API 5L standard specification provides standards for pipe suitable for use in conveying gas, water, and oil in the natural gas and oil industries. The API SPEC 5L covers seamless and welded steel line pipe.API 5L standard includes plain-end, threaded-end, and belled-end pipe, as well as through-the-flowline (TFL) pipe, and pipe with ends prepared for use with special couplings.API 5L standard main steel grade:X70,X65,X60,X56,X52,X46,X42,Grade A,Grade B and so on.