NF A49-721-1 3-Layer PE Coated Buried or Submerged Pipeline

NF A49-721-1 3-Layer PE Coated Buried or Submerged Pipeline

The NF A49-721-1 standard defines the requirements for 3-layer polyethylene (PE) coating systems applied to steel pipelines that are buried underground or submerged underwater, providing a comprehensive solution for corrosion protection and mechanical integrity. This standard ensures that pipelines used in critical applications, such as oil and gas transportation, water supply, wastewater management, and chemical conveyance, are equipped with a robust coating system designed to withstand harsh environmental conditions. The 3-layer system, consisting of a fusion-bonded epoxy (FBE) base, an adhesive layer, and a tough outer polyethylene layer, delivers exceptional resistance to corrosion, mechanical damage, and environmental stressors, thereby extending the service life and reliability of pipelines in both onshore and offshore settings. By adhering to NF A49-721-1, industries can ensure that their pipeline infrastructure meets stringent safety and performance standards, safeguarding both the environment and the operational integrity of essential services.

Specifications

Standard	NF A49-721-1 3-Layer PE 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	First Layer: Epoxy Primer Layer (Thickness: 50μm at any point); Second Layer: Adhesive Layer; Third Layer: High-density Polyethylene Layer
Packing	1. Both ends of the pipe are beveled to 30°+5°/-0° according to ASME B16.25. 2. For large-diameter pipes (OD≥NPS 8″), each pipe is equipped with 3 anti-collision ropes (3 locations) and 2 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 3 anti-collision ropes (3 locations), plastic covers at the ends of the pipes, and 2 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 +70℃; alkaline or sour service
Place of Origin	Made in China
MOQ	Depends on order quantity
Transportation	Railway, By Sea

Properties of Layer 3 Polyethylene

Property	Unit	Value	Standard
Density	g/cm³	<0.935 or ≥0.935	NFT51-062
Melt Flow Index	g/10 min	≤2 or ≤0.8	NFT51-016(1)

Specified minimum coating thickness at any point along the tube’s diameter for thickness grades 1, 2, or 3.

Tube Diameter (Dmm)	Thickness Grade 1 (mm)	Thickness Grade 2 (mm)	Thickness Grade 3 (mm)
D ≤ 114.3	1.2	1.8	2.5
114.3 < D ≤ 273	1.5	2.0	2.5
273 < D ≤ 508	2.0	2.2	3.0
508 < D ≤ 762	2.2	2.5	3.5
D > 762	2.2	3.0	3.5
Note:
If the coating is used on weld pipes, the thickness provided in Table 2 may be reduced by 10% at the weld seams.
Thickness testing should be performed according to the definitions provided in Appendix B.

3LPE Coating Production Process

Applications of NF A49-721-1 3-Layer PE Coated Buried or Submerged Pipeline

The NF A49-721-1 standard provides specifications for the 3-layer polyethylene (PE) coating used on buried and submerged pipelines, ensuring effective protection against corrosion and mechanical damage in challenging environments. The 3-layer PE coating system typically includes a fusion-bonded epoxy (FBE) layer, an adhesive layer, and an outer polyethylene layer, combining the chemical resistance and bonding strength of FBE with the toughness and mechanical protection of PE.

Key Applications:

1. Oil and Gas Transmission Pipelines
   • Onshore Pipelines: The 3-layer PE coating is extensively used in buried pipelines that transport crude oil, natural gas, and refined petroleum products across long distances. The coating’s robustness ensures that the pipelines withstand soil stress, moisture, and corrosive elements in the ground, providing long-term integrity and reliability.
   • Offshore Pipelines: For pipelines laid on the seabed or in shallow waters, the 3-layer PE coating offers protection against corrosive seawater, physical abrasion from seabed materials, and impact from external objects, such as anchors or fishing equipment. This makes it an essential choice for offshore oil and gas fields.
2. Water Supply and Wastewater Pipelines
   • Potable Water Pipelines: In potable water systems, pipelines coated with the 3-layer PE system are buried to protect the water from contamination while also protecting the pipeline from external corrosive agents in the soil. The coating’s non-toxic properties make it suitable for water intended for human consumption.
   • Wastewater and Sewage Pipelines: These pipelines are often exposed to aggressive substances in the transported waste. The 3-layer PE coating protects the steel pipeline from corrosion, thus extending the lifespan of sewage and wastewater infrastructure.
3. District Heating and Cooling Networks
   • Buried Pipelines in Urban and Industrial Areas: District heating and cooling systems, which transport hot water, steam, or chilled water, often require buried pipelines to deliver energy efficiently across a city or industrial complex. The 3-layer PE coating provides thermal insulation, corrosion protection, and mechanical durability, ensuring the reliability of these critical infrastructure systems.
4. Chemical and Petrochemical Transport Pipelines
   • Submerged Pipelines: In chemical and petrochemical industries, pipelines are sometimes submerged in harsh environments such as acidic or alkaline soils, or aggressive industrial waters. The 3-layer PE coating is chosen for its ability to resist chemical attacks and mechanical damage, which is vital for the safe transport of chemicals and other hazardous materials.
5. Mining Industry Pipelines
   • Slurry Transport: In the mining industry, pipelines are used to transport slurries, which are mixtures of water and fine solid particles. These pipelines are often buried or submerged, requiring robust protection against abrasion and corrosion. The 3-layer PE coating provides the necessary protection, ensuring the pipeline’s long-term operation under harsh conditions.
6. Utility and Service Pipelines
   • Subsurface Electrical and Communication Conduits: For subsurface pipelines that protect electrical cables or communication lines, the 3-layer PE coating provides an additional layer of protection against environmental factors such as moisture ingress, chemical attack, and mechanical stress. This application is crucial for maintaining the integrity of utility services in both urban and rural settings.