Soft seal installation for feed water check valve

Claim 1

In a swinging check valve having a valve portion swingable between an open and a closed position, the check valve including a valve body having an annular valve seat, said valve body and said valve portion having hard metal conical complementary facings adapted to form the primary valve seal when brought together, the improvement comprising a backup system including an annular flexible valve sealing element displaced outwardly from said primary valve seal on the valve portion to engage the annular valve seat on the valve body to close the valve, the valve portion including an annular groove extending about its circumference and having mounted therein said flexible annular valve sealing element, said element having a "U" shape when viewed in cross section, with a rounded outer surface adapted to contact said valve seat with the legs of the "U" in contact with the bottom and sides of annular groove and with the hollow interior of the "U" forming a chamber with the bottom of the groove constituting one side thereof and being cooperatively adjacent to the annular valve seat on the valve body when the swing check valve is in its closed position, a passage leading from said chamber to the opposite side of the valve portion whereby the chamber is in communication with fluid under pressure from within the valve body to expand the flexible sealing element outward into sealing engagement with the annular valve seat.