ASTM A53 is a carbon steel alloy that can be used as structural steel or for low pressure piping. ASTM A53 (ASME SA53) carbon steel pipe is a specification covering seamless, welded black and hot-dip galvanized steel pipe from NPS 1/8 "to NPS 26. A53 is suitable for pressure and mechanical applications, as well as for general use in steam, water, gas and air lines.

The A53 pipe has three types (F, E, S) and two grades (A, B).
Type A53F manufactured with furnace butt welds or may have continuous welds (Class A only)
Type A53E with resistance welds (Class A and B)
Type A53S is seamless and is found in Class A and B