As early as 1926, the American Petroleum Institute (API) released the API 5L steel pipe standard, initially only including A25, A, B three steel grade
Note: 1972 API release U80, U100 standard, later changed to X80, X100
2000 years ago, around the world using X70, about 40%, X65, X60 are in the 30%, the small diameter of the finished oil pipeline a considerable number of X52 steel grade, and mostly for resistance welding straight pipe (ERW pipe).
At present our country in the oil pipeline commonly used pipe type spiral submerged arc welded pipe (SSAW), straight seam submerged arc welded pipe (LSAW), resistance welded pipe (ERW). When the diameter is less than 152mm, choose seamless steel pipe.
China at the end of 1960s to 70s, the rapid development of spiral welded pipe factory, crude oil pipelines, almost all of the spiral welded pipe, a kind of "west east" pipeline also use spiral welded steel pipe spiral welded pipe. The disadvantage is the large internal stress, poor precision, high probability of defects. According to expert analysis, the "walking on two legs" approach, is now on a spiral welded pipe factory actively carry out technological transformation, but also in promising; two is to develop our LSAW pipe industry.
ERW steel pipe has the characteristics of smooth surface, high precision, low price and so on. It has been widely used at home and abroad.
