L360 Seamless Steel Pipe for Natural Gas, Using 3LPE for External Corrosion Protection

In the natural gas transportation sector, L360 seamless steel pipe, with its high strength and low-alloy properties, has become a key material for ensuring the safe and stable operation of steel pipelines. The addition of 3LPE for external corrosion protection further enhances its durability and reliability in harsh environments.

L360 seamless steel pipe is designed specifically for high-pressure transportation applications such as oil and natural gas. Its yield strength is no less than 360 MPa, and its tensile strength can reach 460-760 MPa, enabling it to withstand the forces of complex geological conditions. This steel pipe complies with GB/T9711PSL2 standards and is delivered through normalizing rolling or normalizing and tempering processes to ensure uniform material structure and stable performance. Its chemical composition is carefully formulated to maintain a carbon content of ≤0.24% and a manganese content of ≤1.4%. Microalloying elements such as vanadium and niobium are added to ensure strength while enhancing weldability and resistance to hydrogen-induced cracking, providing a safe foundation for natural gas transportation.

The outer 3LPE anti-corrosion layer utilizes a three-layer composite structure: a fusion-bonded epoxy (FBE) base layer provides excellent interfacial adhesion and chemical resistance; an adhesive middle layer ensures a tight bond between the epoxy and polyethylene layers; and an outer layer of high-density polyethylene (PE) with a thickness of 2.5-3.7mm, forming a dense mechanical barrier. This structure combines the chemical resistance of the epoxy coating with the impact resistance of polyethylene, ensuring the anti-corrosion layer remains stable in temperatures ranging from -60°C to 60°C, with a water absorption rate of less than 0.01%, effectively resisting soil stress, chemical corrosion, and mechanical damage.

The combination of L360 seamless steel pipe and 3LPE anti-corrosion technology has been widely used in key national projects such as the Shaanxi-Beijing Natural Gas Pipeline and the West-East Gas Pipeline. Practice has demonstrated that this anti-corrosion system can extend the life of buried steel pipelines to over 50 years, significantly reducing overall lifecycle costs. Its construction technology is mature and can be applied via either wrapping or round die wrapping. It provides a strong bond with the steel pipe and eliminates the risk of leaks.