Venting valve for a steam decorticator

A venting valve for a pressure vessel, comprising a housing defining a valve chamber, and having an inlet passage extending into said chamber for venting gas, and an outlet passage extending from said chamber at an angle to said inlet passage, replaceable valve seat means in said chamber, a valve closure member movably mounted in said chamber out of contact with the inner walls of said chamber to engage said valve seat for closing the valve, said valve closure member being movable to a position to deflect gases from said inlet passage to said outlet passage, means normally biasing said valve to its open position, said valve chamber comprising respective valve chamber walls, said inlet passage extending through one wall of said valve chamber, said outlet passage extending at an angle to said inlet passage through another wall of said valve chamber, said valve seat means comprising a tubular valve seat removably mounted in said inlet passage, a spindle, sealing means extending through a wall of said valve chamber opposite said one wall and aligned with said inlet passage, said spindle passing through said sealing means in a sealed manner, said valve closure member being mounted on said spindle within said valve chamber and aligned with said valve seat, and means coupled to said spindle externally of said valve housing for selectively urging said valve closure member against said valve seat, said means for selectively urging said valve closure member comprising a cylinder, a piston slideably mounted in said cylinder, a piston rod connected to said piston and extending externally of said cylinder, and a pivoted lever coupling the external end of said piston rod to said spindle, said cylinder having a pressure inlet opening, whereby application of pressure to said pressure inlet opening effects movement of said piston, piston rod, lever and spindle to move said valve closure member against said valve seat within said chamber.