Steel Pipes China

Mechanical strength: LSAW is the best, and ERW and SSAW have their own emphases

Huayang inspected three kinds of steel pipes with the same specification (DN300, wall thickness 10mm). The results showed that the tensile strength of LSAW steel pipe (X70 material) was 570-650MPa, and the yield strength was ≥ 485 MPa. SSAW steel pipe (Q345B material) has a tensile strength of 470-550MPa and a yield strength of ≥ 345 MPa; The tensile strength of ERW steel pipe (ASTM A53 Grade B) is 414-517MPa, and the yield strength is ≥241MPa. Obviously, LSAW has an absolute advantage in strength, which is also the core reason why it can be used for high-pressure oil and gas transportation. In the Sinopec project in 2023, LSAW steel pipe has no deformation under the test pressure of 1.8MPa, while ERW steel pipe under the same pressure has a slight radial expansion (≤0.1mm), which needs to be repaired by thermal straightening process.

But the advantage of ERW lies in weld toughness. Through the technology of "low temperature rapid welding+normalizing heat treatment", Huayang made the impact toughness of ERW weld reach 35J at -20℃, which was 17% higher than that of SSAW. In the winter water supply project in Harbin, the ERW steel pipe of Huayang has been in service for two years at the low temperature of -25℃, and there is no brittle crack in the weld, while the SSAW steel pipe of a manufacturer has three leaks due to the lack of toughness in the weld.