potable water systems.
Firewater	CuNi, CS+3mmCA(minimum)+internal coating, GRVE, GRE, HDPE	Chloride Pitting, CSCC, O2 corrosion, crevice corrosion, MIC	Corrosion mechanisms dependent on firewater medium. The non-metallic option needs to consider fire hazard risk
Open Drains	Non-metallic CS + epoxy lining	Chloride Pitting, CSCC, O2 corrosion, crevice corrosion, MIC, atmospheric corrosion	Piping from clad vessels shall be CRA.
Closed Drains	CS + CA, 316SS, DSS, SDSS, CS +CRA Clad	CO2 corrosion Wet H2S Damage, CSCC, crevice corrosion, O2 corrosion, ASCC, MIC	Material selection

Fuel Gas

Fuel gas is either supplied as dried gas from downstream of the dehydration columns, like export gas, or as separated low-pressure gas that is not completely dried and may be heated to prevent water condensation in the delivery piping.

Dried gas will be transported in CS pipes with a nominal CA of 1 mm and will not be inhibited. Depressurization temperature must be analyzed, and if it is lower than -29 °C, low-temperature CS must be specified. Undried fuel gas should be treated similarly to produced wet gas (anything <10 °C above the dewpoint). If cleanliness is required, then 316 SS should be specified.

Inert Gas

Considered noncorrosive. See Table 8.

Diesel Fuel

Considered non-corrosive and CS is suitable, however, may contain some contamination depending on diesel quality. In such cases, diesel storage tanks fabricated in CS with a 3 mm CA shall be required to be internally coated to prevent corrosion and precipitation of corrosion products into the diesel that may interfere with equipment. The complete tank should be coated as condensation on the upper surface can also produce corrosion products. The alternative is to use tanks fabricated from a non-metallic such as GRP.

Instrument/Plant Air & Nitrogen

Galvanized CS is commonly used for high-quality air and nitrogen systems for larger-diameter piping and 316 SS for smaller-diameter piping, despite its non-corrosiveness. Where ingress of moisture may be present, or cleanliness is required downstream of any filters, the alternative option of 316 SS shall be considered throughout. DSS connectors and fittings should be used.

Fresh Water

If treated (as defined in Section 11.2), CS with a CA is allowable. If untreated, freshwater systems should be upgraded to a suitable CRA or CS with CRA cladding.

Potable water should be stored in CS tanks that are internally coated with a coating acceptable to health standards or in tanks fabricated from GRP. When GRP tanks are used the tanks must be externally coated to prevent light entry into the tanks and algal growth in the stored water. To prevent from degradation of the external coating, UV-resistant grades must be specified. Piping should be non-metallic materials and conventional copper piping when of the appropriate diameter. Alternatively, 316 SS may be specified for cleanliness reasons.

Seawater

Material selection for seawater systems is highly dependent on temperature and should be selected with reference to ISO 21457. Recommended materials are included in Table 8. CS with internal lining shall only be selected for de-aerated seawater systems as per API 15LE and NACE SP0304.

For firewater systems using seawater as a medium, see Section 12.3.8.

Demineralized Water

Demineralized water is corrosive to CS; hence these systems should be 316 SS. A non-metallic may be selected with input from the material MANUFACTURER and approval from the COMPANY is given. Tanks may be CS with a CA and a suitable internal lining.

Firewater

For most permanently wetted firewater systems with seawater as the medium, the material recommendation is 90/10 CuNi or titanium (refer to the Utility Table 8 in ISO 21457).

Firewater systems may contain, and transport aerated fresh water. The above-ground mains may be constructed from 90/10CuNi and the underground mains may be constructed from GRVE (Glass Reinforced Vinyl Esther) which does not require coating or cathodic protection. Larger valves should be CS with CRA clad for internal wetted surfaces and CRA trim. Critical valves will require to be fully fabricated from CRA materials. To avoid galvanic corrosion issues isolation spools shall be specified wherever electrical isolation between dissimilar materials is required.

NiAl bronze valves are compatible with 90/10CuNi piping, however, NiAl Bronze and CuNi are unsuitable for sulfide-polluted water.

The selection of material will depend on the quality of the water and its temperature. Black body temperature must be considered in the design.

Internally epoxy-coated carbon steel piping for the firewater system is subject to COMPANY approval.

Open Drains

Material selection for open drains equipment shall be CS with an internal lining. The recommendation for piping is an appropriate non-metallic pending COMPANY approval. Alternatively, CS with a 6 mm CA may be specified when the service has low criticality. Open drain tanks shall be internally lined by a qualified organic coating system and supplemented with a Cathodic Protection system.

Closed Drains

Material selection for closed drains shall consider the conditions of any potential hydrocarbons within the system. Where closed drains receive sour hydrocarbon, the requirements for sour service (as per Section 11.5) shall apply. The design of the blanketing system for all drums and tanks shall consider the possibility of residual oxygen, and therefore be considered within the material selection.

Valves

Material selection for valves shall be appropriate for the piping class that they are classified within and in accordance with the requirements of ASME B16.34. Further details on valve materials may be found in AGES- SP-09-003, the Piping & Pipeline Valve Specification.

Valves for subsea applications will be selected in accordance with API 6DSS. Valves shall be selected in conformance with ADNOC specification AGES-SP-09-003.

Static Equipment

Material guidelines for pressure vessels are given in Tables 6 and 7 above. This is commonly CS with an internal lining or CRA cladding. The guidelines for selection between CS with cladding versus a solid CRA option are given in Section 11.3 but should be considered on a case-by-case basis. Welds and acceptance requirements shall be as per ASME IX.

Where sour service material selection applies for vessels, refer to Section 11.5. Where outside of the NACE MR0175 / ISO 15156-3 limits for 316 SS, vessels shall be internally cladded/weld overlaid with Alloy 625.

As mentioned in Section 11.6, the design, and therefore material selection, of heat exchangers is dependent on their service requirements. However, in all cases, materials shall follow these guidelines:

The material to be selected to meet the design life requirements of the
The material selection shall be driven by the design
Titanium ASTM B265 Grade 2 is the recommended grade for heat exchanger applications containing seawater and rich glycol. The potential for titanium hydriding shall be considered in the design of all titanium heat exchangers, ensuring conditions do not exceed 80 °C, a pH is either below 3 or above 12 (or above 7 with high H2S content), and there is no mechanism available for generating hydrogen; for example, galvanic coupling.
CA should not generally be available for CS in heat exchangers; therefore, it may require an upgrade in specification to a suitable CRA.
If using CuNi for tubes in a shell and tube design, the minimum and maximum velocities in Table 9 shall be adhered However, these values will change with pipe diameter and shall be designed on a case-by-case basis.

Material Selection Guidelines: Table 9 – Maximum and Minimum Flow Velocities for CuNi Heat Exchanger Tubes

Tube Material	Velocity (m/s)
Tube Material	Maximum	Minimum
90/10 CuNi	2.4	0.9
70/30 CuNi	3.0	1.5

Further detail on design may be found in AGES-SP-06-003, the Shell and Tube Heat Exchanger Specification. Rotating Equipment/Pumps
Selection of pump material class shall be made by the CONTRACTOR on a case-by-case basis for any COMPANY Project using AGES-SP-05-001, the Centrifugal Pumps (API 610) Specification. Below in Table 10, guidelines are given on the selection of material class for pumps per system. Further material details, including when an upgrade to the specification is required for specific operating conditions, may be found in AGES-SP-05-001.

Material Selection Guidelines: Table 10 – Material Classification for Pumps

Service	Material Class
Sour Hydrocarbon	S-5, A-8
Non-corrosive hydrocarbon	S-4
Corrosive Hydrocarbon	A-8
Condensate, non-aerated	S-5
Condensate, aerated	C-6, A-8
Propane, butane, liquefied petroleum gas, ammonia, ethylene, low-temperature services	S-1, A-8
Diesel oil, gasoline, naphtha, kerosene, gas oils, light, medium and heavy lubricating oils, fuel oil, residuum, crude oil, asphalt, synthetic crude bottoms	S-1, S-6, C-6
Xylene, toluene, acetone, benzene, furfural, MEK, cumene	S-1
Oil products containing sulfur compounds	C-6, A-8
Oil products containing a corrosive aqueous phase	A-8
Liquid sulphur	S-1
Liquid Sulphur Dioxide, dry (max. 0.3% weight H2O), with or without hydrocarbons	S-5
Aqueous Sulphur Dioxide, all concentrations	A-8
Sulfolane (Shell proprietary chemical solvent)	S-5
Short residue containing naphthenic acids (acid number above 0.5 mg KOH/g)	C-6, A-8
Sodium carbonate	I-1
Sodium hydroxide, < 20% concentration	S-1
Glycol	Specified by Licensor
DEA, MEA, MDEA, TEA, ADIP, or Sulfinol solutions containing either H2S or CO2 with more than 1% H2S	S-5
DEA, MEA, MDEA, TEA, ADIP, or Sulfinol solutions, fat, containing CO2 with less than 1% H2S or ≥120 °C	A-8
Boiling and processing water	C-6, S-5, S-6
Boiler Feed Water	C-6, S-6
Foul water and reflux drum water	C-6, S-6
Brackish water	A-8, D-2
Seawater	Case by case basis
Sour water	D-1
Freshwater, aerated	C-6
Drain water, slightly acidic, non-aerated	A-8

Instrument Tubing and Fittings

In general, small tubing less than 1’ NO for Instrumentation I chemicals I Lube/seal oil systems shall be made of 904L material if not specified otherwise.
Instrument tubing/ fitting in utility services with no sour service requirements (instrument air, hydraulic fluid, lube oil, seal oil etc.) for onshore facilities, shall be 316L SS.
For process gas medium involving sour service, application of a CRA material (316L/ 6Mo / Inconel 825) for the Instrument tubing shall be selected in conformance to NACE MR0175 / ISO 15156-3 material limits considering chlorides, H2S partial pressure, pH, and design temperature, or in conformance to NACE MR0103/ ISO 17495 for instrument tubing used in refining environment.
Instrument tubing material selection shall also consider the risk of external chloride-induced stress corrosion cracking and the risk of external pitting and crevice corrosion, especially in chloride-bearing environments. Hence Instrument tubing in offshore facilities (irrespective of services) PVC coated (2 mm thick) 316 SS tube should be considered for exposed marine environments on a case-by-case basis. Alternatively, 6Mo austenitic SS are deemed suitable up to 120 °C in marine environments, the use of which shall be decided upon on a case-by-case basis.

Bolting

All bolts and nuts shall be supplied with certification according to EN 10204, Type 3.1, as a minimum, and Type 3.2 for low-temperature service.
Bolting materials shall comply with bolting tables for ferrous metals, unalloyed and alloyed, provided in Appendix 1– Metallic Materials Selected Standards. Bolting suitable for defined temperature ranges may be found in Table 11, below

Material Selection Guidelines: Table 11 – Material Specification for Bolting Temperature Ranges

Temperature Range (°C)	Material Specification		Size Constraints
Temperature Range (°C)	Bolts	Nuts	Size Constraints
-100 to +400	A320 Grade L7	A194 Grade 4/S3 or grade 7/S3	≤ 65
-100 to +400	A320 Grade L43	A194 Grade 7/S3 or A194 grade 4/S3	< 100
-46 to + 400⁴	A193 Grade B7	A194 Grade 2H	All
-29 to + 540⁴	A193 Grade B16¹	A194 Grade 7	All
-196/+ 540	A193 Grade B8M²	A194 Grade M/8MA³	All

Notes:

This grade should not be used for permanently immersed equipment. Grade B16 is intended for high-temperature service, outside the temperature range for Grade B7.
Type 316 bolts and nuts shall not be used at a temperature above 60°C if exposed to a wet saline
Use 8MA with class 1
The lower temperature limits are subject to interpretation and shall be clarified for each

CS and/or low alloy bolting material shall be hot dip galvanized to ASTM A153 or have similar reliable corrosion protection. For LNG service great care must be taken for the possibility of SS being in contact with galvanized items.
For applications, where dissolution of a thick zinc layer may cause loss of bolt pretension, phosphating shall be used. Bolts coated with poly-tetra-fluoro-ethylene (PTFE) for example Takecoat & Xylan or equivalent can be used but where these bolts rely on cathodic protection then they shall only be used provided electrical continuity is verified by measurements. Cadmium-plated bolts shall not be used.
Where external bolts, nuts, and spacers are to be protected by non-metallic coating, they shall be coated with a PTFE coating that passes a 6,000-hour salt spray test carried out in an ISO 17025 accredited third-party laboratory for these tests. Samples shall be taken from the Applicator facility, not from the paint manufacturer.
Bolting for potential non-metallic coating is applicable to:

All external flanged connections (shop and field assembled), including insulated flange bolting where the service temperature is less than 200 °C.
Equipment bolting that requires removal for scheduled maintenance and inspection. Non-metallic coatings on bolting is not applicable for:
All structural bolting;
Fasteners/bolting used in the assembly of various components within a SUPPLIER package or a MANUFACTURER’s standard equipment, miscellaneous standard value assemblies, and instrumentation. The CONTRACTOR shall review SUPPLIER / MANUFACTURER’s standard coatings for their suitability on a case-by-case basis;
Alloy fasteners;
Bonnet bolts and Gland bolts for Valves;
Bolts for blow-off connection of Strainers;
Bolts for MANUFACTURER’s standard piping speciality items (Sight Glasses, Level Gauges, and Silencers).

Bolting materials for sour service shall meet the requirements of Table 12.

Material Selection Guidelines: Table 12 – Bolting Materials for Sour Service

Service Conditions	Materials	Material Specification		Comments
Service Conditions	Materials	Bolts	Nuts	Comments
Medium and High temperature > -29 °C	Alloy steel	ASTM A193, Grade B7M	ASTM A194 Grade 2, 2H, 2HM	Due to the danger of hydrogen embrittlement caused by cathodic protection, controlled hardness bolts & nuts are required hence the ‘M’ grades are also specified.
Low temperature (-100°C to -29 °C)	Alloy steel	ASTM A320, Grades L7M or L43	ASTM A194, Grade 4 or 7
Medium and High down to -50 °C	DSS and SDSS	ASTM A276; ASTM A479	ASTM A194
Medium and high down to -196 °C Low-pressure applications only	Austenitic SS (316)	ASTM A193 B8M Class 1 (Carbide solution treated and hardness controlled 22HRC max)	ASTM A194 Grade 8M, 8MA (Hardness controlled to 22HRC max)
Medium and high down to -196 °C	Super Austenitic SS	(6%Mo 254 SMO) ASTM A276	ASTM A194
Medium and high down to -196 °C	Nickel base alloy	ASTM B164 ASTM B408 (Monel K-500 or Incoloy 625, Inconel 718, Incoloy 925)	Monel K-500 or Incoloy 625, Inconel 718, Incoloy 925

Specifications OF Materials

Materials standards identified on drawings, requisition sheets, or other documents shall be specified fully in accordance with the guidance given in Sections 10, 11, and 12, including all additional requirements applicable to the standard. For materials identified with a Materials and Equipment Standards Code (MESC) number, the additional requirements stated therein shall also be met.
The latest issue of the selected materials standard shall be used. As this latest issue (including amendments) always prevails, the year of issue of the standard need not be shown.

Metal Temperature Limits
The temperature limits shown in Table A.1 show the minimum limits allowed for the average temperature through the cross-section of the construction material during normal operation.
Table A.1 – Minimum Temperature Limits for Piping and Equipment Steels

Temperature (°C)	Item	Material
Up to -29	Piping/ Equipment	CS
-29 to -46	Piping/ Equipment	LTCS
< -46	Piping	Austenitic SS
Up to -60	Pressure Vessel	LTCS (WPQR weldment, HAZ specimen to be impact tested at min design temperature. Acceptance criteria minimum 27J. In addition, LTCS with CTOD and engineering criticality assessment to be carried out.)
< -60	Pressure Vessel	Austenitic SS
-101°C to -196°C	Piping/Equipment	Austenitic SS/Ni steel with impact testing

It should be noted that the indicated temperature limits do not necessarily exclude the application of the materials beyond these limits, especially for non-pressure-retaining parts such as internal parts of columns, baffles of heat exchangers, and supporting structures.
Maximum temperature limits are presented in sections 2, 3, and 4, temperatures shown in brackets, for example (+400), are unusual for the indicated application but are allowable from a materials point of view, if so required.
Special attention should be given to the specification and application of metals for service at low temperatures. For low-temperature applications, refer to the appendices of Specifications ‘Welding, NDE and Prevention of Brittle Fracture of Pressure Vessels and Heat Exchangers’ and ‘Welding, NDE and Prevention of Brittle Fracture of Piping.’
Categories of Metals

The following categories of metals are covered by this specification:

Ferrous metals – unalloyed
Ferrous metals – alloyed
Nonferrous metals

In each category the following products are dealt with:

Plates, sheets and strip;
Tubes and tubing;
Pipe;
Forgings, flanges and fittings;
Castings;
Bars, sections and wire;

Sequence of Materials
The sequence of materials in the column ‘Designation’ in Sections 2, 3, and 4 is generally such that the subsequent number indicates a material with an increase in the content and/or number of the alloying elements.
Chemical Composition
Chemical composition requirements shown in Sections 2, 3, and 4 relate to product analyses. Percentage compositions listed in Sections 2, 3, and 4 are by mass.
Additional Limits on Materials
The following requirements shall be met unless COMPANY approval for deviations is obtained:

No grade 70 carbon steels shall be used, except SA-516 Grade 70 (subject to COMPANY approval for the particular application, the conditions applicable to Grade 65, and the additional conditions a and b listed below), ASTM A350 LF2, where specified, and ASTM A537 Cl.1 for tanks. Any other grade 70 materials or applications require COMPANY approval except for standard carbon steel forgings and castings for example ASTM A105, A216 WCB, A350 LF2, and A352 LCC.
Steelmaker to provide weldability data for SA-516, Grade 70 used on previous successful projects
Heat treatment condition: Normalised, regardless of
The carbon equivalent and maximum carbon content for all carbon steel components in non-sour service shall be in accordance with the following table:

Table A.2 – Maximum Carbon Content and Equivalents for Steel Components

Components	Max. Carbon Content (%)	Max. Carbon Equivalent (%)
Pressure-containing plates, sheets, strips, pipes, wrought fittings	0.23%	0.43%
Non-pressure containing plates, bars, structural shapes, and other components to be welded	0.23%	N/A
Pressure-containing forgings and castings	0.25%	0.43%

Notes:

Various services and materials require supplemental requirements of normalizing and/or These are covered by the equipment and piping specifications, or by reference to Specification DGS-MW-004, ‘Materials and Fabrication Requirements for Carbon Steel Piping and Equipment in Severe Service.’
All 300 series, chemically stabilized stainless steel materials to be used in applications with operating temperatures above 425°C shall be given a stabilization heat treatment at 900°C for 4 hours subsequent to solution heat treatment.
Rubber linings in water boxes of surface condensers and other exchangers shall not be used without COMPANY approval.
300 series stainless steel tubing shall not be used for steam generating or steam superheating
Cast iron shall not be used in seawater
Whenever ‘SS’ or ‘Stainless Steel’ is indicated in specifications or other Project documents without reference to a specific grade it shall mean 316L SS.
Substitution of 9Cr-1Mo-V, grade ‘91’ materials for applications where 9Cr-1Mo, grade ‘9’ has been specified is not permitted.
- All SS pipe and fittings, especially dual certified 316/316L and 321 shall be standardized as seamless up to 6’ NPS (ASTM A312) and welded class 1 for 8’ NPS and above (ASTM A358 Class 1).

How to choose materials, what materials to choose, why to choose this material and other such questions have always troubled us. The Material Selection Guidelines is a comprehensive assistant that can help you correctly and efficiently select pipes, fittings, flanges, valves, fasteners, steel plates, bars, strips, rods, forgings, castings and other materials for your projects. Let’s use the Material Selection Guidelines to select the right materials for you from ferrous and non-ferrous metal materials for your use in oil and gas, petrochemical, chemical processing, marine and offshore engineering, bioengineering, pharmaceutical engineering, clean energy and other fields.

Material Selection Guidelines: Ferrous Metals – Unalloyed

Plates, Sheet and Strip

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Carbon steel sheets of structural quality, galvanized	100	A 446 – A/ G165	For general use	C content 0.23% max.
Carbon steel plates of structural quality	(+350)	A 283 – C	For non-pressure-retaining parts for up to 50 mm thickness	To be killed or semi-killed
Carbon steel plates (killed or semi-killed)	400	A 285 – C	For pressure-retaining parts. For up to 50 mm thickness (Use subject to specific COMPANY approval)	C content 0.23% max.
Carbon steel plates (Si-killed) – low/medium strength	400	A 515 – 60/65	For pressure-retaining parts (Use subject to specific COMPANY approval)	C content 0.23% max.
C-Mn steel plates (Si-killed) – medium/high strength	400	A 515 -70	For tube sheets not welded to shell and/or tubes. For tube sheets to be welded to shell, see 8.4.3.
C-Mn steel plates (killed or semi-killed) – high strength	400	A 299	For pressure-retaining parts and for tube sheets to be welded to tubes	C content 0.23% max. Mn content 1.30% max.
Fine-grained C-Mn steels – low strength	400	A 516 55/60, A 662 – A	For pressure-retaining parts also at low temperatures	C content 0.23% max. Specify V+Ti+Nb<0.15%
Fine-grained C-Mn steels – medium strength	400	A 516 – 65/70	For pressure-retaining parts also at low temperatures	C content 0.23% max. Specify V+Ti+Nb<0.15%
Fine-grained C-Mn steels – low strength (normalized)	400	A 537 – Class 1	For pressure-retaining parts also at low temperatures (Use subject to specific approval)	Specify V+Ti+Nb<0.15%
Fine-grained C-Mn steels – very high strength (Q+T)	400	A 537 – Class 2	For pressure-retaining parts (Use subject to specific approval)	Specify V+Ti+Nb<0.15%
Carbon steel sheet and strip	—	A1011/A1011M	For structural purposes
Steel floor plate	—	A 786	For structural purposes

Tubes and Tubing

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Electric-resistance-welded carbon steel tubes	400	A 214	For unfired heat transfer equipment	To be killed. A non-destructive electric test in accordance with ASTM A450 or equivalent shall be carried out in addition to the hydrostatic test.
Seamless cold-drawn carbon steel tubes	400	A 179	For unfired heat transfer equipment	To be killed. Only for ASME VIII – Div 1 Application.
Electric-resistance-welded carbon steel tubes	400	A 178 – A	For boilers and superheaters tubes up to and including 102 mm external diameter.	A non-destructive electric test in accordance with ASTM A450 or equivalent shall be carried out in addition to the hydrostatic test. To be killed or semi-killed. Elevated temperature properties (Yield strength as per ASME II Part-D).
Electric-resistance-welded carbon steel tubes (Si-killed)	400	A 226	For boilers and superheaters tubes at high working pressures up to and including 102 mm external diameter.	A non-destructive electric test in accordance with ASTM A450 or equivalent shall be carried out in addition to the hydrostatic test. Elevated temperature properties (Yield strength as per ASME II Part-D).
Seamless carbon steel tubes (Si-killed)	400	A 192	For air coolers, boilers, and superheaters at high working pressures.	A non-destructive electric test in accordance with the material specification shall be carried out in addition to the hydrostatic test. Elevated temperature properties (Yield strength as per ASME II Part-D).
Seamless carbon steel tubes (Si-killed)	400	A 334-6 (Seam-less)	For unfired heat transfer equipment operating at low service temperatures.	C content 0.23% max. A non-destructive electric test in accordance with the material specification shall be carried out in addition to the hydrostatic test.
Seamless carbon steel tubes (Si-killed)	400	A 210 Grade A-1	For air coolers, boilers, and superheaters at high working pressures.	C content 0.23% max. For boilers and superheaters elevated temperature properties (Yield strength shall meet the requirements of ASME II Part-D).

Pipe

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Seamless or Arc Welded Carbon steel pipe	400	API 5L-B	For air and water lines only. Galvanized pipe with screwed connections only.	Specify seamless API 5L-B pipe with NPT threaded couplings, galvanized to ASTM A53, para 17. Seamless pipe to be normalized or hot finished. SAW pipe to be normalized or PWHT after welding.
Electric-fusion-welded carbon steel pipe	400	A 672 – C 65 Class 32/22	For inside plot product lines. For sizes larger than NPS 16.	C content 0.23% max.
Seamless carbon steel pipe	400	ASTM A106 grade B	For most inside plot utility lines. Seamless usually not obtainable in sizes larger than NPS 16.	C content 0.23% max. Mn may be increased to 1.30% max. To be killed or semi-killed.
Seamless C-Mn steel pipe (Si-killed)	400	A 106-B	For most inside plot process piping, including hydrocarbon + hydrogen, hydrocarbon + sulfur compounds.	C content 0.23% max. Mn may be increased to 1.30% max.
Seamless fine-grained C-Mn steel pipe (Si-killed)	(+400)	A 333 – Grade 1 or 6	For process lines at low service temperatures. Seamless usually not obtainable in sizes larger than NPS 16.	C content 0.23% max. Mn may be increased to 1.30% max. Specify V+Ti+Nb < 0.15%.
Electric-fusion-welded fine-grained C-Mn steel pipe (Si-killed)	(+400)	A 671 C65 Class 32	For process lines at moderate or low service temperatures with sizes larger than NPS 16.	C content 0.23% max. Mn may be increased to 1.30% max. Specify V+Ti+Nb < 0.15%.
Carbon steel pipe	—	A 53	For structural use only as handrails.

Forgings, Flanges and Fittings

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Carbon steel butt-welding pipe fittings	400	A 234 – WPB or WPBW	For general use. Sizes up to NPS 16 incl. shall be seamless. Sizes greater than NPS 16 may be either seamless or welded.	C content 0.23% max. Mn may be increased to 1.30% max. Normalized or hot finished. Plate material for A 234 WPB-W to meet sour service requirement: C content 0.23% max, Carbon Equivalent 0.43 max.
Carbon steel butt-welding pipe fittings	(+400)	A 420 – WPL6 or WPL6W	For low service temperature. Sizes up to NPS 16 incl. shall be seamless. Sizes greater than NPS 16 may be either seamless or welded.	C content 0.23% max. Mn may be increased to 1.30% max.
Carbon steel forgings	400	A 105	For piping components, including flanges, fittings, valves, and other pressure-retaining parts and also for tube sheets to be welded to shell.	C content 0.23% max. Mn may be increased to 1.20% max. Shall be normalized in wet H2S, amine, caustic and Criticality 1 services. Heat treatment required by ASTM specification based on rating.
Carbon steel forgings	400	A 266 – Class 2	For pressure vessel components and associated pressure-retaining equipment, including tube sheets.	C content 0.25% max.
Carbon-manganese steel forgings	(+400)	A 350 – LF2 Class 1	For piping components, including flanges, fittings, valves, and other pressure-retaining parts at low service temperatures.	C content 0.23% max. Normalized.
Carbon-manganese steel forgings	350	A 765 – Grade II	For pressure vessel components and associated pressure-retaining equipment, including tube sheets, at low service temperatures.	C content 0.23% max.

Castings

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Grey iron castings	300	A 48 – Class 30 or 40	For non-pressure-retaining (internal) parts.
Grey iron castings	650	A 319 – Class II	For non-pressure-retaining (internal) parts at elevated temperatures.
Grey iron castings	350	A 278 – Class 40	For pressure-retaining parts and cooler channels. Cast iron is not to be used in hazardous service or above 10 bar.
Ductile iron castings	400	A 395	For pressure-retaining parts including fittings and valves.	Metallographic examination in accordance with ASTM A395 shall be made in addition to the tensile test.
Steel castings	(+400)	A 216 – WCA, WCB*, or WCC	For pressure-retaining parts.	*C content 0.25% max.
Steel castings	(+400)	A 352 – LCB* or LCC	For pressure-retaining parts at low service temperatures.	*C content 0.25% max.

Bars, Section and Wire

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Carbon steel bars, sections and raised-tread plates of structural quality	350	A 36	For general structural purposes.	C content 0.23% max. For non-welded items, and for items that will not be welded, restriction on C content may be disregarded. To be killed or semi-killed.
Low-carbon steel bars	400	A 576 – 1022 or 1117	For machined parts.	To be killed or semi-killed. Where free-machining quality is required, specify Grade 1117.
Medium-carbon steel bars	400	A 576 – 1035, 1045, 1055, 1137	For machined parts.	To be killed or semi-killed. Where free-machining quality is required, specify Grade 1137.
High-carbon steel bars	230	A 689/A 576 – 1095	For springs.	To be killed or semi-killed.
Music spring quality steel wire	230	A 228	For springs.
Carbon steel bars and sections	(+230)	A 36	For lifting lugs, sliding bars etc.	C content 0.23% max. For non-welded items, and for items that will not be welded, restriction on C content may be disregarded.
Steel welded wire, fabric	—	—
Carbon steel structural tubing	—	A 500	For structural use only.
Steel bars	—	A 615	For concrete reinforcement.

Bolting

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Carbon steel bolts	230	A 307 – B	For structural purposes. Approved free machining quality acceptable.
Carbon steel nuts	230	A 563 – A	For bolts specified under 8.7.1
Medium-carbon steel nuts	450	A 194 – 2H	For bolting specified under 8.7.1
High-strength structural bolts	—	ASTM F3125	For structural purposes.
Heat-treated steel structural bolts	—	A 490	For structural purposes.
Hardened steel washers	—	F 436	For structural purposes.

Plates, Sheets and Strip

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
1 Cr – 0.5 Mo steel plates	600	A387 – 12 Class 2	For high service temperatures and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered.
1.25 Cr – 0.5 Mo steel plates	600	A 387 – 11 Class 2	For high service temperatures and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered. Specify P 0.005% max. Plates to be solution annealed.
2.25 Cr – 1 Mo steel plates	625	A 387 – 22 Class 2	For high service temperatures and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered.
3 Cr – 1 Mo steel plates	625	A 387 – 21 Class 2	For high service temperatures require optimum creep resistance and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered.
5 Cr – 0.5 Mo steel plates	650	A 387 – 5 Class 2	For high service temperatures and/or resistance to sulfur corrosion.	Specify to be normalized and tempered or quenched and tempered. Plates to be solution annealed.
3.5 Ni steel plates	(+400)	A 203 – D	For pressure-retaining parts at low service temperatures.	Specify: C 0.10% max., Si 0.30% max., P 0.002% max., S 0.005% max.
9 Ni steel plates	-200	A 353	For pressure-retaining parts at low service temperatures.	Specify: C 0.10% max., Si 0.30% max., P 0.002% max., S 0.005% max.
13 Cr steel plates, sheets and strip	540	A 240 – Type 410S or 405	For cladding of pressure-retaining parts under certain corrosive conditions. Type 405 shall not be used above 400°C.
18 Cr-8 Ni steel plates, sheets and strip	-200 (+400)	A 240 – Type 304 or 304N	For non-welded, pressure-retaining parts at low service temperatures or to prevent product contamination.	The material shall be capable of passing the Practice E intergranular corrosion test specified in ASTM A262. Plates to be solution annealed.
18 Cr-8 Ni steel plates, sheets and strip	-0.4	A 240 – Type 304L	For pressure-retaining parts under certain corrosive conditions and/or low and moderate service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni steel plates, sheets and strip	(-100) / +600	A 240 – Type 321 or 347	For pressure-retaining parts under certain corrosive conditions and/or high service temperatures.	For optimum resistance to intergranular corrosion when operating temperatures will be >426°C, apply a stabilization heat treatment at 900°C for 4 hours, subsequent to solution heat treatment. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-10 Ni-2 Mo steel plates, sheets and strip	-0.4	A 240 – Type 316 or 316L	For pressure-retaining parts under certain corrosive conditions and/or high service temperatures.	Type 316L shall be used for all welded components. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262. Plates to be solution annealed.
18 Cr-10 Ni-2 Mo stabilized steel plates, sheets and strip	(-200) / +500	A 240 – Type 316Ti or 316Cb	For pressure-retaining parts under certain corrosive conditions and/or high service temperatures.	For optimum resistance to intergranular corrosion, specify a stabilization heat treatment at 900°C for 4 hours, subsequent to solution heat treatment. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-10 Ni-3 Mo steel plates, sheets and strip	(-200) / +500	A 240 – Type 317 or 317L	For pressure-retaining parts under certain corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
25 Cr-20 Ni steel plates, sheets and strip	1000	A 240 – Type 310S	For pressure-retaining parts under certain corrosive conditions and/or extreme service temperatures.
18 Cr-8 Ni steel plates, sheets and strip	700	A 240 – Type 304H	For pressure-retaining parts at extreme service temperatures under certain corrosive conditions.	Specify C 0.06% max. and Mo+Ti+Nb 0.4% max.
22 Cr-5 Ni-Mo-N steel plates, sheets and strip	(-30) / +300	A 240 – S31803	For pressure-retaining parts under certain corrosive conditions.	Specify N 0.15% min. Specify ferric chloride test in accordance with ASTM G 48 Method A. Plates to be solution heat treated and water cooled.
25 Cr-7 Ni-Mo-N steel plates, sheets and strip	(-30) / +300	A 240 – S32750	For pressure-retaining parts under certain corrosive conditions.	Specify ferric chloride test in accordance with ASTM G 48 Method A. Plates to be solution heat treated and water cooled.
20 Cr-18 Ni-6 Mo-Cu-N steel plates, sheets and strip	-0.5	A 240 – S31254	For pressure-retaining parts under certain corrosive conditions.	Plates to be solution heat treated and water cooled.
Carbon steel or low-alloy steel plates with ferritic stainless steel cladding	—	A 263	For high service temperatures and/or certain corrosive conditions.	Specify base metal and cladding.
Carbon steel or low-alloy steel plates with austenitic stainless steel cladding	400	A 264	For high service temperatures and/or certain corrosive conditions. Specify base metal and cladding.
Seamless 25Cr – 5 Ni Mo-N steel tubes for certain corrosive services			To be annealed and water cooled. To be chemically passivated. Specify ferric chloride test in accordance with ASTM G 48 Method.

Tubes and Tubing

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Seamless 1 Cr-0.5 Mo steel tubes	600	A 213 – T12	For boilers, superheaters and unfired heat transfer equipment at high service temperatures and/or requiring resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered. For resistance to hydrogen attack refer API 941.
Seamless 1.25 Cr-0.5 Mo steel tubes	600	A 213 – T11	For boilers, superheaters and unfired heat transfer equipment at high service temperatures and/or requiring resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered. Specify P 0.005% max.
Seamless 2.25 Cr-1 Mo steel tubes	625	A 213 – T22	For boilers, furnaces, super-heaters and unfired heat transfer equipment at high service temperatures requiring optimum creep resistance and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered.
Seamless 5 Cr-0.5 Mo steel tubes	650	A 213 – T5	For high service temperatures and/or resistance to sulfur corrosion, for example furnace tubes.	Specify to be normalized and tempered or quenched and tempered.
Seamless 9 Cr-1 Mo steel tubes	650	A 213 – T9	For high service temperatures and/or resistance to sulfur corrosion, for example furnace tubes.	Specify to be normalized and tempered or quenched and tempered.
Seamless 3.5 Ni steel tubes	(+400)	–	For low service temperatures.	–
Seamless 9 Ni steel tubes	-200	–	For low service temperatures.	–
Seamless 12 Cr steel tubes	540	A 268 – TP 405 or 410	For unfired heat transfer equipment under certain corrosive conditions.	TP 405 not to be used above 400°C. TP 410 shall be specified with C 0.08 max.
Seamless and welded 18 Cr-10 N-2Mo steel tubes	(-200) +500	A 269 – TP 316 or TP 316L or TP 317 or TP 317L	For certain general applications.	For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB. For tubes to be welded, bent, or stress relieved, TP316L or TP 317L shall be used.
Welded 18 Cr-8 Ni steel tubes	-200 (+400)	A 249 – TP 304 or TP 304L	For superheaters and unfired heat transfer equipment to prevent product contamination or for low service temperatures.	Since the tubes are welded without the addition of filler metal, the inside diameter and the wall thickness of the tubes shall be restricted to NPS 4 max. and 5.5 mm max., respectively.
Welded 18 Cr-8 Ni stabilized steel tubes	(-100) +600	A 249 – TP 321 or TP 347	For superheaters and unfired heat transfer equipment under certain corrosive conditions.	Since the tubes are welded without the addition of filler metal, the inside diameter and the wall thickness of the tubes shall be restricted to NPS 4 max. and 5.5 mm max., respectively. A nondestructive electric test in accordance with ASTM A450 shall be carried out in addition to the hydrostatic test. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Welded 18 Cr-10 Ni-2 Mo steel tubes	300	A 249 – TP 316 or TP 316L	For superheaters and unfired heat transfer equipment under certain corrosive conditions.	Since the tubes are welded without the addition of filler metal, the inside diameter and the wall thickness of the tubes shall be restricted to NPS 4 max. and 5.5 mm max., respectively. A nondestructive electric test in accordance with ASTM A450 shall be carried out in addition to the hydrostatic test. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Welded 20 Cr-18 Ni-6 Mo Cu-N steel tubes	(-200) (+400)	A 249 – S31254	For superheaters and unfired heat transfer equipment under certain corrosive conditions.	Since the tubes are welded without the addition of filler metal, the inside diameter and the wall thickness of the tubes shall be restricted to NPS 4 max. and 5.5 mm max., respectively. A nondestructive electric test in accordance with ASTM A450 shall be carried out in addition to the hydrostatic test.
Seamless 18 Cr-8 Ni steel tubes	200	A 213 – TP 304 or TP 304L	For unfired heat transfer equipment to prevent product contamination or for low service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Seamless 18 Cr-8 Ni stabilized steel tubes	(-100) +600	A 213 – TP 321, TP 347	For superheaters and unfired heat transfer equipment under certain corrosive conditions and/or at high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262. For optimum resistance to intergranular corrosion, specify a stabilization heat treatment subsequent to solution heat treatment.
Seamless 18 Cr-8 Ni steel tubes	815	A 213 – TP 304H	For boilers, superheaters, and unfired heat transfer equipment at extreme service temperatures under certain corrosive conditions.	Specify C 0.06% max. and Mo+Ti+Nb 0.4% max.
Seamless 18 Cr-8 Ni stabilized steel tubes	815	A 213 – TP 321H or TP 347H	For boilers, superheaters, and unfired heat transfer equipment at extreme service temperatures under certain corrosive conditions.	Specify C 0.06% max. and Mo+Ti+Nb 0.4% max.
Seamless 18 Cr-10 Ni-2 Mo steel tubes	300	A 213 – TP 316 or TP 316L	For superheaters and unfired heat transfer equipment under certain corrosive conditions and/or at high service temperatures.	TP 316 shall be used only for non-welded items. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Seamless 18 Cr-8 Ni steel tubes	815	A 271 – TP 321H or TP 347H	For furnaces under certain corrosive conditions with a maximum wall thickness of 25mm.	–
Seamless 25 Cr-5 Ni-Mo steel tubes	300	A 789 – S31803	For certain corrosive conditions.	Specify seamless.
Seamless 25 Cr-7 Ni-Mo-N steel tubes	300	A 789 – S32750	For certain corrosive conditions.	Specify seamless.
Seamless 20 Cr-18 Ni-6 Mo-Cu-N steel tubes	(-200) (+400)	A 269 – S31254	For certain corrosive conditions.	Specify seamless.
Seamless 25 Cr-5 Ni Mo-N steel tubes	300	A 789 – S32550	For certain corrosive services.	Specify seamless.

Pipe

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Electric-fusion-welded 1 Cr-0.5 Mo steel pipe in sizes NPS 16 and larger	600	A 691 1Cr Class 22 or 42	For high service temperatures, requiring optimum creep resistance and/or resistance to hydrogen attack	For Class 22, base material to be in N & T or Q&T condition, with tempering at 730°C min. Welds to be PWHT in range 680-780°C. For Class 42, tempering temperature to be 680°C min. Specify P 0.01% max
Electric-fusion-welded 1.25 Cr-0.5 Mo steel pipe in sizes NPS 16 and larger	600	A 691 – 1.25Cr Class 22 or 42	For high service temperatures, requiring optimum creep resistance and/or resistance to hydrogen attack	For Class 22, base material to be in N & T or Q&T condition, with tempering at 730°C min. Welds to be PWHT in range 680-780°C. For Class 42, tempering temperature to be 680°C min. Specify P 0.01% max.
Electric-fusion-welded 2.25 Cr steel pipe in sizes NPS 16 and larger	625	A 691 – 2.25 Cr Class 22 or 42	For high service temperatures, requiring optimum creep resistance and/or resistance to hydrogen attack	For Class 22, base material to be in N & T or Q&T condition, with tempering at 730°C min. Welds to be PWHT in range 680-780°C. For Class 42, tempering temperature to be 680°C min. Specify P 0.01% max.
Electric-fusion-welded 5 Cr-0.5 Mo steel pipe in sizes NPS 16 and larger	650	A 691 – 5 Cr Class 22 or 42	For high service temperatures and/or resistance to sulfur corrosion	For Class 22, base material to be in N & T or Q&T condition, with tempering at 730°C min. Welds to be PWHT in range 680-780°C. For Class 42, tempering temperature to be 680°C min. Specify P 0.01% max.
Electric-fusion-welded 18 Cr-8 Ni steel pipe in sizes above NPS 12	-200 to +400	A 358 – Grade 304 or 304L Class 1	For certain corrosive conditions and/or high service temperatures	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Electric-fusion-welded 18 Cr-8 Ni stabilized steel pipe in sizes above NPS 12	-100 to +600	A 358 – Grade 321 or 347 Class 1	For certain corrosive conditions and/or high service temperatures	For optimum resistance to intergranular corrosion, specify a stabilization heat treatment at 900°C for 4 hours after solution heat treatment, as detailed in ASTM A358. Supplementary Requirement S6. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Electric-fusion-welded 18 Cr-10 Ni-2 Mo steel pipe in sizes above NPS 12	-200 to +500	A 358 – Grade 316 or 316L Class 1	For certain corrosive conditions and/or high service temperatures	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Electric-fusion-welded 18 Cr-8 Ni steel pipe in sizes above NPS 12	-200 to +500	A 358 – Grade 304L Class 1	For certain corrosive conditions and/or high service temperatures	Specify C 0.06% max and Mo+Ti+Nb 0.04% max.
Seamless 0.3 Mo steel pipe	500		NOT for hydrogen service. For high service temperatures	Specify total Al content 0.012% max.
Seamless 0.5 Mo steel pipe	500	A 335 – P1	NOT for hydrogen service. For high service temperatures	Specify total Al content 0.012% max.
Seamless 1 Cr-0.5 Mo steel pipe	500	A 335 – P12	For high service temperatures and/or resistance to hydrogen attack	Specify to be normalized and tempered. For resistance to hydrogen attack refer API 941. Purchaser to advise the manufacturer if the service temperature is to be over 600°C
Seamless 1.25 Cr-0.5 Mo steel pipe	600	A 335 – P11	For high service temperatures and/or resistance to hydrogen attack Seamless is usually not obtainable in sizes larger than NPS 16. For larger sizes use ASTM A691 – 1.25 CR-Class 22 or 42 (9.3.2).	Specify to be normalized and tempered. Specify P 0.005% max. For resistance to hydrogen attack refer API 941 Purchaser to advise the manufacturer if the service temperature is to be over 600°C
Seamless 2.25 Cr-1 Mo steel pipe	625	A 335 – P22	For high service temperatures, requiring optimum creep resistance and/or resistance to hydrogen attack Seamless is usually not obtainable in sizes larger than NPS 16. For larger sizes use ASTM A691 – 2.25 Cr-Class 22 or 42 (see 9.3.3).	Specify to be normalized and tempered. For resistance to hydrogen attack refer API 941. Purchaser to advise the manufacturer if the service temperature is to be over 600°C
Seamless 5 Cr-0.5 Mo steel pipe	650	A 335 – P5	For high service temperatures and/or resistance to sulfur corrosion Seamless is usually not obtainable in sizes larger than NPS 16. For larger sizes use ASTM A691 – 5 Cr-Class 22 or 42 (see 9.3.4).	Specify to be normalized and tempered or quenched and tempered.
Seamless 9 Cr-1 Mo steel pipe	650	A 335 – P9	For high service temperatures and/or resistance to sulfur corrosion	Specify to be normalized and tempered. Purchaser to advise the manufacturer if the service temperature is to be over 600°C
Seamless 3.5 Ni steel pipe	400	A 333 – Grade 3 Seamless	For low service temperatures
Seamless 9 Ni steel pipe	-200	A 333 – Grade 8 Seamless	For low service temperatures	Specify: C 0.10% max. S 0.002% max. P 0.005% max.
Seamless and welded 18 Cr-8 Ni steel pipe in sizes to NPS 12 incl.	-200 to +400	A 312 – TP 304	For low service temperatures or to prevent product contamination	Welded pipe may be used up to and including 5.5 mm wall thickness. The materials shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A 262
Seamless and welded 18 Cr-8 Ni steel pipe in sizes to NPS 12 incl.	-200 to +400	A 312 – TP 304L	For certain corrosive conditions and/or high service temperatures	Welded pipe may be used up to and including 5.5 mm wall thickness. The materials shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A 262
Seamless and welded 18 Cr-8 Ni stabilized steel pipe in sizes to NPS 12 incl.	-100 to +600	A 312 – TP 321 or TP 347	For certain corrosive conditions and/or high service temperatures	Welded pipe may be used up to and including 5.5 mm wall thickness. For optimum resistance to intergranular corrosion, specify a stabilization heat treatment at 900°C for 4 hours subsequent to solution heat treatment, as detailed in ASTM A358 Supplementary Requirement S5 The materials shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A 262
Seamless and welded 18 Cr-8 Ni stabilized steel pipe in sizes to NPS 12 incl.	815	A 312 – TP 321H or TP 347H	For certain corrosive conditions and/or extreme service temperatures	Welded pipe may be used up to and including 5.5 mm wall thickness.
	815	A 312 – TP 321H or TP 347H		The use of this grade is subject to the agreement of the Company.
Seamless and welded 18 Cr-10 Ni-2 Mo steel pipe in sizes to NPS 12 incl.	-200 to +500	A 312 – TP 316 or TP 316L	For certain corrosive conditions and/or high service temperatures	Welded pipe may be used up to and including 5.5 mm wall thickness.
	-200 to +500	A 312 – TP 316 or TP 316L		The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
Seamless and welded 18 Cr-8 Ni steel pipe in sizes to NPS 12 incl.	+500 (+815)	A 312 – TP 304H	For certain corrosive conditions and/or high service temperatures	Specify C 0.06% max. and Mo+Ti+Nb 0.4% max.
Seamless and welded 22 Cr-5 Ni- Mo-N steel pipe	300	A 790 – S 31803	For certain corrosive conditions	Specify N 0.15% min.
				Welded pipe may be used up to and including 5.5 mm wall thickness.
				Specify in solution annealed and water-quenched condition.
Seamless and welded 25 Cr-7 Ni-Mo-N steel pipe	300	A 790 – S 32750	For certain corrosive conditions	Specify N 0.15% min.
				Welded pipe may be used up to and including 5.5 mm wall thickness.
				Specify in solution annealed and water-quenched condition.
Seamless and welded 20 Cr-18 Ni-6 Mo-Cu-N steel pipe	-200 (+400)	A 312 – S31254	For certain corrosive conditions	Welded pipe may be used up to and including 5.5 mm wall thickness.

Forgings, Flanges and Fittings

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
0.5 Mo steel butt-welding fittings	500	A 234 – WP1 or WP1W	NOT for hydrogen service.For high service temperatures.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify total Al content 0.012% max.
1 Cr-0.5 Mo steel butt-welding fittings	600	A 234 – WP12 Class 2 or WP12W Class 2	For high service temperatures and/or resistance to hydrogen attack.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify to be normalized and tempered or quenched and tempered. Specify P 0.005% max. For resistance to hydrogen attack refer API 941.
1.25Cr-0.5Mo steel butt-welding fittings	600	A 234 – WP11 Class 2 or WP11W Class 2	For high service temperatures and/or resistance to hydrogen attack.	Sizes up to NPS 16 incl. shall be seamless. Specify P 0.005% max. For well metal, specify 10P+55Pb+5Sn+As (1400 ppm).
2.25 Cr-1 Mo steel butt-welding fittings	625	A 234 – WP22 Class 3 or WP22W Class 3	For extreme service temperatures and/or resistance to sulfur corrosion.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify to be normalized and tempered or quenched and tempered. For resistance to hydrogen attack refer API 941.
5 Cr-0.5 Mo steel butt-welding fittings	650	A 234 – WP5 or WP5W	For high service temperatures and/or resistance to sulfur corrosion.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify to be normalized and tempered or quenched and tempered.
3.5 Ni steel butt-welding fittings	(+400)	A 420 – WPL3 or WPL3W	For low service temperatures.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify to be normalized.
9 Ni steel butt-welding fittings	-200	A 420 – WPL8 or WPL8W	For low service temperatures.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify to be double normalized or quenched and tempered. Specify C 0.10% max., S 0.002% max., P 0.005% max.
18 Cr-8 Ni steel butt-welding fittings	-200 to +400	A 403 – WP304-S/WX/WU	For low service temperatures or to prevent product contamination.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Material must pass the Practice E intergranular corrosion test as specified in ASTM A262. Test all seam welds of austenitic stainless steel.
18 Cr-8 Ni steel butt-welding fittings	-200 to +400	A 403 – WP304L-S/WX/WU	For certain corrosive conditions and/or high service temperatures.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni steel butt-welding fittings	815	A 403 – WP304H-S/WX/WU	For certain corrosive conditions and/or extreme service temperatures.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify: C 0.06% max and Mo+Ti+Nb 0.4% max.
18 Cr-8 Ni stabilized steel butt-welding fittings	(-100) to +600	A 403 – WP321-S/WX/WU or WP347-S/WX/WU	For certain corrosive conditions and/or extreme service temperatures.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. For optimum resistance to intergranular corrosion, specify a stabilization heat treatment at 900°C for 4 hours subject to a solution heat treatment.
18 Cr-8 Ni stabilized steel butt-welding fittings	815	A 403 – WP321H-S/WX/WU or WP347H-S/WX/WU	For certain corrosive conditions and/or extreme service temperatures.	The use of this grade is subject to agreement of the Company.
18 Cr-10 Ni-2 Mo steel butt-welding fittings	-200 to +500	A 403 – WP316-S/WX/WU or WP316L-S/WX/WU	For certain corrosive conditions and/or high service conditions.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
22 Cr-5 Ni-Mo-N steel butt-welding fittings	300	A815 – S31803 Class WP-S or WP-WX	For certain corrosive conditions.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded. Specify N 0.15% min.
25 Cr-7 Ni-Mo-N steel butt-welding fittings for corrosive conditions	300	A815 – S32750 Class WP-S or WP-WX	For corrosive conditions.	Specify Seamless.
20 Cr-18 Ni-6 Mo-Cu-N steel butt-welding fittings	(-200) to +400	A403 – WPS 31254-S/WX/WU	For certain corrosive conditions.	Sizes up to NPS 16 incl. shall be seamless. Larger sizes may be either seamless or welded.
0.5 Mo steel forgings	500	A 182 -F1	NOT for hydrogen service. For tube sheets, flanges, fittings, valves and other pressure-retaining parts at high service temperatures
0.5 Mo steel forgings	+500	A 336 – F1	For heavy parts, e.g., drum forgings, for high service temperatures. NOT for hydrogen service.	Specify total Al content 0.012% max.
1 Cr-0.5 Mo steel forgings	+600	A 182 – F12 Class 2	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at high service temperatures. Resistant to hydrogen attack.	Specify to be normalized and tempered. For resistance to hydrogen attack, refer to API 941.
1 Cr-0.5 Mo steel forgings	+600	A 336 – F12	For heavy parts, e.g., drum forgings, for high service temperatures and/or resistance to hydrogen attack.	Specify to be normalized and tempered. For resistance to hydrogen attack, refer to API 941.
1.25 Cr-0.5 Mo steel forgings	+600	A 182 – F11	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at high service temperatures. Resistant to hydrogen attack.	Specify to be normalized and tempered. Specify P 0.005% max. For resistance to hydrogen attack, refer to API 941.
1.25 Cr-0.5 Mo steel forgings	+600	A 336 – F11	For heavy parts, e.g., drum forgings, for high service temperatures and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered. Use of liquid quenched and tempered grades is subject to agreement. Specify P 0.005% max.
2.25 Cr-1 Mo steel forgings	+625	A 182 – F22	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at high service temperatures. Resistant to hydrogen attack.	Specify to be normalized and tempered. Refer to API 934 for Materials and Fabrication requirements.
2.25 Cr-1 Mo steel forgings	+625	A 336 – F22	For heavy parts, e.g., drum forgings, for high service temperatures and/or resistance to hydrogen attack.	Specify to be normalized and tempered or quenched and tempered. Use of liquid quenched and tempered grades is subject to agreement. Refer to API 934.
3 Cr-1 Mo steel forgings	+625	A 182 – F21	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at high service temperatures. Resistant to hydrogen attack.	Specify to be normalized and tempered. Refer to API 934 for Materials and Fabrication requirements.
5 Cr-0.5 Mo steel forgings	+650	A 182 – F5	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at high service temperatures. Resistant to sulfur corrosion.	Specify to be normalized and tempered.
3.5 Ni steel forgings	(-400)	A 350 – LF3	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at low service temperatures.	Specify: C 0.10% max, Si 0.30% max, Mn 0.90% max, S 0.005% max.
9 Ni steel forgings	(-200)	A 522 – Type I	For tube sheets, flanges, fittings, valves, and pressure-retaining parts at low service temperatures.	Specify: C 0.10% max, Si 0.30% max, Mn 0.90% max, S 0.005% max.
12 Cr steel forgings	+540	A 182 F6a	For certain corrosive conditions.
12 Cr steel forgings	+540	A 182 – F6a	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni steel forgings	-200 / +400	A 182 – F304	For low service temperatures or to prevent product contamination.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni steel forgings	-200 / +400	A 182 – F304L	For certain corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni steel forgings	-200 / +500	A 182 – F304L	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni steel forgings	+815	A 182 – F304H	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under extreme service temperatures.	Specify C 0.06% max. Mo+Ti+Nb 0.4% max.
18 Cr-8 Ni stabilized steel forgings	+600	A 182 – F321 / F347	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under corrosive conditions and/or high service temperatures.	For optimum resistance to intergranular corrosion, specify a stabilization heat treatment of 870-900°C for 4 hours, followed by solution heat treatment. The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-8 Ni stabilized steel forgings	+815	A 182 – F321H / F347H	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under extreme service temperatures.	The use of this grade is subject to the agreement of the Company.
18 Cr-10 Ni-2 Mo steel forgings	-200 / +500	A 182 – F316	For certain corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-10 Ni-2 Mo steel forgings	-200 / +500	A 182 – F316L	For certain corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
18 Cr-10 Ni-2 Mo steel forgings	-200 / +500	A 182 – F316H	For certain corrosive conditions and/or high service temperatures.	The material shall be capable of passing the Practice E intergranular corrosion test as specified in ASTM A262.
22 Cr-5 Ni-Mo-N steel forgings	-30 / +300	A 182 – F51	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under corrosive conditions.	Specify N 0.15% min.
25 Cr-7 Ni-Mo-N steel forgings	(-30) to +300	A 182 – F53	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under certain corrosive conditions.	–
20 Cr-18 Ni-6 Mo-Cu-N steel forgings	(-200) to (+400)	A 182 – F44	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts under certain corrosive conditions.	–
9Cr Mo Steel forgings	+650	ASTM A182-F9	For tube sheets, flanges, fittings, valves, and other pressure-retaining parts at extreme service temperatures and/or requiring resistance to Sulphur corrosion.	Normalized and tempered
Wrought Ni-Cr-Mo-Nb alloy (Alloy 625) for corrosive conditions	425	ASTM B366	Chemically passivated and free from any scale or oxides. Specify in the solution annealed condition.	–
Ni-Cr-Fe Alloy (Alloy 600) forgings for corrosive conditions	+650	ASTM B564 N06600	Specify forgings in solution annealed condition.	–

Castings

Designation	Metal Temp (°C)	ASTM Specification	Remarks	Added Requirements
14.5 Si castings	+250	A 518 – 1	For non-pressure-retaining (internal) parts.	Specify Si content 14.5% min. Other alloying elements for a given Mo.
18-16-6 Cu-2 Cr-Nb (Type 1) castings	+500	A 436 – Type 1	For non-pressure-retaining (internal) parts under certain corrosive conditions.	–
18-20 Cr-2 Ni-Nb-Ti (Type D-2) castings	+500	A 439 – Type D-2	For pressure-retaining parts under certain corrosive conditions.	–
22 Ni-4 Mn castings	+500	A 571 – Type D2-M	For pressure-retaining parts at low service temperatures.	–
0.5 Mo steel castings	+500	A 217 – WC1	Not for hydrogen service. For fittings, valves, and other pressure-retaining parts at high service temperatures and/or resistance to hydrogen attack.	Specify total Al content 0.012% max.
1.25 Cr-0.5 Mo steel castings	+550	A 217 – WC6	For fittings, valves, and other pressure-retaining parts at high service temperatures and/or requiring resistance to sulfur corrosion.	Specify 0.01% max. Al. Normalized and tempered.
2.25 Cr-1 Mo steel castings	+650	A 217 – WC9	For fittings, valves, and other pressure-retaining parts at high service temperatures and/or resistance to hydrogen attack.	Specify 0.01% max. Resistance to hydrogen attack per API 941.
5 Cr-0.5 Mo steel castings	+650	A 217 – C5	For fittings, valves, and other pressure-retaining parts at high service temperatures and/or resistance to sulfur corrosion.	–
9 Cr-1 Mo steel castings	+650	A 217 – C12	For fittings, valves, and other pressure-retaining parts at high service temperatures and/or resistance to sulfur corrosion.	–
3.5 Ni steel castings	(+400)	A 352 – LC3	For low service temperatures.	–
9 Ni steel castings	(+400)	A 352 – LC9	For low service temperatures.	Specify: C 0.10% max, S 0.002% max, P 0.005% max.
12 Cr steel castings	+540	A 743 – CA15	For non-pressure-retaining parts under corrosive conditions.	–
12 Cr-4 Ni steel castings	+540	A 217 – CA15	For pressure-retaining parts under certain corrosive conditions.	–
18 Cr-8 Ni steel castings	+200	A 744 – CFB	For non-pressure-retaining (internal) parts under certain corrosive conditions and/or at high service temperatures.	Castings for corrosive service shall be capable of meeting the requirements of ASTM A262, Practice E.
18 Cr-10 Ni-Nb (stabilized) steel castings	+1000	A 744 – CFBC	If intended for hydrogen service, specify 0.012% max Al content for resistance to hydrogen attack. Castings for corrosive service shall be capable of meeting the requirements of ASTM A262, Practice E.
18 Cr-10 Ni-2 Mo steel castings	+500	A 744 – CBFM	For non-pressure-retaining (internal) parts under certain corrosive conditions and/or at high service temperatures.	Castings for corrosive service shall be capable of meeting the requirements of ASTM A262, Practice E.
25 Cr-20 Ni steel castings	+1000	A 297 – HK	For non-pressure-retaining (internal) parts requiring heat resistance.	–
25 Cr-12 Ni steel castings	+1000	A447-Type II	For furnace tube supports.
18 Cr-8 Ni steel castings	-200 to +500	A351-CF8	For pressure-retaining parts under certain corrosive conditions and/or at high service temperatures.	Castings for corrosive service shall be capable of meeting the requirements of ASTM A262, Practice E.
18 Cr-8 Ni-Nb stabilized steel castings	(-100) to +600	A351-CF8C	For pressure-retaining parts under certain corrosive conditions and/or at high service temperatures.	If intended for working temperatures above 500°C, specific Si content 1.0% max. Castings for corrosive service shall be capable of meeting the requirements of ASTM A262, Practice E.
18 Cr-10 Ni-2 Mo steel castings	-200 to +500	A351-CF8M	For pressure-retaining parts under certain corrosive conditions and/or at high service temperatures.	Castings for corrosive service shall be capable of meeting the requirements of ASTM A262, Practice E.
22 Cr-5 Ni-Mo-N steel castings	+300	A890-4A, S32 & S33	For pressure-retaining parts under certain corrosive conditions.
25 Cr-7 Ni-Mo-N steel castings	+300	A890-5A, S32 & S33	For pressure-retaining parts under certain corrosive conditions.
20 Cr-18 Ni-6 Mo-Cu-N steel castings	(-200) to (+400)	A351-CK3MCuN	For pressure-retaining parts under certain corrosive conditions.
25 Cr-20 Ni steel castings	+1000	A351-CH20	For pressure-retaining parts under certain corrosive conditions at extreme service temperatures.
25 Cr-20 Ni steel castings	+1000	A351-CK20	For pressure-retaining parts under certain corrosive conditions at extreme service temperatures.
25 Cr-20 Ni steel castings	+1000	A351-HK40	For pressure-retaining parts under certain corrosive conditions at extreme service temperatures.
20 Cr-29 Ni-Mo-Cu steel castings	(+400)	A744-CN7M	For fittings, valves, and other pressure-retaining parts requiring resistance to sulfuric acid corrosion.
Cr-Ni steel centrifugal and static castings 20 Cr-33 Ni-Nb 25 Cr-30 Ni 25 Cr-35 Ni-Nb			For pressure-retaining furnace parts at extreme service temperatures.

Bars, Sections and Wire

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
1 Cr-0.25 Mo steel bars	+450 (+540)	A 322 – 4140	For machined parts
9 Ni steel bars	-200	A 322	For machined parts, for low-temperature service
12 Cr steel bars	+425	A 276 – Type 410 or Type 420	Free-machining quality ASTM A582, Type 416 or 416Se acceptable, subject to approval by the Company	For welded items specify Type 405
18 Cr-8 Ni steel bars	-200 to +500	A 479 – Type 304	For machined parts	The material shall be capable of meeting the requirements of ASTM A262 Practice E
18 Cr-8 Ni steel bars	-200 to +500	A 479 – Type 304L	For machined parts	The material shall be capable of meeting the requirements of ASTM A262 Practice E
18 Cr-8 Ni steel bars	+500 (+815)	A 479 – Type 304H	For machined parts	Specify C: 0.06% max., Mo+Ti+Nb: 0.4% max.
18 Cr-8 Ni stabilized steel bars	-200 (+815)	A 479 – Type 321 or Type 347	For machined parts	The material shall be capable of meeting the requirements of ASTM A262 Practice E
18 Cr-8 Ni stabilized steel bars	+500 (+815)	A 479 – Type 321H or Type 347H	For machined parts, the use of this grade is subject to the agreement of the Company
18 Cr-10 Ni-2 Mo steel bars	-200 to +500	A 479 – Type 316	For machined parts	The material shall be capable of meeting the requirements of ASTM A262 Practice E
18 Cr-10 Ni-2 Mo steel bars	-200 to +500	A 479 – Type 316L	For machined parts	The material shall be capable of meeting the requirements of ASTM A262 Practice E
22 Cr-5 Ni-Mo-N steel bars	-30 to +300	A 479 – S31803	For machined parts	N 0.15% min.
25 Cr-7 Ni-Mo-N steel bars	-30 to +300	A 479 – S32750	For machined parts	N 0.15% min.
20 Cr-18 Ni-6 Mo-Cu-N steel bars	-200 (+400)	A 276 – S31254	For machined parts
Si-Mn steel bars	+230	A 689/A 322-9260	For springs
Cold-drawn steel wire	+230	A 227	For springs
Cold-drawn 18 Cr-8Ni steel wire	+230	Type 302	For springs	The material shall be capable of meeting the requirements of ASTM A262 Practice E

Bolting

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
1 Cr-0.25 Mo steel bolting material	+450 (+540)	A 193 – B7	For general use. For nuts see 8.7.3.	–
1 Cr-0.25 Mo steel bolting material	+450 (+540)	A 193 – B7M	For sour service. For nuts see 9.7.13.	–
1 Cr-0.5 Mo-0.25 steel bolting material	+525 (+600)	A 193 – B16	For high-temperature service. For nuts see 9.7.14.	–
1 Cr-0.25 Mo steel bolting material	-105 to +450 (+540)	A 320 – L7	For low-temperature service. For nuts see 9.7.15.	–
1 Cr-0.25 Mo steel bolting material	-30 to +450	A 320 – L7M	For sour service and low-temperature service. For nuts see 9.7.16.	–
9 Ni steel bolting material	-200	–	For low-temperature service. For nuts see 9.7.17.	–
12 Cr steel bolting material	+425 (+540)	A 193 – B6X	For certain corrosive conditions. For nuts see 9.7.18.	–
18 Cr-8 Ni steel (strain-hardened) bolting material	-200 to +815	A 193 – B8 Class 2	For certain corrosive conditions and/or extreme-temperature service. For nuts see 9.7.19.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
18 Cr-8 Ni stabilized steel bolting material	-200 to +815	A 193 – B8T or B8C	For certain corrosive conditions and/or extreme-temperature service. For nuts see 9.7.21.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
18 Cr-10 Ni-2 Mo steel (strain hardened) bolting material	-200 to +500	A 193 – BBM Class 2	For certain corrosive conditions and/or high-temperature service. For nuts see 9.7.22.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
18 Cr-8 Ni steel bolting material	-200	A 193 – BBN	For low-temperature service. For nuts see 9.7.20.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
Precipitation Hardening austenitic Ni-Cr steel bolting material	+540	A 453-660 Class A	For certain corrosive conditions and/or high-temperature service. Expansion coefficient is comparable with austenitic steels. For nuts see 9.7.23.	–
0.25 Mo steel nuts	+525	A 194 – 2HM	For bolting made from material specified under 9.7.2.	–
0.25 Mo steel nuts	+525 (+600)	A 194 – 4	For bolting made from material specified under 9.7.3	–
0.25 Mo steel nuts	-105 to +525 (+540)	A 194 – 4, S4	For bolting made from material specified under 9.7.4	–
0.25 Mo steel nuts	+525	A 194 – 7M, S4	For bolting made from material specified under 9.7.5	–
9 Ni steel nuts	-200	–	For bolting made from material specified under 9.7.6	–
12 Cr steel nuts	+425 (+540)	A 194 – 6	For bolting made from material specified under 9.7.7. Free-machining Grade 6F acceptable, subject to approval of the Company.	–
18 Cr-8 Ni steel (strain hardened) nuts	-200 to +815	A 194 – 8, S1	For bolting made from material specified under 9.7.8. Free-machining Grade 8F acceptable, subject to approval of the Company.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
18 Cr-8 Ni steel nuts	-200	A 194 – 8N	For low-temperature service.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
18 Cr-8 Ni stabilized steel nuts	-200 to +815	A 194 – 8T or 8C	For bolting made from material specified under 9.7.9. Free-machining Grade 8F acceptable, subject to approval of the Company.	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
18 Cr-10 Ni-2 Mo steel (strain hardened) nuts	-200 to +500	A 194 – 8M, S1	For bolting made from material specified under 9.7.10	The material shall be capable of meeting the requirements of ASTM A262 Practice E.
Precipitation hardening austenitic Ni-Cr steel nuts	+540	A 453-660 Class A	For bolting made from material specified under 9.7.12	–
0.75 Cr-1.75 Ni, 0.25 Mo steel bolting material for low-temperature services	+400	A320-L43	–	–

Material Selection Guidelines: Nonferrous Metals

Plates, Sheets and Strip

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Aluminum plates and sheets	-200 to +200	B 209 – Alloy 1060	For certain corrosive conditions	Specify annealed condition for all grades.
Al-2.5Mg alloy plates and sheets	-200 to +200	B 209 – Alloy 5052	For general use under certain corrosive conditions	Specify annealed condition for all grades.
Al-2.7Mg-Mn alloy plates and sheets	-200 to +200	B 209 – Alloy 5454	For general use under certain corrosive conditions	Specify annealed condition for all grades.
Al-4.5Mg-Mn alloy plates and sheets	-200 to +65	B 209 – Alloy 5083	For low temperature applications	Specify annealed condition for all grades.
Copper plates, sheets, and strip	-200 to +150	B 152 – C12200	For certain corrosive conditions	Specify annealed condition for all grades.
Cu-Zn alloy plates and sheets	-200 to +175	B 171 – C46400	For baffles of coolers and condensers in brackish and seawater service and for general use under certain corrosive conditions	Specify annealed condition for all grades.
Cu-Al alloy plates and sheets	-200 to +250	B 171 – C61400	For tube sheets of coolers and condensers in sweet and brackish water service and for general use under certain corrosive conditions	Specify annealed condition for all grades.
Cu-Al alloy plates and sheets	-200 to +350	B 171 – C63000	For tube sheets of coolers and condensers in brackish and seawater service and for general use under certain corrosive conditions. Tube sheets produced by special casting methods from approved manufacturers are acceptable, provided mechanical properties and chemical composition are compatible with this specification.	Al content max. 10.0%.
Cu-Ni (90/10) alloy plates and sheets	-200 to +350	B 171 – C70600	For tube sheets of coolers and condensers in brackish and seawater service and for general use under certain corrosive conditions	–
Cu-Ni (70/30) alloy plates and sheets	-200 to +350	B 171 – C71500	For certain corrosive conditions	–
Nickel plates, sheets, and strip	-200 to (+350)	B 162 – N02200	For certain corrosive conditions	Specify annealed condition for all grades.
Low-carbon nickel plates, sheets, and strip	-200 to (+350)	B 162 – N02201	For certain corrosive conditions	Specify annealed condition for all grades.
Ni-Cu alloy	-200	B 127 –	For certain corrosive conditions	Specify annealed condition for all grades.
Monel (400) plates, sheets, and strip	+400	N04400	For certain corrosive conditions	Specify annealed condition for all grades.
Ni-Cr-Fe alloy (Inconel 600) plates, sheets and strip	+650	B 168 – N06600	For high-temp. conditions and/or certain corrosive conditions	Specify annealed condition for all grades
Ni-Fe-Cr alloy (Incoloy 800) plates, sheets and strip	+815	B 409 – N08800	For high-temp. conditions and/or certain corrosive conditions	Specify C 0.05% maximum; specify the annealed condition for all grades
Ni-Fe-Cr alloy (Incoloy 800H) plates, sheets and strip	+1000	B 409 – N08810	For high-temp. conditions and/or certain corrosive conditions	Specify annealed condition for all grades
Ni-Fe-Cr alloy (Incoloy 800HT) plates, sheets and strip	(+1000)	B 409 – N08811	For high-temp. conditions and/or certain corrosive conditions	Specify annealed condition for all grades
Ni-Fe-Cr-Mo-Cu alloy (Incoloy 825) plates, sheets and strip	+425	B 424 – N08825	For certain corrosive conditions	The material must pass Practice C intergranular corrosion test as per ASTM A262 (corrosion rate ≤ 0.3 mm/year)
Ni-Cr-Mo-Nb alloy (Inconel 625) plates, sheets and strip	+425	B 443 – N06625	For certain corrosive conditions	N/A
Ni-Mo alloy (Hastelloy B2) plates, sheets and strip	+425	B 333 – N10665	For certain corrosive conditions	N/A
Ni-Mo-Cr alloy (Hastelloy C4) plates, sheets and strip	+425	B 575 – N06455	For certain corrosive conditions	N/A
Ni-Mo-Cr alloy (Hastelloy C276) plates, sheets and strip	+425 (+650)	B 575 – N10276	For certain corrosive conditions	N/A
Ni-Cr-Mo alloy (Hastelloy C22) plates, sheets and strip	(+425)	B 575 – N06022	For certain corrosive conditions	N/A
Titanium plates, sheets and strip	(+300)	B 265 – Grade 2	For certain corrosive conditions; for linings, tensile properties indicated in the material specifications are for info only	For linings, specify soft-annealed material with hardness 140 HV10 max; softer Grade 1 may also be used for lining
Tantalum plates, sheets, and strip	Temp. limits depend on the service	B 708 – R05200	For certain corrosive conditions; for linings, tensile properties indicated in the material specifications are for info only	For linings, specify soft-annealed material with hardness 120 HV10 max

Tubes and Tubing

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Seamless aluminum tubes	-200 to +200	B 234 – Alloy 1060	For unfired heat transfer equipment under certain corrosive conditions	Specify annealed condition for all grades
Seamless Al-2.5 Mg alloy tubes	-200 to +200	B 234 – Alloy 5052	For unfired heat transfer equipment under certain corrosive conditions	Specify annealed condition for all grades
Seamless Al-2.7 Mg-Mn alloy tubes	-200 to +200	B 234 – Alloy 5454	For unfired heat transfer equipment under certain corrosive conditions	Specify annealed condition for all grades
Seamless copper tubing in small sizes	-200 to +150	B 68 – C12200 06 0	For instrument lines	Specify annealed condition for all grades
Seamless Cu-Zn-Al alloy (Aluminum Brass)	(+200) to +175	B 111 – C68700	For coolers and condensers in brackish and seawater service	Specify annealed condition for all grades
Seamless copper-nickel (90/10 Cu-Ni) alloy tubes	-200 to +350	B 111 – C70600	For unfired heat transfer equipment under certain corrosive conditions	Specify annealed condition for all grades
Seamless copper-nickel (70/30 Cu-Ni) alloy tubes	-200 to +350	B 111 – C71500	For unfired heat transfer equipment under certain corrosive conditions	Specify annealed condition for all grades
Seamless copper-nickel (66/30/2/2 Cu-Ni-Fe-Mn) alloy tubes	-200 to +350	B 111 – C71640	For unfired heat transfer equipment under certain corrosive conditions	Specify annealed condition for all grades
Seamless nickel tubes	-200 to +350	B 163 – N02200	For unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless low-carbon nickel tubes	-200 to +350	B 163 – N02201	For unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Cu alloy (Monel 400) tubes	-200 to +400	B 163 – N04400	For unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Cr-Fe alloy (Inconel 600) tubes	+650	B 163 – N06600	For unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Fe-Cr alloy (Incoloy 800) tubes	+815	B 163 – N08800	For unfired heat transfer equipment under certain corrosive conditions	Specify C 0.05% maximum. Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Fe-Cr alloy (Incoloy 800H) tubes	+1000	B 407 – N08810	For furnaces and unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Fe-Cr alloy (Incoloy 800 HT) tubes	(+1000)	B 407 – N08811	For furnaces and unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Cr-Mo-Cu alloy (Incoloy 825) tubes	-200 to +425	B 163 – N08825	For unfired heat transfer equipment under certain corrosive conditions	Specify stabilized annealed condition if tubes are to be welded to headed boxes. Intergranular corrosion testing to be carried out
Seamless Ni-Cr-Mo-Nb alloy (Inconel 625) tubes	+425	B 444 – N06625	For unfired heat transfer equipment under certain corrosive conditions	Grade-1 (annealed) material should be used at service temperatures of 539°C and less. Intergranular corrosion testing to be carried out
Seamless Ni-Mo alloy (Hastelloy B2) tubes	+425	B 622 – N10665	For unfired heat transfer equipment under certain corrosive conditions	Intergranular corrosion testing to be carried out
Welded Ni-Mo alloy (Hastelloy B2) tubes	+425	B 626 – N10665 Class 1A	For unfired heat transfer equipment under certain corrosive conditions	Intergranular corrosion testing to be carried out
Seamless Ni-Mo-Cr alloy (Hastelloy C4) tubes	+425	B 622 – N06455	For unfired heat transfer equipment under certain corrosive conditions	Intergranular corrosion testing to be carried out
Welded Ni-Mo-Cr alloy (Hastelloy C4) tubes	+425	B 626 – N06455 Class 1A	For unfired heat transfer equipment under certain corrosive conditions	Intergranular corrosion testing to be carried out
Seamless Ni-Mo-Cr alloy (Hastelloy C276) tubes	+425 (+650)	B 622 – N10276	For unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Welded Ni-Mo-Cr alloy (Hastelloy C276) tubes	+425 (+650)	B 626 – N10276 Class 1A	For unfired heat transfer equipment under certain corrosive conditions	Specify solution annealed condition for all grades. For tubes intended for use with compression fittings, hardness shall not exceed 90 HRB
Seamless Ni-Cr-Mo alloy (Hastelloy C22) tubes	(+425)	B 622 – N06022	For unfired heat transfer equipment under certain corrosive conditions	Intergranular corrosion testing to be carried out
Welded Ni-Cr-Mo alloy (Hastelloy C22) tubes	(+425)	B 626 – N06022 Class 1A	For unfired heat transfer equipment under certain corrosive conditions	Intergranular corrosion testing to be carried out
Seamless titanium tubes	(+300)	B 338 – Grade 2	For unfired heat transfer equipment under certain corrosive conditions	N/A
Welded titanium tubes	(+300)	B 338 – Grade 2	For unfired heat transfer equipment under certain corrosive conditions	N/A

Pipe

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Seamless aluminum pipe	-200 to +200	B 241 – Alloy 1060	For certain corrosive conditions	Specify annealed condition for all grades.
Seamless Al-Mg-Si alloy pipe	-200 to +200	B 241 – Alloy 6061	For certain corrosive conditions	Specify annealed condition for all grades.
Seamless Al-Mg-Si alloy pipe	-200 to +200	B 241 – Alloy 6063	For pipelines under certain corrosive conditions	Specify annealed condition for all grades.
Seamless Al-Mg alloy pipe	-200 to +200	B 241 – Alloy 5052	For general use under certain corrosive conditions	Specify annealed condition for all grades.
Seamless Al-2.7Mg-Mn alloy pipe	-200 to +200	B 241 – Alloy 5454	For general use under certain corrosive conditions	Specify annealed condition for all grades.
Seamless Al-4.5Mg-Mn alloy pipe	-200 to +65	B 241 – Alloy 5083	For low-temperature service only	Specify annealed condition for all grades.
Seamless copper pipe	-200 to +200	B 42 – C12200	For certain corrosive conditions	Specify annealed condition for all grades.
Seamless Cu-Zn-Al alloy pipe (Aluminum Brass)	-200 to +175	B 111 – C68700	For brackish and seawater service	Specify annealed condition for all grades.
Seamless Cu-Ni alloy (90/10 Cu-Ni) pipe	-200 to +350	B 466 – C70600	For seawater service	Specify annealed condition for all grades.
Seamless Cu-Ni alloy (70/30 Cu-Ni) pipe	-200 to +350	B 466 – C71500	For certain corrosive conditions	Specify annealed condition for all grades.
Seamless nickel pipe	-200 to +350	B 161 – N02200	For certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades.
Seamless low-carbon nickel pipe	-200 to +350	B 161 – N02201	For certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades.
Seamless Ni-Fe-Cr alloy (Incoloy 800) pipe	-200 to +815	B 407 – N08800	For high-temperature conditions and/or certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades. Specify C 0.05% max.
Seamless Ni-Fe-Cr alloy (Incoloy 800H) pipe	+1000	B 407 – N08810	For high-temperature conditions and/or certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades.
Seamless Ni-Fe-Cr alloy (Incoloy 800HT) pipe	+1000	B 407 – N08811	For high-temperature conditions and/or certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades.
Seamless Ni-Cr-Fe alloy (Inconel 600) pipe	+650	B 167 – N06600	For high-temperature conditions and/or certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades.
Cu alloy (Monel 400) pipe	+400	N04400	For certain corrosive conditions	Specify annealed and pickled condition for all grades.
Seamless Ni-Fe-Cr-Mo-Cu alloy (Incoloy 825) pipe	-200 to +425	B 423 – N08825	For certain corrosive conditions	Specify cold-worked, annealed, and pickled condition for all grades. Must pass intergranular corrosion test (ASTM A262). Corrosion rate ≤ 0.3 mm/year.
Welded Ni-Fe-Cr-Mo-Cu alloy (Incoloy 825) pipe	-200 to +425	B 705 – N08825 Class 2	For certain corrosive conditions	Specify cold-worked and bright annealed condition. Must pass intergranular corrosion test (ASTM A262). Corrosion rate ≤ 0.3 mm/year.
Seamless Ni-Cr-Mo-Nb alloy (Inconel 625) pipe	+425	B 444 – N06625	For certain corrosive conditions	Specify cold-worked and bright annealed condition for all grades.
Welded Ni-Cr-Mo-Nb alloy (Inconel 625) pipe	+425	B 705 – N06625 Class 2	For certain corrosive conditions	Specify cold-worked and bright annealed condition.
Seamless Ni-Mo alloy (Hastelloy B2) pipe	+425	B 622 – N10665	For certain corrosive conditions
Welded Ni-Mo alloy (Hastelloy B2) pipe	+425	B 619 – N10665	For certain corrosive conditions
Seamless Ni-Mo alloy (Hastelloy C4) pipe	+425	B 622 – N06455	For certain corrosive conditions
Welded Ni-Mo-Cr alloy (Hastelloy C4) pipe	+425	B 619 – N06455 Class II	For certain corrosive conditions
Seamless Ni-Mo-Cr alloy (Hastelloy C276) pipe	+425 to +650	B 622 – N10276	For certain corrosive conditions
Welded Ni-Mo-Cr alloy (Hastelloy C276) pipe	+425 to +650	B 619 – N10276 Class II	For certain corrosive conditions
Seamless Ni-Cr-Mo alloy (Hastelloy C22) pipe	+425	B 622 – N06022	For certain corrosive conditions
Welded Ni-Cr-Mo alloy (Hastelloy C22) pipe	+425	B 619 – N06022 Class II	For certain corrosive conditions
Seamless titanium pipe	(+300)	B 338 – Grade 2	For certain corrosive conditions
Welded titanium pipe	(+300)	B 338 – Grade 2	For certain corrosive conditions
Seamless titanium pipe for corrosive condition	+300	B861 Grade 2 bright annealed
Welded titanium pipe for corrosive condition	+300	B862 Grade 2 bright annealed

Forgings, Flanges and Fittings

Designation	Metal Temp. (°C)	ASTM	Remarks	Added Requirements
Al-2.5Mg alloy forgings	-200 to +200	Alloy 5052	For general use under certain corrosive conditions	Specify annealed condition for all grades. Order to ASTM B 247, ASME VIII, Div. 1, para UG 15.
Al-2.7Mg-Mn alloy forgings	-200 to +200	Alloy 5454	For general use under certain corrosive conditions	Specify annealed condition for all grades. Order to ASTM B 247, ASME VIII, Div. 1, para UG 15.
Al-4.5Mg-Mn alloy forgings	-200 to +65	B 247 – Alloy 5083	For low-temperature service only	Specify annealed condition for all grades.
Al-Mg-Si alloy forgings	-200 to +200	B 247 – Alloy 6061	For certain corrosive conditions and/or low-temperature service	Specify annealed condition for all grades.
Al-Mg-Si alloy welding fittings	-200 to +200	B 361 – WP 6061	For certain corrosive conditions and/or low-temperature service	Specify annealed condition for all grades.
Al-2.5Mg alloy welding fittings	-200 to +200	Alloy WP 5052 or WP 5052W	For marine atmosphere and general use under certain corrosive conditions	Specify annealed condition for all grades. Order to ASTM B 361, ASME VIII, Div. 1, para UG 15.
Al-2.7Mg-Mn alloy welding fittings	-200 to +200	Alloy WP 5454 or WP 5454W	For marine atmosphere and general use under certain corrosive conditions	Specify annealed condition for all grades. Order to ASTM B 361, ASME VIII, Div. 1, para UG 15.
Nickel welding fittings	(+325)	B 366 – WPNS or WPNW	For certain corrosive conditions	Specify annealed condition for all grades.
Low-carbon nickel welding fittings	(+600)	B 366 – WPNL or WPNLW	For certain corrosive conditions	Specify annealed condition for all grades.
Ni-Cu alloy (Monel 400) forgings	-200 to +400	B 564 – N04400	For certain corrosive conditions	Specify solution annealed condition for all grades.
Ni-Cu alloy (Monel 400) welding fittings	-200 to +400	B 366 – WPNCS or WPNCW	For certain corrosive conditions	Specify solution annealed condition for all grades.
Ni-Cu alloy (Monel 400) forgings	+650	B 564 – N06600	For high temperature conditions and/or certain corrosive conditions	Specify solution annealed condition for all grades.
Ni-Cr-Fe alloy (Inconel 600) forgings	+650	B 366 – WPNCS or WPNC1W	For high temperature conditions and/or certain corrosive conditions	Specify solution annealed condition for all grades.
Ni-Fe-Cr alloy (Incoloy 800) forgings	+815	B 564 – Alloy N08800	For extreme temperature service	Specify solution annealed condition for all grades. Specify C ≤ 0.05%.
Ni-Fe-Cr alloy (Incoloy 800H) forgings	+1000	B 564 – N08810	For extreme temperature service	Specify solution annealed condition for all grades. Appropriate Corrosion Testing to be carried out.
Ni-Fe-Cr-Mo-Cu alloy (Incoloy 825) forgings	(-200) to +450	B 564 – N08825	For extreme temperature service	Specify solution annealed condition for all grades. The material shall be capable of passing the Practice C intergranular corrosion test as specified in ASTM A262 (Corrosion rate in this test shall not exceed 0.3 mm/year).
Ni-Fe-Cr-Mo alloy	(-200)	B 366 –	For extreme temperature service	Specify solution annealed condition. Intergranular Corrosion Testing to be carried out.
Cu alloy (Incoloy 825) welding fittings	+450	WPNI CMCS or WPNI CMCW		Specify solution annealed condition for all grades. The material shall be capable of passing the Practice C intergranular corrosion test as specified in ASTM A262 (Corrosion rate in this test shall not exceed 0.3 mm/year).
Ni-Mo alloy (Hastelloy B2) welding fittings	+425	B 366 – WPHB2S or WPHB2W	For certain corrosive conditions	Specify solution annealed condition for all grades.
Ni-Mo-Cr alloy (Hastelloy C4) welding fittings	+425	B 366 – WPHC4	For certain corrosive conditions	Specify solution annealed condition for all grades. Intergranular Corrosion Testing to be carried out.
Ni-Mo-Cr alloy (Hastelloy C276) welding fittings	+800	B 366 – WPHC276	For certain corrosive conditions	Specify solution annealed condition for all grades. Intergranular Corrosion Testing to be carried out.
Ni-Cr-Mo alloy (Hastelloy C22) forgings	+425	B 564 – N06022	For certain corrosive conditions	Specify solution annealed condition for all grades.
Ni-Cr-Mo alloy (Hastelloy C22) welding fittings	+425	B 366 – WPHC22S or WPHC22W	For certain corrosive conditions	Specify solution annealed condition for all grades. Intergranular Corrosion Testing to be carried out.
Titanium forgings	+300	B 381 – Grade F2	For certain corrosive conditions	Specify annealed condition for all grades.
Titanium welding fittings	+300	B 363 – WPT2 or WPT2W	For certain corrosive conditions	Specify annealed condition for all grades.

Castings

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Al-Si alloy castings	-200 to +200	B 26 – Alloy B443.0	For certain corrosive conditions	Specify B100 Alloy B443.0 for permanent mold castings.
Al-12Si alloy castings	-200 to +200	–	For certain corrosive conditions	–
Composition bronze (Bronze 85/5/5/5) castings	-200 to +175	B 62 – C83600	For flanges, fittings, and valves	–
Tin bronze (Bronze 88/10/2) castings	-200 to +175	B 584 – C90500	For equipment parts to be used in brackish and seawater service and for certain corrosive conditions	–
Ni-Al bronze castings	-200 to +350	B 148 – C95800	For equipment parts to be used in brackish and seawater service and for certain corrosive conditions	–
Lead in pig form	+100	B 29 – Chemical – Copper Lead UNS L55112	For homogeneous linings of equipment under certain corrosive conditions	–
Ni-Cu alloy (Monel 400) castings	-200 to +400	A 494 – M35-1	For certain corrosive conditions	–
Ni-Mo alloy (Hastelloy B2) castings	+425	A 494 – N-7M Class 1	For certain corrosive conditions	–
Ni-Mo-Cr alloy (Hastelloy C4) castings	+425	A 494 – CW-2M	For certain corrosive conditions	–
Ni-Mo-Cr alloy (Hastelloy C276) castings	+425 to +650	A 494 – CW-12MW Class 1	For certain corrosive conditions	–
50Cr-50Ni-Nb alloy castings	+1000	A560 – 50Cr-50Ni-Cb	For furnace tube supports exposed to vanadium attack	–
Titanium castings	+250	B367 – Grade C2	For certain corrosive conditions	–

Bars, Sections and Wire

DESIGNATION	Metal Temp. (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Extruded aluminum bars, rods, sections (incl. hollow sections), tube, and wire	-200 to +200	B 221 – Alloy 1060	For certain corrosive conditions	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Extruded Al-2.5 Mg alloy bars, rods, sections (incl. hollow sections), tube, and wire	-200 to +200	B 221 – Alloy 5052	For general use under certain corrosive conditions	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Extruded Al-2.7 Mg-Mn alloy bars, rods, sections (incl. hollow sections), tube, and wire	-200 to +200	B 221 – Alloy 5454	For general use under certain corrosive conditions	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Extruded Al-Mg-Si alloy bars, rods, sections	-200 to +200	B 221 – Alloy 6063	For general purposes	For bars, rods, and sections, specify annealed condition for all grades.
Copper bars, rods, and sections	-200 to +150	B 133 – C11000	For electrical purposes	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Copper bars, rods, and sections	-200 to +150	B 133 – C12200	For general purposes	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Free cutting Cu-Zn alloy bars, rods, and sections	-200 to +175	B 16 – C36000	For general purposes	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Cu-Zn-Pb alloy bars, rods, and sections	-200 to +150	B140 – C32000 or C31400	For general purposes	For bars, rods, and sections, specify annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Cu-Al alloy bars, rods, and sections	-200 to +350	B 150 – C63200	For general purposes under certain corrosive conditions	–
Cu-Ni (90/10) alloy bars, rods, and sections	-200 to +350	B 122 – C706	For certain corrosive conditions	–
Cu-Ni (70/30) alloy bars, rods, and sections	-200 to +350	B 122 – C71500	For certain corrosive conditions	–
Phosphor bronze wire	-200 to +175	B 159 – C51000 Condition H08 (Spring Temper)	For springs	–
Nickel bars and rods	(+325)	B 160 – N02200	For certain corrosive conditions	For bars and rods, specify solution annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Low-carbon nickel bars and rods	-200 +350	B 160 – N02201	For certain corrosive conditions	For bars and rods, specify solution annealed condition for all grades. For wire, condition to be agreed upon for each case individually.
Ni-Cu alloy (Monel 400) bars, rods and wire	-200 +400	B 164 – N04400	For certain corrosive conditions	For bars and rods, specify solution annealed condition for all grades. For wire, conditions to be agreed upon for each case individually.
Ni-Cu-Al alloy (Monel K500) bars, rods and wire	-200 +400	–	For certain corrosive conditions requiring high tensile strength	Bars and rods should be supplied in the solution-treated and precipitation-hardened condition.
Ni-Cr-Fe alloy (Inconel 600) bars, rods and wire	+650	B 166 – N06600	For high-temperature conditions and/or certain corrosive conditions	For bars and rods, specify the solution annealed condition for all grades. For wire, conditions to be agreed upon for each case individually.
Ni-Cr-Mo-Nb alloy (Inconel 625) bars and rods	+425	B 446 – N06625	For certain corrosive conditions	For bars and rods, specify the solution annealed condition for all grades. For wire, conditions to be agreed upon for each case individually.
Ni-Fe-Cr alloy (Incoloy 800) bars, rods and wire	+815	B 408 – N08800	For high-temperature conditions and/or certain corrosive conditions	Specify C 0.05% max.
Ni-Fe-Cr alloy (Incoloy 800HT) bars, rods and wire	+1000	B 408 – N08810	For high-temperature conditions and/or certain corrosive conditions	–
Ni-Fe-Cr alloy (Incoloy 800H) bars, rods and wire	(+1000)	B 408 – N08811	For high-temperature conditions and/or certain corrosive conditions	–
Ni-Fe-Cr-Mo-Cu alloy (Incoloy 825) bars, rods and wire	(+425)	B 425 – N08825	For certain corrosive conditions	Intergranular Corrosion Testing to be carried out.
Ni-Mo alloy (Hastelloy B2) bars and rods	(+425)	B 335 – N10665	For certain corrosive conditions	–
Ni-Mo-Cr alloy (Hastelloy C4) rods	(+425)	B 574 – N06455	For certain corrosive conditions	–
Ni-Mo-Cr alloy (Hastelloy C276) rods	(+800)	B 574 – N10276	For certain corrosive conditions	–
Ni-Cr-Mo alloy (Hastelloy C22) rods for certain corrosive conditions	(+425)	B 574 – N06022	For certain corrosive conditions	–
Titanium bars	(+300)	B 348 – Grade 2	For certain corrosive conditions	Specify annealed condition.

Bolting

DESIGNATION	Metal Temp (°C)	ASTM	REMARKS	ADDED REQUIREMENTS
Aluminum alloy bolts and nuts	-200 +200	F467/468 – A96061	Bolting material may also be selected from Bars specified in the Table above.	–
Cu-Al alloy bolts and nuts	-200 +365	F467/468 – C63000	Bolting material may also be selected from Bars specified in the Table above.	–
Cu-Ni (70/30) alloy bolts and nuts	-200 +350	F467/468 – C71500	Bolting material may also be selected from Bars specified in the Table above.	–
Ni-Cu alloy (Monel 400) bolts and nuts	-200 +400	F467/468 – N04400	Bolting material may also be selected from Bars specified in the Table above.	–
Ni-Cu-Al alloy (Monel K500) bolts and nuts	-200 +400	F467/468 – N05500	Bolting material may also be selected from Bars specified in the Table above.	–
Ni-Mo alloy (Hastelloy B) bolts and nuts	+425	F467/468 – N10001	Bolting material may also be selected from Bars specified in the Table above.	–
Ni-Mo-Cr alloy (Hastelloy C276) bolts and nuts	(+800)	F467/468 – N10276	Bolting material may also be selected from Bars specified in the Table above.	–
Titanium bolts and nuts	(+300)	F467/468 – Alloy Ti 2	Bolts are primarily intended for use inside equipment.	–

Conclusion: Choosing the Right Materials for Your Project as per Material Selection Guidelines

Choosing the correct material as per Material Selection Guidelines for industrial applications is a nuanced process that balances factors such as corrosion resistance, mechanical strength, thermal stability, and cost-effectiveness. Nickel alloys, Monel, Hastelloy, and titanium stand out for their ability to perform under extreme conditions, making them invaluable in industries like oil and gas, aerospace, and chemical processing. By aligning material properties with operational requirements, businesses can enhance safety, reduce maintenance costs, and extend equipment lifespan. Ultimately, informed material selection leads to greater operational efficiency and ensures that systems remain reliable, even in the most challenging environments.

All You Need to Know: Super 13Cr

October 11, 2024/in Industry Knowledge/by Energy Steel

1. Introduction and Overview

Super 13Cr is a martensitic stainless steel alloy known for its exceptional mechanical strength and moderate corrosion resistance, making it ideal for demanding environments. Originally developed for oil and gas applications, Super 13Cr offers a cost-effective alternative to higher alloyed materials, especially in moderately corrosive environments where chloride-induced stress corrosion cracking (SCC) is a concern.

Due to its enhanced mechanical properties and improved corrosion resistance compared to conventional 13Cr stainless steel, Super 13Cr is widely used in industries like oil and gas, chemical processing, pulp and paper, marine and offshore, air pollution control, and power generation.

2. Available Super 13Cr Products and Specifications

Super 13Cr is available in a variety of forms to meet diverse application requirements:

UNS Number: S41426
Common Name: Super 13Cr
W.Nr.: 1.4009
ASTM/ASME Standards: ASTM A276, A479, A182
Product Forms: Pipe, Tube, Bar, Rod, Forging Stock

3. Applications of Super 13Cr

Super 13Cr’s combination of strength, hardness, and corrosion resistance makes it suitable for various applications:

Oil and Gas: Tubing, casing, and pipelines in mildly corrosive environments with CO₂ and limited H₂S exposure.
Chemical Processing: Equipment and piping systems handling moderately aggressive chemicals.
Pulp and Paper: Components exposed to harsh chemical processing environments.
Marine and Offshore: Components in seawater handling, including pumps, valves, and other marine structures.
Power Generation: Steam turbine blades and components are exposed to high temperatures and corrosion.
Air Pollution Control: Components exposed to aggressive flue gases and acidic environments.
Food Processing: Equipment used in environments where hygiene and corrosion resistance are critical.
High-Efficiency Residential Furnaces: Heat exchangers due to the material’s durability under high temperatures.

4. Corrosion Resistance Properties

Super 13Cr offers better corrosion resistance than conventional 13Cr stainless steel, particularly in environments containing CO₂. However, it is not suitable for environments with significant H₂S content due to the risk of sulfide stress cracking. The alloy provides good pitting and crevice corrosion resistance in chloride-containing environments and is resistant to stress corrosion cracking under moderate chloride concentrations.

5. Physical and Thermal Properties

Density: 7.7 g/cm³
Melting Range: 1,400–1,450°C
Thermal Conductivity: 25 W/mK at 20°C
Specific Heat: 460 J/kg·K
Thermal Expansion Coefficient: 10.3 x 10⁻⁶/°C (20–100°C)

6. Chemical Composition

Typical chemical composition of Super 13Cr includes:

Chromium (Cr): 12.0–14.0%
Nickel (Ni): 3.5–5.5%
Molybdenum (Mo): 1.5–2.5%
Carbon (C): ≤0.03%
Manganese (Mn): ≤1.0%
Silicon (Si): ≤1.0%
Phosphorus (P): ≤0.04%
Sulfur (S): ≤0.03%
Iron (Fe): Balance

7. Mechanical Properties

Tensile Strength: 690–930 MPa
Yield Strength: 550–650 MPa
Elongation: ≥20%
Hardness: 250–320 HB
Impact Toughness: Excellent, especially after heat treatment.

8. Heat Treatment

Super 13Cr is typically hardened through heat treatment to improve its mechanical properties. The heat treatment process involves quenching and tempering to achieve the desired combination of strength and toughness. The typical heat treatment cycle includes:

Solution Annealing: Heating to 950–1050°C, followed by rapid cooling.
Tempering: Reheating to 600–700°C to adjust hardness and toughness.

9. Forming

Super 13Cr can be hot or cold-formed, although it is more challenging to form than austenitic grades due to its higher strength and lower ductility. Preheating before forming and post-forming heat treatments are often necessary to avoid cracking.

10. Welding

Welding Super 13Cr requires careful control to avoid cracking and maintain corrosion resistance. Preheat and post-weld heat treatment (PWHT) are typically required. Filler materials should be compatible with Super 13Cr to ensure weld quality. Special care must be taken to avoid hydrogen embrittlement.

11. Corrosion of Welds

Welds in Super 13Cr can be susceptible to localized corrosion, particularly in the heat-affected zone (HAZ). Post-weld heat treatment is critical to restore corrosion resistance, reduce residual stresses, and improve toughness in the welded area.

12. Descaling, Pickling, and Cleaning

Descaling of Super 13Cr can be challenging due to the formation of a tough oxide scale during heat treatment. Mechanical methods like blasting or chemical treatments using pickling solutions can be employed to remove scale. The alloy requires thorough cleaning after pickling to avoid contamination and ensure optimal corrosion resistance.

13. Surface Hardening

Super 13Cr can undergo surface hardening treatments like nitriding to enhance its wear resistance without compromising its corrosion resistance. Nitriding helps improve the alloy’s durability in abrasive and high-friction environments.

Conclusion

Super 13Cr offers a versatile solution for industries where moderate corrosion resistance and high mechanical strength are required. Its balanced properties make it a popular choice in oil and gas, chemical processing, and marine applications, among others. By understanding its unique characteristics—from corrosion resistance to weldability—engineers and materials specialists can make informed decisions to optimize performance and longevity in their specific environments.

This blog post provides a comprehensive overview of Super 13Cr’s specifications and properties, equipping industries with the knowledge to make the best use of this advanced material.