{TAIL ~ Gate valve} having a secondary seal, wherein the gate forms a metal to metal seal with the seat and wherein a resilient seal is moved toward the gate when the gate is in {HEAD ~ closed position} to form a secondary fluid tight seal with the gate, whereby leakage past the gate is effectively prevented 
{ TAIL ~ Gate valve } having a secondary seal , wherein the gate forms a metal to metal seal with the seat and wherein a resilient seal is moved toward the gate when the gate is in { HEAD ~ closed position } to form a secondary fluid tight seal with the gate , whereby leakage past the gate is effectively prevented
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