API 5L specification covers seamless and welded steel line pipe. It includes standard-weight and extra-strong threaded line pipe. It includes standard-weight and extra-strong threaded line pipe; and standard-weight plain-end, regular-weight plain-end, special plain-end, extra-strong plain-end, special plain-end, extra-strong plain-end pipe; as as well as bell and spigot and through-the-flow line(TFL) pipe.API 5L also requires a