Steel Pipes China DN900

LSAW steel pipe: straight seam butt joint, "rigid choice" for high-pressure scene

LSAW steel pipe is a single steel plate pressed into U-shape and O-shape by a press, and then welded into a straight seam steel pipe. The welding method is also mainly submerged arc welding. Huayang's LSAW production line is equipped with a 4000-ton hydraulic press, which can process steel plates with a thickness of 40mm and is suitable for high-pressure and thick-wall scenes. Unlike SSAW, the weld of LSAW is a straight line, which is distributed in the longitudinal direction of the steel pipe, so it has a natural advantage in axial pressure resistance. In 2023, a 15,000-ton DN800 LSAW steel pipe was produced for a high-pressure gathering and transportation project of Sinopec. The steel plate was made of Wugang X70, and the residual stress was eliminated by post-weld heat treatment. The tensile strength of the weld reached 570MPa, far exceeding the 520MPa required by the project. However, this process requires high steel plate width, and the production of DN800 steel pipe requires 820mm wide steel plate, so the raw material cost is relatively high, and the die needs to be readjusted when changing specifications, so the production flexibility is lower than that of SSAW.