PLUG VALVE CONSTRUCTION

摘要

An improved plug valve of the type which includes a valve body having a bore extending therethrough and a pair of passages intersecting the bore and being substantially normal to an axis of the bore is disclosed. A valve plug is disposed within the bore for selective rotation between an opened and a closed position to respectively align and misalign a port through the plug with the passages. First circumferential sealing means is disposed between the plug and the bore above the port and the passages. A second circumferential means is located between the plug and the bore below the port and the passages to prevent fluid from escaping from an interior of the plug valve and to balance fluid pressure acting on the plug. The improvement according to the invention resides in a bottom insert snuggly fitted within said bore below said plug to enclose a base of said plug within said body. The bottom insert includes means for limiting said fluid pressure acting on said base of said plug if said second sealing means should fail by allowing escape of said fluid to the exterior of said body from said bore below said plug.