This document specifies the grade representation method, classification and code, ordering content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificates of carbon steel twin-roll cast-rolled thin steel strips for welded steel pipes Book. This document applies to carbon steel twin-roll cast-rolled thin steel strips (hereinafter referred to as thin steel strips) with a thickness of 0.6mm~2.0mm for welded steel pipes.