API SPEC 5 l - 2011 (line pipe specification), is the American petroleum institute, compile and publish, common all over the world. Line pipe, is to take out oil, gas or water on the ground, through the pipeline ductules into oil and gas industry enterprises. Line pipe including both seamless and welded pipe, the pipe end with flat end, threaded end and socket end; Its connection way as the end of welding, coupling connection, socket connection, etc. The main material for B, X42, X46, X56, X65 and X70 steel grade