Significance of developing straight seam submerged arc welded pipe

At present, welded tubes are mainly used for long-distance oil and gas transportation, and the pipeline steel pipes used for long-distance pipelines mainly include spiral submerged arc welded steel pipes (SSAW pipes) and straight seam double-sided submerged arc welded steel pipes (LSAW pipes). Since the spiral submerged arc welded pipe is made of strip steel, the wall thickness is limited, and the improvement of steel grade is limited by the heat treatment of the material. In addition, the spiral submerged arc welded pipe has some shortcomings that are difficult to overcome, such as long weld seam, large residual stress, and poor weld seam reliability. As the requirements for octg pipe are getting higher and higher, it is no longer used in densely populated areas and areas with high reliability requirements, and large diameter longitudinal welded pipes are gradually replacing spiral welded pipes.

Recently, China is speeding up the development of oil and gas in the East China Sea, with the development of oil exploration to the depths of the ocean. Due to the influence of pressure, impact force and bending force, the pipeline laid on the seabed is also flattened, which is the weak link of the spiral welded pipe. In order to improve the transportation capacity of pipelines and ensure the development of submarine pipelines in the direction of thick walls, longitudinal seam welded pipes are mostly used in submarine pipelines. Therefore, compared with spiral welded pipes, straight seam welded pipes have higher dimensional accuracy and easier repair welding, so from this aspect, straight seam welded pipes are also the first choice.

Coal slurry ore slurry and slurry pipelines need to use straight seam welded pipes, and pipeline transportation is "paste" pipeline transportation is the upward direction. Since the weld reinforcement of the spiral welded pipe is a spiral line, the resistance to the coal slurry is large, and the pipe needs a larger wall thickness, so the straight seam welded pipe is tended to be used.

Longitudinal welded pipes are required in machinery, construction, chemical and other industries. At present, the valve seat in the machinery industry uses forgings to process the inner hole, which is labor-intensive, time-consuming, and material-consuming. If thick-walled straight seam welded pipes are used, it will be more economical. In addition, due to the mechanical performance requirements of anti-flattening, only straight seam welded pipes are used for construction pipes; straight seam welded pipes are also desired for chemical pipes.

Article source: https://article-realm.com/article/Finance/41942-Significance-of-developing-straight-seam-submerged-arc-welded-pipe.html