Abstract: The present invention pertains to a seat for a ball valve, the seat defining an axial bore along an inside surface of the seat. The seat inside surface is in contact with a fluid. At one end of the seat inside surface, the seat comprises a contact portion for contacting a ball. The contact portion comprises a metal-to-metal sealing surface, a thermoplastic seal and an elastomeric seal. The metal-to-metal sealing surface is disposed proximally to the inside surface, the elastomeric seal is disposed distally to the inside surface, and the thermoplastic seal is disposed therebetween, wherein the metal-to-metal sealing surface seals against the ball valve to seal fluid away from the thermoplastic and elastomeric seals.

Abstract: The resilient delta ring seal for use in a seat for a ball valve is held in the seat having an annular opening for receiving and holding the delta ring seal. An apex of the seal is pointed radially inward toward the ball valve and a base of the seal is orientated radially away from the ball valve. The seal base is wider than the apex. The seal is placed in the seat apposite an annular resin insert having a surface disposed toward the ball valve. The seal apex is truncated obliquely to define a substantially flat apical surface that extends beyond the opening toward the ball valve and terminates at the resin insert.

Abstract: The present invention is a resilient delta ring seal for use in a seat for a ball valve. The seat has an annular opening for receiving and holding the delta ring seal therein so that an apex of the seal is pointed radially inward toward the ball valve and a base of the seal is orientated radially away from the ball valve. The seal base is wider than the apex and the apex protrudes beyond the opening and toward the valve. The seal apex is truncated to level the apex while the seal still extends beyond the opening and toward the valve.