3LPE Coating Steel Pipes

What’s a 3LPE steel pipe?

The 3LPE coated steel pipes for an oil & gas project in Kuwait; Black color for external surface, bare surface of the interior, API 5L Gr.B PSL2.

A 3LPE coating steel pipe refers to a steel pipe that has been coated on its external surface with a protective coating system known as 3LPE, which stands for “three-layer polyethylene.” This coating system is applied to steel pipes to provide corrosion protection, particularly in environments where the pipes are exposed to moisture, chemicals, soils, wastewater, and other corrosive substances.

Steel pipes as the substrate

In general, 3LPE-coated steel pipes can be made from various types of base steel pipes, and the choice of base steel pipe type depends on specific engineering requirements and application scenarios. Here are some common types of base steel pipes and the standards they are produced according to:

• Welded Steel Pipe: Welded steel pipes are pipes formed by welding steel plates or strips together. Common types of welded steel pipes include longitudinal welded pipes and spiral welded pipes. Relevant standards for the production of welded steel pipes include API 5L, ASTM A53, AWWA C200, ASTM A252, DIN 2458, EN 10217, and EN 10219, etc.
• Seamless Steel Pipe: Seamless steel pipes are pipes without welded seams, offering higher strength and better sealing. Common types of seamless steel pipes include hot-rolled seamless pipes and cold-drawn seamless pipes. Relevant standards for the production of seamless steel pipes include API 5L, ASTM A106, ASTM A333, and DIN 1629, etc.

The 3LPE coating system

The illustration of the 3LPE coated steel pipe.

The 3LPE coating for a steel pipe consists of three layers:

• Fusion-Bonded Epoxy (FBE) Primer: This is the first layer applied directly to the external surface of the steel pipe. The FBE primer serves as a corrosion barrier, providing excellent adhesion to the steel substrate and preventing the formation of rust and corrosion.
• Adhesive Layer: The second layer is an adhesive copolymer that bonds the FBE primer to the outer polyethylene layer. This adhesive layer ensures strong adhesion between the primer and the polyethylene coating.
• Polyethylene Layer: The outermost layer is made of high-density polyethylene (HDPE) or low-density polyethylene (LDPE). This layer acts as the primary barrier against corrosion, providing a protective shield to the underlying layers and the steel substrate. Polyethylene is highly resistant to chemical attack, moisture, and environmental factors, helping to prevent corrosion of the steel pipe even in harsh conditions. It also provides mechanical protection to the underlying FBE primer and adhesive layer. The polyethylene coating also helps to minimize friction and resist abrasion during handling, installation, and operation of the pipe.

Benefits

The delivery of SSAW steel water pipes to a client in South Africa. Black 3LPE coated exterior, and white epoxy coated interior. Inland transportation by truck from the factory to Xingang Port, China.

3LPE coating steel pipes are suitable for a wide range of applications across various industries, including oil and gas transportation, water distribution, wastewater treatment, chemical processing, infrastructure development, and more.

• Corrosion Protection: The primary benefit of 3LPE coating is its excellent corrosion protection for steel pipes. The combination of the three layers forms a robust barrier against corrosive elements such as moisture, chemicals, and gases, significantly reducing the risk of rust and corrosion on the steel surface.
• Extended Service Life: By effectively preventing corrosion, 3LPE coating helps to extend the service life of steel pipes. Coated pipes can withstand exposure to harsh environments, including underground burial, marine applications, and chemical processing plants, without experiencing premature degradation or failure due to corrosion.
• Cost Savings: Investing in 3LPE-coated steel pipes can lead to long-term cost savings for infrastructure projects and industrial applications. The reduced need for maintenance, repair, and replacement of corroded pipes translates into lower operational costs and fewer disruptions to operations, resulting in overall cost efficiency over the lifecycle of the pipes.
• Mechanical Protection: In addition to corrosion resistance, 3LPE coating provides mechanical protection to the steel pipes. The polyethylene top layer acts as a barrier against physical damage, such as abrasion, impact, and handling during transportation and installation, helping to maintain the structural integrity of the pipes.
• Environmental Protection: 3LPE coating is environmentally friendly and compliant with regulatory standards for hazardous substances. The materials used in the coating system are non-toxic and inert, ensuring that the coated pipes do not leach harmful substances into the surrounding soil, water, or air, thereby minimizing environmental impact.