LSAW Steel Pipe Offshore Oil Pipeline API 5L PSL1 X56Q-Z35

API 5L PSL1 X56Q-Z35 is designed for moderate-to-high pressure offshore transmission systems. The minimum yield strength reaches 390 MPa, with tensile strength between 490–630 MPa. The "Q" condition indicates quenched and tempered delivery, improving strength and toughness stability. Z35 certification ensures through-thickness reduction of area ≥35%, effectively mitigating lamellar tearing risks in welded offshore structures. Typical chemical limits include C ≤0.24%, Mn ≤1.40%, P ≤0.030%, and S ≤0.030%, balancing weldability and mechanical reliability.

Huayang manufactures these pipes using JCOE forming with double submerged arc welding, followed by 100% ultrasonic testing and hydrostatic pressure testing. For offshore service, external anti-corrosion systems such as 3LPE or FBE coatings can be applied to enhance long-term resistance against seawater and chloride exposure.