Patent ID: 8672295

Claim:
A gate valve, comprising: a valve body having an internal working fluid passage with a longitudinal axis and an internal gate chamber extending transverse to the working fluid passage; a gate disposed in the internal gate chamber and movable within the gate chamber between a closed position obstructing fluid flow through the working fluid passage and an open position allowing fluid flow through the working fluid passage; an internal sealing arrangement coaxially disposed in the working fluid passage and extending between the valve body and the gate to form a barrier between the internal working fluid passage and internal gate chamber; and an internal venting passage extending from the internal gate chamber to the internal working fluid passage for selective venting of fluid pressure from the internal gate chamber to the internal working fluid passage; a valve disposed in the internal venting passage, wherein the valve is configured to automatically vent fluid pressure from the internal gate chamber to the internal working fluid passage at a predetermined pressure differential between the internal gate chamber and the internal working fluid passage; wherein the internal sealing arrangement includes a frustoconical metal sealing surface adapted to sealingly engage an opposed mating frustoconical metal sealing surface on the valve body to form a first metal-to-metal seal between the sealing arrangement and the valve body; wherein the internal sealing arrangement further comprises a metal sealing surface adapted to sealingly engage an opposed mating metal sealing surface on the gate to form a second metal-to-metal seal between the sealing arrangement and the gate; wherein the internal sealing arrangement comprises a radially outer seat carrier and a radially inner valve seat in telescoping arrangement between the valve body and the gate.