ASTM A53 is a carbon steel alloy, which can be used as structural steel or for low-pressure pipelines. ASTM A53 (ASME SA53) carbon steel pipe is a specification that covers seamless and welded black and hot-dipped galvanized steel pipe in NPS 1/8″ to NPS 26. A53 is intended for pressure and mechanical applications and is also acceptable for ordinary uses in steam, water, gas, and air lines. A53 pipe comes in three types (F, E, S) and two grades (A, B). A53 Type F is manufactured with a furnace butt weld or may have a continuous weld (Grade A only) A53 Type E has an electric resistance weld (Grades A and B) A53 Type S is a seamless pipe and found in Grades A and B)