ASTM A53 is a carbon steel alloy, used for structural steel pipe. The alloy specifications are set by ASTM International, in specification ASTM A53/A53M. A53 pipe is suitable for structural or pressure applications.
A53 pipe comes in three types and two grades, A53 Type F, which is longitudinally furnace butt welded or continuous welded (Grade A only), A53 Type E, which is longitudinally electric resistance welded (Grades A and B), and A53 Type S, which is seamless pipe, produced by hot working, and possibly cold finishing, the steel (Grades A and B). ASTM A53, Type S is now currently an outdated specification and has been replaced by ASTM A106 specification for seamless carbon steel pipe.
This is a standard set by the standards organization ASTM International, a voluntary standards development organizations that sets technical standards for materials, products, systems, and services.