US Patent 10443343 Threaded packing element spacer ring

An extrusion ring is attached at a mandrel end to a gage ring as well as a softer ring that is disposed between the extrusion ring and the mandrel. The softer ring acts as an extrusion barrier along the mandrel. On setting the softer ring protects a free end of an extrusion ring from contact with the sealing element by extending axially at least as far as the extrusion ring and preferably further. The sealing element being softer than the adjacent softer ring allows the extrusion ring to push the softer ring out past the end of the extrusion ring and allows the softer ring to fill a void space adjacent the free end of the extrusion ring and to the sealing element. Relative motion between the rings at the attachment location is prevented.