Abstract: A design for a ball valve seat uses elastomer and a hard material such as graphite or plastic to seal both high and low pressures. The seat is ring shaped. The seal is positioned on one end. In one embodiment, a rubber O-ring is installed in an outer groove, a plastic ring is installed in the inner groove. In another embodiment, the rubber is chemically heat bonded on the outside diameter of the plastic ring. The combination insert is installed in a single groove. Under low pressure, the rubber ring is compressed by a backing spring and urged against the ball to complete the seal. At higher pressures, the rubber ring is compressed more until the plastic ring contacts the ball. By the time the pressure reaches the initial plastic sealing pressure (below 1000 psig by design) the pressure between rubber ring and plastic ring will be the initial plastic sealing pressure. The low pressure zone will remain low pressure even when the upstream pressure is further increased.