LSAW Pipe vs SSAW Pipe

1. Advantages of LSAW steel pipe:

(1) LSAW steel pipe manufacturing using the tube expansion process residual stress is close to zero without the "Bauschinger" effect.

SSAW steel pipe due to the existence of molding stress in the manufacturing, resulting in the occurrence of the "Bauschinger" effect, it is necessary to use the steel to improve the production of a strength level, for example, with the X07 steel to produce X56 welded pipe. In addition, the existence of welding stress will lead to pipeline stress corrosion. China's more than 8000 kilometers of SSAW in the use of twenty years, due to the occurrence of stress corrosion and the destruction of the accident up to l ~ 2 times / year.

(2) LSAW steel pipe weld length is much shorter than the SSAW steel pipe weld length, so the incidence of weld defects is lower.

(3) LSAW steel pipe non-destructive testing is more convenient than SSAW steel pipe, online inspection is easier. In the welding quality, straight-seam submerged fox weld is easier to control than the oblique seam submerged fox weld.

(4) LSAW steel pipe molding quality is high, while SSAW steel pipe due to molding and welding at the same time is prone to hard corners, biting edges, inside and outside the weld is not equal to the problem.

(5) LSAW steel pipe heat-affected zone is smaller than the SSAW steel pipe and the heat-affected zone is the weak link in the quality of welded pipe.

(6) SLAW steel pipe can produce thick-walled steel pipe for ultra-high-pressure pipelines. For example, X07 steel, SSWA can produce wall thickness of 12-17 mm steel pipe and LSAW can produce wall thickness of 25 m m steel pipe, and even under certain conditions can produce wall thickness of 25 mm steel pipe.

2. Advantages of SSAW steel pipe：

(1) Welded seams avoid the main stress direction

After the pipe is subjected to internal pressure, the main stress is in the annular direction; SSAW weld is at an angle of about 45 degrees to the axis, so it avoids the main stress direction. The LSAW weld is perpendicular to the ring direction, the main stress direction.

(2) steel plate rolling direction of the highest impact toughness, and vertical rolling direction of the lowest impact toughness, the difference between the two several times.LSAW welding is the direction of vertical rolling steel plate, and SSAW welding is staggered in the direction of vertical rolling. Therefore, the SSAW tube by the internal pressure of the impact toughness than the LSWA steel pipe is good.

(3 ) for the production enterprise SSAW steel pipe production investment is small, low cost, change the product specification is convenient, raw materials are easier to solve.