... and line connections, suction service, and corrosion service. Features O-ring in male sub improves sealing and protects metal-to-metal ... seal against corrosion; Replaceable O-ring extends union service life. 4, Figure 400 Hammer Union ... Parts: Detachable Nut, Male Sub, Female Sub, Seal Ring, Retainer Segment, Retainer Ring; Sour Service Models to NACE MR-01-75. ...