hammer union ASTM A105 FMC WECO Interchangable size 1", 2", 3", 4", 6", 8" NPT Thread Butt-weld Scoket weld Hammer Union Hammer Unions are suitable for standard and sour environment, ranging in size from 1’’to 12’’with cold working pressures from 1,000 psi to 20,000 psi. All unions have their own color signs for quick identification. The materials meet ASTM and AISI standards. Hammer Unions are ...