ASTM A53 Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless.ASTM A53 Standard specification covers seamless and welded black and hot-dipped galvanized steel pipe in NPS 1/8 to NPS 26.ASTM A53 standard main steel grade:A53 Grade A,A53 Grade B and so on.