The pipe wall thickness grade is indicated by the pipe number

　　The pipe wall thickness grade is indicated by the pipe number, the common pipe number is Sch40 and Sch80. When selecting the API 5CT 2 3/8" L80 Seamless Casing pipe Coupling, the Coupling should be the same as the Coupling number of the Coupling to which it is connected, that is, the strength of pipe and pipe, Thick), except that the wall thickness of the end of the Coupling is the same as the wall thickness of the Coupling. China's National Standard for Steel Butt Welded Pipe Fittings Coupling (GB12459) and China Petroleum & Chemical Corporation Standard (SH3408) are basically the same as ASME B16.9, B16.28, JIS, JPI-7S and JPI-7S-1.