Blocking valve

Claim 1

A high-pressure valve for isolating a portion of a fluid path, comprising: a two-part valve body formed in a first part with a passage connectable in said fluid path and provided between opposite sides of said passage with a valve seat, a bore defined by both parts of said body and aligned with said seat, and means for tightening said parts together; a guide sleeve received in said bore; a valve rod axially shiftable and guided in said sleeve for displacement toward and away from said seat; a valve member juxtaposed with and engageable with said seat at one end of said rod; a control piston in either one of said parts acting upon an opposite end of said rod and displaceable in a cylinder formed in said other part of said body said valve member having a cross section greater than the cross section of said rod; a bellows surrounding said rod and secured to said valve member at a face therof turned away from said seat at one end of said bellows while being retained fixedly with respect to said sleeve at another end of said bellows; a tubular element received in said body coaxially surrounding said body at least at an end thereof connected to said valve member and surrounding said bellows to form an abutment engaging said valve member in a retracted position thereof to stabilize same against forces applied to said valve member by fluid traversing said passage in said open position of said valve member wherein direct flow of fluid is permitted through said seat along said passage in said open position; and means including annular flanges braced against a stack of thermally insulating annular gaskets for sealing said parts of said body together and to said sleeve upon operation of said means for tightening while providing a thermal barrier along said sleeve.