Study On The Applicability Of L360 Spiral Welded Steel Pipe Hot Bending Pipe

Bend is an important component in the pipeline of oil and gas,which can change the direction of the pipeline according to piping design requirement. Most of the mother tube of producing roasted bend is product with seamless steel tube or straight welded steel pipe in has been built or under construction of oil and gas transmission pipelines of china. Sometimes SSAW pipeline also can be applied to product bend, which was used in Zhongwu Gas pipeline.The SSAW pipeline which has the character of low cost and easy access will bring great convenience to engineering construction, if it is used as mother tube to making elbow. Because the performance of the steel tube will change in a certain extent, it is really necessary to carry out the applicability study of SSAW pipeline bend simmer in order to determine the applicability and manufacturing process of the bend.This paper adopts five kinds of outer diameter specifications L360 SSAW pipeline trial elbow to do experiments and develops the applicability research of the two kinds outer diameter specifications seamless steel pipe elbow. It also focuses on the weld properties of various parts of the spiral weld elbow and takes a design verification test to analyze the possibility of spiral weld elbow production and application, which can provide a reference for optimizing the production process effects and producing of SSAW heating bending pipeline.Tests show that the tensile properties and the toughness of SSAW pipeline roasted bend whose outer diameter specifications is D426 and above can reach the level of the parent tube. That can produce the elbow which mechanical properties are qualified. And its bending test is without cracking phenomenon. The smaller diameter D325 SSAW pipeline whose weld root bend specimens in inner arc and neutral zone back bend is cracking along the weld in the bending test. That shows that the pipe of that specimen is unsuitable for induction heating pipe bending. So it is suggested that the smaller diameter bend uses seamless steel pipe to bend and its recommended thickness to diameter ratio of mother pipe should be greater than 0.018, which can avoid appearing the "wrong side" phenomenon elbow inner arc weld.Through this research proposes the quality requirements of L360 SSAW Heating bending pipeline and L360 SSAW pipeline hot bending elbow manufacturing process, provides the reference for the actual production of L360 SSAW Heating bending pipeline.