Patent ID: 8720855

Claim:
A valve assembly comprising: a housing having a passage formed therethrough; a valve ball comprising metal having a through hole and disposed in the housing, wherein the valve ball is rotatable between an open position that has the through hole substantially aligned with the passage and a closed position that has the through hole substantially misaligned with the passage; a first seat comprising metal having a first sealing surface and disposed in the housing adjacent to the valve ball; and a second seat comprising metal having a second sealing surface and disposed in the housing adjacent to the first seat such that the first sealing surface of the first seat is disposed adjacent to the second sealing surface of the second seat, wherein the first sealing surface of the first seat comprises a first arcuate surface and the second sealing surface of the second seat comprises a second arcuate surface, wherein the valve ball and the first seat form a first metal-to-metal seal therebetween and are mate lapped together, and wherein the first seat and the second seat form a second metal-to-metal seal therebetween and are mate lapped together.