Erw steel tube Outside diameter: 21.3 to 610mm (1/2-24 inch) ... 5L,API 5CT, ASTM A53, ASTM A252, AST. Erw steel tube ERW Steel Pipe Outside diameter: 21.3 to 610mm (1 ... ASTM A2STM A252, ASTM A500, BS1387 ERW Steel Pipe Grade: A, B, X42, X46, X52, X56, X60, X65 X70 PSL1X70 PSL1 ...