Ladies and Les (CWI graduate engineer),
Oil field tubular products are a different animal than API line pipe.
There is no X48. There is X42, X46, X52, X56, X60, X65, X70 & X80.
Those can be made to a schedule size or an API size. API size most often.
There is also multi grade baby size pipe made to A-53 grade B/API X42 (or API 5L gr. B). That's fairly common.
JT, not a CWI graduate engineer.