The products of the co***ny: American standard (size: a quarter-48) seamless steel tube, spiral pipe, tube and corrosion resistance welding steel tube; American standard elbow, the three links, flange, different-diameter pipe, tube cap, elbow pipe, etc. Execution standard API 5 L Gr. B/ASTM A106 Gr. B/ASTM A53 Gr. B/ASTM A333 Gr. 6 / ASME A234 WPB/ASME B16.5