NF A49-721-1 3-Layer PP Coated Buried or Submerged Pipeline
- Applied Steel Service Pipe: API 5L/ISO 3183 Gr.B-X100, ASTM A53/A106 Gr.B, ASTM A333 Gr.1/3/6, ASTM A671/A672/A691
NF A49-721-1 3-Layer PP Coated Buried or Submerged Pipeline
The NF A49-721-1 standard provides a comprehensive framework for designing and applying 3-layer polypropylene (PP) coated pipelines intended for buried or submerged environments. This standard outlines the specifications for a robust coating system that combines a corrosion-resistant polypropylene layer with additional protective layers to ensure the longevity and integrity of pipelines exposed to harsh environmental conditions. By addressing factors such as coating adhesion, thickness, and resistance to physical and chemical degradation, NF A49-721-1 aims to enhance the performance and durability of pipelines in various industrial and infrastructural applications. This standard is essential for professionals seeking to implement advanced coating technologies that meet rigorous industry requirements for reliability and safety.
Specifications
| Standard | NF A49-721-1 3-Layer PP Coated Buried or Submerged Pipeline |
| Applied Steel Service Pipe | API 5L/ISO 3183 Gr.B-X100, ASTM A53/A106 Gr.B, ASTM A333 Gr.1/3/6, ASTM A671/A672/A691 |
| Processing ability | OD:38mm-1620mm; WT:2mm-30mm |
| Length | 6-18m |
| Surface Preparation | ISO 8501-1/SIS 055900/DIN 55928 Sa 2.5/NACE No.2/SPCC SP10 (Near White Metal Finish) |
| Coating Structure | The first Layer is the epoxy Primer Layer (Thickness: 50μm minimum); the Second Layer is the adhesive Layer (Thickness 150μm minimum); the Third Layer is the high-density Polypropylene Layer |
| Packing | 1. Both pipe ends are beveled to 30°+5°/-0° according to ASME B16.25. 2. For large-diameter pipes (OD≥NPS 8″), each pipe is equipped with three anti-collision ropes (3 locations) and two slings, with plastic covers at the ends of the pipes or reusable metal bevel protectors (with sealing cloth), loosely packed. 3. For small-diameter pipes (OD≤NPS 6″), each pipe is equipped with three anti-collision ropes (3 locations), plastic covers at the ends of the pipes, and two slings per bundle (the whole bundle can be wrapped in a woven bag according to the coating type or customer requirements) and tied with plastic strips (woven bags are placed underneath to protect the coating from scratches) |
| Technique | Coated on Seamless/ERW/HFW/LSAW/SSAW/JCOE/UOE/RBE Line Pipes |
| Service condition | Design working temperature ranges: -20℃ to +110℃; alkaline or sour service |
| Place of Origin | Made in China |
| MOQ | Depends on order quantity |
| Transportation | Railway, By Sea |
Properties of Layer 3 Polypropylene
| Property | Unit | Value | Standard |
| Density | g/cm³ | 0.895 / 0.905 | NF T 51-063 |
| Melt Index | g/10 min | 0.5 / 4.0 | NF T 51-016¹ |
| Note: | |||
| 1. Melt index measured at 230°C under a load of 2.16 kg, per condition 12 of the standard NF T 51-016. | |||
Minimum Coating Thickness
Depending on the thickness class (1 or 2) specified during ordering and based on the pipe diameter, the minimum coating thickness at any point on the pipeline shall correspond to the values provided in the Table below:
| Tube Diameter D (in mm) | Thickness Class 1 (in mm) | Thickness Class 2 (in mm) |
| D≤114.3 | 1.2 | 1.2 |
| 114.3 < D≤273 | 1.2 | 1.5 |
| 273 < D≤508 | 1.2 | 1.8 |
| 508 < D≤762 | 1.5 | 2.0 |
| 762≤D | 1.7 | 2.5 |
| Notes: | ||
| 1. For thicknesses starting from 1.8 mm, the thickness in Table 3 can be reduced by 10% for welded tubes at the weld reinforcement. | ||
| 2. the Purchaser and the Coater can agree on different thicknesses. | ||
| 3. The thickness check should be conducted by the criteria defined in Annex B. | ||
3LPE Coating Production Process
Applications of NF A49-721-1 3-Layer PP Coated Buried or Submerged Pipeline
The NF A49-721-1 standard covers the specifications for 3-layer polypropylene (PP) coating systems applied to steel pipelines, primarily used in harsh environments where superior mechanical protection and corrosion resistance are essential. This coating is particularly suitable for:
- Offshore Pipelines: The 3-layer PP coating provides excellent resistance to seawater’s mechanical stresses and corrosive effects, making it ideal for pipelines laid on the seabed in deepwater and shallow-water oil and gas projects.
- High-Temperature Applications: Polypropylene’s high melting point makes it suitable for pipelines that operate at elevated temperatures, which is common in transporting crude oil and hot gases.
- Buried Pipelines: In onshore applications, the 3-layer PP coating protects against soil stress, moisture, and corrosive elements, ensuring the long-term integrity of pipelines transporting oil, gas, water, and chemicals.
- Hydropower and Dam Conduits: The coating is also effective for pipelines submerged in freshwater environments, such as those used in hydropower plants and dam outlets, where it provides robust protection against water pressure and mechanical damage.
- Chemical Transport Pipelines: In the chemical industry, where pipelines are exposed to aggressive substances, the 3-layer PP coating offers reliable protection against chemical corrosion, ensuring the safe and efficient transport of hazardous materials.
