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Exploring the Vital Role of Steel Pipes in Oil & Gas Exploration

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I. The Basic Knowledge of the Pipe for Oil and Gas Industry

1. Terminology Explanation

API: Abbreviation of American Petroleum Institute.
OCTG: Abbreviation of Oil Country Tubular Goods, including Oil Casing Pipe, Oil Tubing, Drill Pipe, Drill Collar, Drill Bits, Sucker Rod, Pup joints, etc.
Oil Tubing: Tubing is used in oil wells for oil extraction, gas extraction, water injection, and acid fracturing.
Casing: Tubing that is lowered from the ground surface into a drilled borehole as a liner to prevent wall collapse.
Drill Pipe: Pipe used for drilling boreholes.
Line Pipe: Pipe used to transport oil or gas.
Couplings: Cylinders used to connect two threaded pipes with internal threads.
Coupling Material: Pipe used for manufacturing couplings.
API Threads: Pipe threads specified by API 5B standard, including oil pipe round threads, casing short round threads, casing long round threads, casing partial trapezoidal threads, line pipe threads, and so on.
Premium Connection: Non-API threads with special sealing properties, connection properties, and other properties.
Failures: deformation, fracture, surface damage, and loss of original function under specific service conditions.
Main Forms of Failure: crushing, slipping, rupture, leakage, corrosion, bonding, wear, and so on.

2. Petroleum Related Standards

API Spec 5B, 17th Edition – Specification for Threading, Gauging, and Thread Inspection of Casing, Tubing, and Line Pipe Threads
API Spec 5L, 46th Edition – Specification for Line Pipe
API Spec 5CT, 11th Edition – Specification for Casing and Tubing
API Spec 5DP, 7th Edition – Specification for Drill Pipe
API Spec 7-1, 2nd Edition – Specification for Rotary Drill Stem Elements
API Spec 7-2, 2nd Edition – Specification for Threading and Gauging of Rotary Shouldered Thread Connections
API Spec 11B, 24th Edition – Specification for Sucker Rods, Polished Rods and Liners, Couplings, Sinker Bars, Polished Rod Clamps, Stuffing Boxes and Pumping Tees
ISO 3183:2019 – Petroleum and Natural Gas Industries — Steel Pipe for Pipeline Transportation Systems
ISO 11960:2020 – Petroleum and Natural Gas Industries — Steel Pipes for Use as Casing or Tubing for Wells
NACE MR0175 / ISO 15156:2020 – Petroleum and Natural Gas Industries — Materials for Use in H2S-Containing Environments in Oil and Gas Production

II. Oil Tubing

1. Classification of Oil Tubing

Oil Tubing is divided into Non-Upsetted Oil Tubing (NU), External Upsetted Oil Tubing (EU), and Integral Joint (IJ) Oil Tubing. NU oil tubing means that the end of the tubing is of normal thickness and directly turns the thread and brings the couplings. Upsetted tubing means that the ends of both tubes are externally Upsetted, then threaded and coupled. Integral Joint tubing means that one end of the tube is Upsetted with external threads and the other end is Upsetted with internal threads and connected directly without couplings.

2. Function of Oil Tubing

① Extraction of oil and gas: after the oil and gas wells are drilled and cemented, the tubing is placed in the oil casing to extract oil and gas to the ground.
② Water injection: when the downhole pressure is insufficient, inject water into the well through the tubing.
③ Steam injection: In thick oil hot recovery, steam is to be input into the well with insulated oil tubing.
④ Acidification and fracturing: In the late stage of well drilling or to improve the production of oil and gas wells, it is necessary to input acidification and fracturing medium or curing material to the oil and gas layer, and the medium and the curing material are transported through the oil tubing.

3. Steel Grade of Oil Tubing

The steel grades of oil tubing are H40, J55, N80, L80, C90, T95, P110.
N80 is divided into N80-1 and N80Q, the two have the same tensile properties of the same, the two differences are the delivery status and impact performance differences, N80-1 delivery by normalized state or when the final rolling temperature is greater than the critical temperature Ar3 and tension reduction after air cooling and can be used to find hot rolling instead of normalized, impact and non-destructive testing are not required; N80Q must be tempered (quenched and tempered) Heat treatment, impact function should be in line with the provisions of API 5CT, and should be non-destructive testing.
L80 is divided into L80-1, L80-9Cr and L80-13Cr. Their mechanical properties and delivery status are the same. Differences in use, production difficulty, and price, L80-1 for the general type, L80- 9Cr and L80-13Cr are high corrosion resistance tubing, production difficulty, expensive, and usually used in heavy corrosion wells.
C90 and T95 are divided into 1 and 2 types, namely C90-1, C90-2 and T95-1, T95-2.

4. The Oil Tubing Commonly Used Steel Grade, Steel Name and Delivery Status

J55 (37Mn5) NU Oil Tubing: Hot rolled instead of Normalised
J55 (37Mn5) EU Oil Tubing: Full-length Normalized after upsetting
N80-1 (36Mn2V) NU Oil Tubing: Hot-rolled instead of Normalised
N80-1 (36Mn2V) EU Oil Tubing: Full-length Normalized after upsetting
N80-Q (30Mn5) Oil Tubing: 30Mn5, Full-length Tempering
L80-1 (30Mn5) Oil Tubing: 30Mn5, Full-length Tempering
P110 (25CrMnMo) Oil Tubing: 25CrMnMo, Full-length Tempering
J55 (37Mn5) Coupling: Hot rolled on-line Normalised
N80 (28MnTiB) Coupling: Full-length Tempering
L80-1 (28MnTiB) Coupling: Full-length Tempered
P110 (25CrMnMo) Coupling: Full-length Tempering

III. Casing Pipe

1. Classification and Role of Casing

The casing is the steel pipe that supports the wall of oil and gas wells. Several layers of casing are used in each well according to different drilling depths and geological conditions. Cement is used to cement the casing after it is lowered into the well, and unlike oil pipe and drill pipe, it cannot be reused and belongs to disposable consumable materials. Therefore, the consumption of casing accounts for more than 70 percent of all oil well pipes. The casing can be divided into conductor casing, intermediate casing, production casing, and liner casing according to its use, and their structures in oil wells are shown in Figure 1.

①Conductor Casing: Typically using API grades K55, J55, or H40, conductor casing stabilizes the wellhead and isolates shallow aquifers with diameters commonly around 20 inches or 16 inches.

②Intermediate Casing: Intermediate casing, often made from API grades K55, N80, L80, or P110, is used to isolate unstable formations and varying pressure zones, with typical diameters of 13 3/8 inches, 11 3/4 inches, or 9 5/8 inches.

③Production Casing: Constructed from high-grade steel such as API grades J55, N80, L80, P110, or Q125, production casing is designed to withstand production pressures, commonly with diameters of 9 5/8 inches, 7 inches, or 5 1/2 inches.

④Liner Casing: Liners extend the wellbore into the reservoir, using materials like API grades L80, N80, or P110, with typical diameters of 7 inches, 5 inches, or 4 1/2 inches.

⑤Tubing: Tubing transports hydrocarbons to the surface, using API grades J55, L80, or P110, and is available in diameters of 4 1/2 inches, 3 1/2 inches, or 2 7/8 inches.

IV. Drill pipe

1. Classification and Function of Pipe for Drilling Tools

The square drill pipe, drill pipe, weighted drill pipe, and drill collar in drilling tools form the drill pipe. The drill pipe is the core drilling tool that drives the drill bit from the ground to the bottom of the well, and it is also a channel from the ground to the bottom of the well. It has three main roles:

① To transmit torque to drive the drill bit to drill;

② To rely on its weight to the drill bit to break the pressure of the rock at the bottom of the well;

③ To transport washing fluid, that is, drilling mud through the ground through the high-pressure mud pumps, drilling column into the borehole flow into the bottom of the well to flush the rock debris and cool the drill bit, and carry the rock debris through the outer surface of the column and the wall of the well between the annulus to return to the ground, to achieve the purpose of drilling the well.

The drill pipe in the drilling process to withstand a variety of complex alternating loads, such as tensile, compression, torsion, bending, and other stresses, the inner surface is also subject to high-pressure mud scouring and corrosion.
(1) Square Drill Pipe: square drill pipe has two kinds quadrilateral type and hexagonal type, China’s petroleum drill pipe each set of drill columns usually uses a quadrilateral type drill pipe. Its specifications are 63.5mm (2-1/2 inches), 88.9mm (3-1/2 inches), 107.95mm (4-1/4 inches), 133.35mm (5-1/4 inches), 152.4mm (6 inches) and so on. Usually, the length used is 12~14.5m.
(2) Drill Pipe: The drill pipe is the main tool for drilling wells, connected to the lower end of the square drill pipe, and as the drilling well continues to deepen, the drill pipe keeps lengthening the drill column one after another. The specifications of drill pipe are: 60.3mm (2-3/8 inches), 73.03mm (2-7/8 inches), 88.9mm (3-1/2 inches), 114.3mm (4-1/2 inches), 127mm (5 inches), 139.7mm (5-1/2 inches) and so on.
(3) Heavy Duty Drill Pipe: A weighted drill pipe is a transitional tool connecting the drill pipe and drill collar, which can improve the force condition of the drill pipe and increase the pressure on the drill bit. The main specifications of the weighted drill pipe are 88.9mm (3-1/2 inches) and 127mm (5 inches).
(4) Drill Collar: the drill collar is connected to the lower part of the drill pipe, which is a special thick-walled pipe with high rigidity, exerting pressure on the drill bit to break the rock, and playing a guiding role when drilling a straight well. The common specifications of drill collars are 158.75mm (6-1/4 inches), 177.85mm (7 inches), 203.2mm (8 inches), 228.6mm (9 inches) and so on.

V. Line pipe

1. Classification of Line Pipe

Line pipe is used in the oil and gas industry for the transmission of oil, refined oil, natural gas, and water pipelines with the abbreviation of steel pipe. Conveying oil, and gas pipelines is mainly divided into mainline pipelines, branch line pipelines, and urban pipeline network pipelines three kinds of mainline pipeline transmission of the usual specifications for  ∅406 ~ 1219mm, wall thickness of 10 ~ 25mm, steel grade X42 ~ X80; branch line pipeline and urban pipeline network pipelines are usually specification for the ∅114 ~ 700mm, wall thickness of 6 ~ 20mm, the steel grade for the X42 ~ X80. The steel grade is X42～X80. Line pipe is available as welded type and seamless type. Welded Line Pipe is used more than Seamless Line Pipe.

2. Standard of Line Pipe

API Spec 5L – Specification for Line Pipe
ISO 3183 – Petroleum and Natural Gas Industries — Steel Pipe for Pipeline Transportation Systems

3. PSL1 and PSL2

PSL is the abbreviation of Product Specification Level. Line pipe product specification level is divided into PSL 1 and PSL 2, can also be said that the quality level is divided into PSL 1 and PSL 2. PSL 2 is higher than PSL 1, the 2 specification levels not only have different test requirements, but the chemical composition and mechanical properties requirements are different, so according to API 5L order, the terms of the contract in addition to specifying the specifications, steel grade and other common indicators, but also must indicate the product Specification level, that is, PSL 1 or PSL 2. PSL 2 in the chemical composition, tensile properties, impact power, non-destructive testing, and other indicators are stricter than PSL 1.

4. Line Pipe Steel Grade, Chemical Composition and Mechanical Properties

Line pipe steel grade from low to high is divided into: A25, A, B, X42, X46, X52, X60, X65, X70, and X80. For the detailed Chemical Composition and Mechanical Properties, please refer to API 5L Specification, 46th Edition Book.

5. Line Pipe Hydrostatic Test and Non-destructive Examination Requirements

Line pipe should be done branch by branch hydraulic test, and the standard does not allow non-destructive generation of hydraulic pressure, which is also a big difference between the API standard and our standards. PSL 1 does not require non-destructive testing, PSL 2 should be non-destructive testing branch by branch.

VI. Premium Connections

1. Introduction of Premium Connections

Premium Connection is a pipe thread with a special structure different from the API thread. Although the existing API threaded oil casing is widely used in oil well exploitation, its shortcomings are clearly shown in the special environment of some oil fields: the API round threaded pipe column, although its sealing performance is better, the tensile force borne by the threaded part is only equivalent to 60% to 80% of the strength of the pipe body, and thus it can’t be used in the exploitation of deep wells; the API biased trapezoidal threaded pipe column, although its tensile performance is much higher than that of the API round threaded connection, its sealing performance is not so good. Although the tensile performance of the column is much higher than that of the API round thread connection, its sealing performance is not very good, so it can not be used in the exploitation of high-pressure gas wells; in addition, the threaded grease can only play its role in the environment with the temperature below 95℃, so it can not be used in the exploitation of high-temperature wells.

Compared with the API round thread and partial trapezoidal thread connection, the premium connection has made breakthrough progress in the following aspects:

(1) Good sealing, through the elasticity and metal sealing structure design, makes the joint gas sealing resistant to reaching the limit of the tubing body within the yield pressure;

(2) High strength of the connection, connecting with special buckle connection of oil casing, its connection strength reaches or exceeds the strength of the tubing body, to solve the problem of slippage fundamentally;

(3) By the Material selection and surface treatment process improvement, basically solved the problem of thread sticking buckle;

(4) Through the optimization of the structure, so that the joint stress distribution is more reasonable and more conducive to the resistance to stress corrosion;

(5) Through the shoulder structure of the reasonable design, so that the operation of the buckle on the operation is easier to carry out.

At present, the oil and gas industry boasts over 100 patented premium connections, representing significant advancements in pipe technology. These specialized thread designs offer superior sealing capabilities, increased connection strength, and enhanced resistance to environmental stresses. By addressing challenges such as high pressures, corrosive environments, and temperature extremes, these innovations ensure greater reliability and efficiency in oil well operations worldwide. Continual research and development in premium connections underscore their pivotal role in supporting safer and more productive drilling practices, reflecting an ongoing commitment to technological excellence in the energy sector.

VAM® Connection: Known for its robust performance in challenging environments, VAM® connections feature advanced metal-to-metal sealing technology and high torque capabilities, ensuring reliable operations in deep wells and high-pressure reservoirs.

TenarisHydril Wedge Series: This series offers a range of connections such as Blue®, Dopeless®, and Wedge 521®, known for their exceptional gas-tight sealing and resistance to compression and tension forces, enhancing operational safety and efficiency.

TSH® Blue: Designed by Tenaris, TSH® Blue connections utilize a proprietary double shoulder design and a high-performance thread profile, providing excellent fatigue resistance and ease of make-up in critical drilling applications.

Grant Prideco™ XT® Connection: Engineered by NOV, XT® connections incorporate a unique metal-to-metal seal and a robust thread form, ensuring superior torque capacity and resistance to galling, thereby extending the operational life of the connection.

Hunting Seal-Lock® Connection: Featuring a metal-to-metal seal and a unique thread profile, the Seal-Lock® connection by Hunting is renowned for its superior pressure resistance and reliability in both onshore and offshore drilling operations.

Conclusion

In conclusion, the intricate network of pipes crucial to the oil and gas industry encompasses a wide array of specialized equipment designed to withstand rigorous environments and complex operational demands. From the foundational casing pipes that support and protect well walls to the versatile tubing used in extraction and injection processes, each type of pipe serves a distinct purpose in the exploration, production, and transportation of hydrocarbons. Standards like API specifications ensure uniformity and quality across these pipes, while innovations such as premium connections enhance performance in challenging conditions. As technology evolves, these critical components continue to advance, driving efficiency and reliability in global energy operations. Understanding these pipes and their specifications underscores their indispensable role in the modern energy sector’s infrastructure.

Why Do We Use Steel Line Pipes to Transport Oil and Gas?

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In the oil and gas industry, the safe and efficient transport of hydrocarbons from production sites to refineries and distribution centers is critical. Steel line pipes have become the material of choice for transporting oil and gas over vast distances, through challenging environments, and under extreme conditions. This blog delves into the reasons why steel line pipes are widely used for this purpose, exploring their key properties, advantages, and how they meet the demanding requirements of the oil and gas sector.

1. Introduction to Steel Line Pipes

Steel line pipes are cylindrical tubes made from carbon steel or other alloyed steels, specifically designed for transporting oil, natural gas, and other fluids in long-distance pipelines. These pipes must endure high pressures, extreme temperatures, and corrosive environments, making steel the ideal material for such applications.

Types of Steel Line Pipes:

  • Carbon Steel Line Pipes: Commonly used due to their strength, durability, and cost-effectiveness.
  • Alloy Steel Line Pipes: Used in more demanding environments, with added alloys like chromium or molybdenum for enhanced performance.
  • Stainless Steel Line Pipes: Offer excellent corrosion resistance, particularly in harsh environments.

2. Why Steel Line Pipes Are Preferred for Oil and Gas Transportation

Steel line pipes have several advantages that make them ideal for transporting oil and gas. Below are the primary reasons why the industry relies on steel for pipeline infrastructure.

2.1. Strength and Durability

Steel has unmatched strength and durability compared to alternative materials. Oil and gas pipelines need to withstand high internal pressures as well as external environmental factors such as soil movement, heavy loads, and even seismic activity. Steel’s high tensile strength ensures that the pipes can endure these forces without cracking, bursting, or deforming.

2.2. Corrosion Resistance

Oil and gas are often transported through corrosive environments, such as salty coastal regions, offshore platforms, or pipelines buried underground where moisture and chemicals can accelerate corrosion. Steel line pipes are manufactured with protective coatings like 3LPE (Three-Layer Polyethylene) or Fusion Bonded Epoxy (FBE) to enhance corrosion resistance. Alloyed and stainless steels provide intrinsic protection in highly corrosive environments.

2.3. High Temperature and Pressure Resistance

Pipelines carrying oil and gas frequently operate at elevated temperatures and pressures, especially in deep-water or underground pipelines where conditions are extreme. Steel has a high melting point and excellent heat resistance, enabling it to handle the high-pressure and high-temperature conditions without compromising structural integrity.

2.4. Cost Efficiency

While steel may not always be the cheapest material, it offers excellent lifecycle cost benefits. Steel line pipes are known for their longevity, reducing the need for frequent repairs and replacements. Additionally, the strength of steel enables manufacturers to produce thinner pipes with the same pressure rating, reducing material costs without sacrificing performance.

2.5. Ease of Fabrication and Installation

Steel is relatively easy to fabricate, allowing manufacturers to produce pipes in a wide range of sizes, lengths, and wall thicknesses to meet project-specific requirements. Steel pipes can be welded, rolled, or bent to fit complex pipeline routes, and can be produced in large quantities, making them highly adaptable for both onshore and offshore installations.

2.6. Leak Prevention and Safety

Steel pipes, especially those manufactured to stringent industry standards (such as API 5L for oil and gas pipelines), have superior resistance to leakage. The seamless or high-quality welded construction of steel line pipes minimizes weak points where leaks could occur. In addition, steel pipes can withstand harsh environmental conditions and mechanical damage, which reduces the likelihood of accidental spills or explosions.

3. Key Concerns Addressed by Steel Line Pipes

The oil and gas industry has several specific concerns regarding pipeline infrastructure, many of which are effectively addressed by using steel line pipes.

3.1. Corrosion Management

One of the most significant challenges for pipelines, particularly those buried underground or used offshore, is corrosion. Even though the external environment may be highly corrosive, the internal fluids, such as sour gas (H2S-rich natural gas), can also corrode pipelines. Steel line pipes combat this with advanced coatings, cathodic protection systems, and by using alloyed steels that resist chemical reactions, ensuring long-term protection and reliability.

3.2. Environmental Impact and Regulations

Environmental concerns, such as oil spills and gas leaks, can have devastating effects on ecosystems. Steel line pipes meet stringent environmental regulations due to their strength, durability, and ability to prevent leaks. These pipelines are often subjected to rigorous testing, including hydrostatic and X-ray tests, to ensure structural integrity. Many steel pipe systems also include real-time monitoring for early detection of leaks, helping mitigate environmental risks.

3.3. Operational Efficiency and Maintenance

Steel’s durability and ability to resist both external and internal forces minimize downtime and maintenance needs. With pipelines often spanning hundreds of miles, frequent repairs are impractical. Steel line pipes require less frequent maintenance and have a longer lifespan than other materials, providing higher operational efficiency and lower long-term costs for pipeline operators.

4. Steel Line Pipes and Industry Standards

The oil and gas industry is heavily regulated to ensure the safety, reliability, and environmental protection of pipeline systems. Steel line pipes are manufactured according to various standards to meet these stringent requirements.

Key Standards:

  • API 5L: Governs the manufacturing of steel line pipes for oil and natural gas transportation. It specifies material grades, sizes, and testing requirements to ensure the pipes can handle the pressures and environmental conditions of oil and gas pipelines.
  • ISO 3183: An international standard that outlines similar specifications as API 5L but focuses on pipeline materials and coatings for global applications.
  • ASTM A106: A standard for seamless carbon steel pipes used in high-temperature services, particularly in refineries and processing plants.

Adhering to these standards ensures that steel line pipes perform safely and effectively in the most demanding applications.

5. Advantages of Steel Line Pipes Over Alternative Materials

While other materials like polyethylene, PVC, or composite pipes may be used in low-pressure or small-diameter pipelines, steel remains the superior choice for large-scale oil and gas transport. Here’s why:

  • Higher Pressure Tolerance: Alternative materials typically cannot withstand the same high pressures as steel, making them unsuitable for long-distance transport of oil and gas.
  • Greater Temperature Resistance: Steel’s ability to endure extreme temperatures is unmatched by plastic or composite materials, which may become brittle or deform.
  • Longer Lifespan: Steel line pipes have an extended service life, often exceeding 50 years when properly maintained, while alternative materials may degrade more rapidly.
  • Recyclability: Steel is fully recyclable, which aligns with industry efforts to reduce environmental impact and promote sustainability.

6. Conclusion

Steel line pipes are indispensable in the oil and gas industry due to their exceptional strength, durability, corrosion resistance, and ability to withstand high-pressure and high-temperature environments. From the challenges of transporting oil and gas across vast distances to meeting stringent environmental and safety standards, steel line pipes have proven themselves as the most reliable and efficient option for pipeline infrastructure.

By choosing steel line pipes, oil and gas companies can achieve safer, more cost-effective, and long-lasting pipeline systems, ensuring the secure transportation of vital resources across the globe. The resilience and adaptability of steel continue to make it the material of choice for the industry’s ever-evolving needs.

What kind of pipe is Line Pipe ?

The Definition of Line Pipe

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In industries where fluids like oil, gas, and water need to be transported over long distances, the choice of piping systems is critical to ensure safety, efficiency, and cost-effectiveness. One of the most commonly used components in these sectors is line pipe. This blog post provides a detailed look into what line pipe is, its key features, applications, and considerations for professionals working in the transmission of oil, gas, and water.

What is Line Pipe?

Line pipe is a type of steel pipe that is specifically designed for the transportation of liquids, gases, and sometimes solids. Typically manufactured from carbon or alloy steel, line pipe is engineered to withstand high pressure, corrosion, and extreme temperatures, making it ideal for industries such as oil and gas, where fluids need to be transported over vast distances.

Line pipe plays a pivotal role in pipelines that move oil, natural gas, water, and other fluids from production facilities to refineries, processing plants, or distribution networks. It serves as the backbone of energy infrastructure, ensuring that raw materials are efficiently and safely delivered.

Key Features of Line Pipe

Line pipes are manufactured to meet strict standards and are available in various grades, dimensions, and materials to suit the needs of specific transmission systems. Here are some critical features that make line pipe an essential component for fluid transport:

1. Material Strength and Durability

Line pipe is primarily made from carbon steel, but other alloys such as stainless steel and high-strength, low-alloy steel may be used depending on the application. These materials offer excellent tensile strength, allowing the pipe to withstand high internal pressures and the mechanical stresses of installation and operation.

2. Corrosion Resistance

Corrosion is a significant concern in pipelines, especially those transporting oil, gas, or water over long distances. Line pipes often undergo various coating and treatment processes, such as galvanization, epoxy coatings, or cathodic protection systems, to resist corrosion and extend their operational lifespan.

3. High Pressure and Temperature Tolerance

Line pipes are designed to operate under high-pressure conditions. Depending on the fluid being transported and the environmental conditions, the pipe must tolerate significant fluctuations in temperature. Pipeline grades, such as API 5L, specify performance standards for different pressures and temperatures.

4. Weldability

Since pipelines are typically constructed in sections and welded together, line pipe must possess good weldability characteristics. Weldability ensures a secure, leak-proof connection between sections of pipe, contributing to the overall integrity of the pipeline.

Types of Line Pipe

Line pipes come in several types, each suited to specific needs. Here are the two primary types used in oil, gas, and water transmission:

1. Seamless Line Pipe

Seamless line pipe is manufactured without a seam, making it ideal for high-pressure applications. It is produced by rolling solid steel into a tube form and then extruding it to the desired thickness and diameter. Seamless line pipe offers higher strength and better resistance to corrosion and stress cracking.

2. Welded Line Pipe

Welded line pipe is made by forming flat steel into a cylindrical shape and welding the edges together. Welded pipe can be produced in large diameters, making it more cost-effective for low- to medium-pressure applications. However, welded pipe is more susceptible to stress at the seam, so it is often used where operating pressures are lower.

Common Applications of Line Pipe

Line pipe is used in a wide range of industries, including:

1. Oil Transmission

In the oil industry, line pipe is used to transport crude oil from extraction sites to refineries. The pipe must withstand high pressure, corrosive materials, and abrasive conditions, ensuring safe and continuous transportation over long distances.

2. Natural Gas Transmission

Natural gas pipelines require line pipe that can handle high pressures and remain leak-proof under fluctuating environmental conditions. Line pipes in natural gas applications also undergo additional testing for toughness and resistance to brittle fracture, especially in colder climates.

3. Water Distribution

Line pipes are extensively used for the distribution of potable water, wastewater, and industrial water. In water transmission, corrosion resistance is a major concern, and coatings or linings, such as cement mortar or polyethylene, are often applied to protect the steel and extend the pipe’s lifespan.

4. Chemical Transmission

Pipelines in the chemical industry transport a variety of liquids and gases, some of which may be corrosive or hazardous. Line pipe used in these applications must meet stringent safety standards to ensure there are no leaks or failures that could lead to environmental damage or safety hazards.

Key Standards for Line Pipe

Line pipes used in the oil, gas, and water transmission industries are subject to various international standards, which ensure that the pipes meet the necessary safety, performance, and quality requirements. Some of the most widely recognized standards include:

  • API 5L (American Petroleum Institute): This is the most commonly referenced standard for line pipes used in oil and gas transmission. API 5L defines requirements for pipe material, mechanical properties, and testing methods.
  • ISO 3183 (International Organization for Standardization): This standard covers the specifications for steel line pipes for pipeline transportation systems in the petroleum and natural gas industries. ISO 3183 ensures that line pipes are manufactured according to global best practices.
  • ASME B31.8 (American Society of Mechanical Engineers): This standard focuses on gas transmission and distribution piping systems. It provides guidelines on the design, materials, construction, testing, and operation of pipelines.
  • EN 10208-2 (European Standard): This standard applies to steel pipes used in the transmission of flammable liquids or gases in European countries. It sets performance benchmarks for materials, dimensions, and testing.

Common Standard and Steel Grade

API 5L PSL1 

PSL1 Line Pipe Mechanical properties
Grade Yield strength  Rt0,5 Mpa(psi) Tensile strength Rm Mpa(psi) Elongation 50mm or 2in
A25/A25P ≥175(25400） ≥310(45000) Af
A ≥210(30500) ≥335(48600) Af
B ≥245(35500) ≥415(60200) Af
X42 ≥290(42100) ≥415(60200) Af
X46 ≥320(46400) ≥435(63100) Af
X52 ≥360(52200) ≥460(66700） Af
X56 ≥390(56600) ≥490(71100) Af
X60 ≥415(60200) ≥520(75400) Af
X65 ≥450(65300) ≥535(77600) Af
X70 ≥485(70300) ≥570(82700) Af

API 5L PSL2

PSL2 Line Pipe Mechanical properties
Grade Yield strength  Rt0,5 Mpa(psi) Tensile strength Rm Mpa(psi) Rt0,5/Rm Elongation 50mm or 2in
BR/BN/BQ 245(35500)-450(65300) 415(60200)-655(95000) ≤0.93 Af
X42R/X42N/X42Q 290(42100)-495(71800) ≥415(60200) ≤0.93 Af
X46N/X46Q 320(46400)-525(76100) 435(63100)-655(95000) ≤0.93 Af
X52N/X52Q 360(52200)-530(76900) 460(66700)-760(110200) ≤0.93 Af
X56N/X56Q 390(56600)-545(79000) 490(71100)-760(110200) ≤0.93 Af
X60N/X60Q 415(60200)-565(81900) 520(75400)-760(110200) ≤0.93 Af
X65Q 450(65300)-600(87000) 535(77600)-760(110200) ≤0.93 Af
X70Q 485(70300)-635(92100) 570(82700)-760(110200) ≤0.93 Af

Practical Considerations for Line Pipe Selection

When selecting line pipe for oil, gas, or water transmission, it is essential to consider several factors to ensure optimal performance and safety. Here are some key considerations:

1. Operating Pressure and Temperature

The pipe material and wall thickness must be chosen to handle the expected operating pressure and temperature of the fluid. Over-pressurization can lead to pipeline failure, while insufficient tolerance for high temperatures may result in weakening or deformation.

2. Corrosiveness of the Fluid

Corrosive fluids such as crude oil or certain chemicals may require specialized coatings or materials. Selecting a pipe with the appropriate corrosion resistance can significantly extend the pipeline’s service life.

3. Distance and Terrain

The length and location of the pipeline will impact the type of line pipe needed. For example, pipelines crossing mountainous regions or areas with extreme temperatures may need more durable, thicker pipes to handle the stress and environmental conditions.

4. Regulatory and Safety Compliance

Compliance with local, national, and international regulations is critical. Ensure that the line pipe meets the required standards for the region and industry in which it will be used. This is especially important in hazardous industries like oil and gas, where pipeline failures can have severe environmental and safety consequences.

Conclusion

Line pipe is a critical component in the oil, gas, and water transmission industries. Its strength, durability, and ability to withstand extreme conditions make it indispensable for transporting fluids over long distances. By understanding the different types of line pipe, their applications, and key considerations for selection, professionals in these fields can ensure the safe and efficient operation of pipelines.

Whether you are working in oil extraction, natural gas distribution, or water infrastructure, selecting the right line pipe is essential for maintaining the integrity of your transmission systems. Always prioritize quality, safety, and compliance with industry standards to optimize pipeline performance and prevent costly failures.

What is fusion bond epoxy /FBE coating for steel pipes?

Fusion Bonded Epoxy (FBE) Coated Line Pipe

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Anti-corrosive steel pipe refers to a steel pipe that is processed by anti-corrosive technology and can effectively prevent or slow down the corrosion phenomenon caused by chemical or electrochemical reactions in the process of transportation and use.
Anti-corrosion steel pipe is mainly used in domestic petroleum, chemical, natural gas, heat, sewage treatment, water sources, bridges, steel structures, and other pipeline engineering fields. Commonly used anti-corrosion coatings include 3PE coating, 3PP coating, FBE coating, polyurethane foam insulation coating, liquid epoxy coating, epoxy coal tar coating, etc.

What is fusion bonded epoxy (FBE) powder anti-corrosive coating?

Fusion-bonded epoxy (FBE) powder is a kind of solid material that is transported and dispersed by air as a carrier and applied on the surface of preheated steel products. Melting, leveling and curing form a uniform anti-corrosion coating, which is formed under high temperatures. The coating has the advantages of easy operation, no pollution, good impact, bending resistance, and high-temperature resistance. Epoxy powder is a thermosetting, non-toxic coating, which forms a high molecular weight cross-linked structure coating after curing. It has excellent chemical anti-corrosion properties and high mechanical properties, especially the best wear resistance and adhesion. It is a high-quality anti-corrosion coating for underground steel pipelines.

Classification of fused epoxy powder coatings:

1) according to the use method, it can be divided into: FBE coating inside the pipe, FBE coating outside the pipe, and FBE coating inside and outside the pipe. The outer FBE coating is divided into single-layer FBE coating and double-layer FBE coating(DPS coating).
2)According to the usage, it can be divided into: FBE coating for oil and natural gas pipelines, FBE coating for drinking water pipelines, FBE coating for fire fighting pipelines, coating for anti-static ventilation pipelines in coal mines, FBE coating for chemical pipelines, FBE coating for oil drill pipes, FBE coating for pipe fittings, etc.
3) according to curing conditions, it can be divided into two types: fast curing and ordinary curing. The curing condition of fast curing powder is generally 230℃/0.5~2min, which is mainly used for external spraying or three-layer anti-corrosion structure. Due to the short curing time and high production efficiency, it is suitable for assembly line operation. The curing condition of ordinary curing powder is generally more than 230℃/5min. Due to the long curing time and the good leveling of the coating, it is suitable for in-pipe spraying.

Thickness of FBE coating

300-500um

Thickness of DPS(double layer FBE) coating

450-1000um

standard of coating

SY/T0315,CAN/CSA Z245.20,

AWWA C213,Q/CNPC38,etc

Use

Land and underwater pipeline anticorrosion

Advantages

Excellent adhesive strength

High insulation resistance

Anti-aging

Anti-cathode stripping

Anti high temperature

Resistance to bacteria

Small cathode protection current (only1-5uA/m2)

 

Appearance

 Performance index Test method
Thermal characteristics Surface smooth, color uniform, no bubbles, cracks and holidays                                                       Visual inspection

24h or 48h cathodic disbondment (mm)

 ≤6.5

SY/T0315-2005

Thermal characteristics(rating of)

1-4

Cross-section porosity (rating of)

 1-4
3 degree centigrade flexibility(Order specified minimum temperature+3 degree centigrade

No track

1.5J impact resistance(-30 degree centigrade)

 No holiday
24h Adhesion(rating of)

1-3

Breakdown voltage(MV/m)

 ≥30
Mass resistivity(Ωm)

≥1*1013

Anti-corrosion method of fusion bonded epoxy powder:

The main methods are electrostatic spraying, thermal spraying, suction, fluidized bed, rolling coating, etc. Generally, friction electrostatic spraying method, suction method, or thermal spraying method are used for coating in the pipeline. These several coating methods have a common characteristic, that is needed before spraying the workpiece preheated to a certain temperature, melt powder a contact namely, heat should be able to make the film continue to flow, further flow flat covers the whole surface of the steel tube, especially in the cavity on the surface of the steel tube, and on both sides of weld molten coating into the bridge, combined closely with the coating and the steel tube, minimize pores, and curing within the prescribed time, the last water cooling solidification process termination.

Introduction of 3LPE Coated Line Pipe

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Brief introduction:

The base material of 3PE anti-corrosive coating steel pipe includes seamless steel pipe, spiral welded steel pipe and straight seam welded steel pipe. Three-layer polyethylene (3PE) anti-corrosive coating has been widely used in the oil pipeline industry for its good corrosion resistance, water vapor permeability resistance and mechanical properties. 3PE anti-corrosion coating is very important for the service life of buried pipelines. Some pipelines of the same material are buried in the ground for decades without corrosion, and some are leaked in a few years. The reason is that they use different coatings.

Anti-corrosion structure:

3PE anti-corrosion coating is generally composed of three layers of structure: the first layer is epoxy powder (FBE) > 100um, the second layer is adhesive (AD) 170 ~ 250um, the third layer is polyethylene (PE) 1.8-3.7mm. In the actual operation, the three materials are mixed and integrated, which are processed to be firmly combined with the steel pipe to form an excellent anti-corrosive coating. The processing method is generally divided into two types: winding type and circular mold covering type.

3PE anti-corrosive steel pipe coating (three-layer polyethylene anti-corrosive coating) is a new anti-corrosive steel pipe coating produced by an ingenious combination of 2PE anti-corrosive coating in Europe and FBE coating widely used in North America. It has been recognized and used for more than ten years in the world.

The first layer of 3PE anti-corrosive steel pipe is epoxy powder anti-corrosive coating, and the middle layer is copolymerized adhesive with a branch structure functional group. The surface layer is high-density polyethylene anti-corrosive coating.

3LPE anti-corrosive coating combines the high impermeability and mechanical properties of epoxy resin and polyethylene. Up to now, it has been recognized as the best anti-corrosive coating with the best effect and performance in the world, which has been applied in many projects.

Advantages:

The common steel pipe will be severely corroded in the bad use environment, which will reduce the service life of the steel pipe. The service life of the anti-corrosion and heat preservation steel pipe is also relatively long. Generally, it can be used for about 30-50 years, and the correct installation and use can also reduce the maintenance cost of the pipe network. The anti-corrosion and heat preservation steel pipe can also be equipped with an alarm system, Automatic detection of pipe network leakage fault, accurate knowledge of fault location, and also automatic alarm.

3PE anti-corrosion and heat preservation steel pipes have good heat preservation performance, and the heat loss is only 25% of that of traditional pipes. Long-term operation can save a lot of resources, significantly reduce energy costs, and still have strong water-proof and corrosion-resistant ability. Moreover, it can be directly buried underground or in the water without an additional pipe trench, which is also simple, rapid, and comprehensive in construction. The cost is also relatively low, and it has good corrosion resistance and impact resistance under low-temperature conditions, and it can also be directly buried in frozen soil.

Application:

For 3PE anti-corrosion steel pipe, many people only know one thing and don’t know the other. Its function is really wide coverage. It is suitable for underground water supply and drainage, underground shotcreting, positive and negative pressure ventilation, gas drainage, fire sprinklers and other pipe networks. Waste residue and return water transmission pipeline for process water of thermal power plant. It has excellent applicability for the water supply pipeline of anti-spray and sprinkler systems. Power, communication, highway and other cable protection sleeve. It is suitable for high-rise building water supply, heat supply networks, waterworks, gas transmission, buried water transmission and other pipelines. Petroleum pipeline, chemical and pharmaceutical industry, printing and dyeing industry, etc. Sewage treatment discharge pipe, sewage pipe and biological pool anti-corrosion engineering. It can be said that 3PE anti-corrosion steel pipe is indispensable in the current construction of agricultural irrigation pipes, deep well pipes, drainage pipes and other network applications, and it is believed that through the extension of science and technology, it will still have more brilliant achievements in the future.

If you need any kind of anti-corrosion coating steel pipes such as 3PE coating steel pipes, FBE coating steel pipes and 3PP coating steel pipes, etc. Please contact us!