Patent ID: 6935616

Claim:
A balanced plug valve comprising a housing having fluid conducting inlet and outlet ports and an upper terminating surface, said housing having an essentially central, vertical bore incorporating a number of stepped diameter portions one of which straddles said inlet and outlet ports and forming a first seating surface and where a second stepped diameter provides for a second seating surface, a valve plug slidingly arranged within said vertical bore and having stepped diameter portions capable of engaging said first and second seating surfaces when in the lowest sliding position, a bonnet having a lower, flat terminating surface and being suitably fastened near the upper terminating surface of said housing and furthermore being capable of preventing fluid egress from said housing bore, and means to motivate said valve plug, a thin, flexible metal washer is placed under said flat, terminating surface of the bonnet, and having an internal diameter somewhat smaller than that of the adjacent housing bore, and being capable of forming said second seating surface.