... , GB, ASME, ANSI, DINGrade20G, A106B, A179B, A234B, A53B, API J55, API K55, API L80, API N80, API P110, Din2391 17 Cr3, Q195, Q235, ST37Thickness0.5 ... the same cross-sectional area of other non-round steel tube, it has light weight, high intensity, big anti-curved section ...