ASTM A53/BS 6323 carbon steel seamless pipe OD: HRS 2"-30", CDS 0.875"-18" WT: HRS 0. ... 0.035"-0.875" ASTM A 53 Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and SeamlessGB ... circular steel tubes for mechanical and general engineering purposes schedule 40 steel pipe