Line Pipes are manufactured under regulations specified by API. the standard used worldwide in the manufacturing of line pipes is API Specification 5L. this specification defines that the pipeline will be used to transport crude oil, petroleum products, natural gas or water. the pipeline manufacturing industries produce two types of line pipes, i.e., seamless line pipe and welded line pipe.
Seamless line pipes are manufactured from a cylindrical bar of steel and are heated to very high temperatures. When the pipe becomes red hot, it is then pierced with a probe to create necessary holes into it. this red hot cylindrical bar is run through rollers to produce proper wall thickness and diameter.
Welded line pipe are widely used for interstate natural gas pipelines. these pipelines are generally large diameter pipelines produced by forming steel plate into cylindrical shape and seam is closed by welding process. The quality of the welded seam is checked by using ultrasonic or radiological inspection method and pressure test is performed at each joints.
Line pipes once manufactured undergo quality and inspection checks for steel chemistry, dimensional characteristics, strength and toughness.