Abstract: In the stem set configuration for a double block and bleed plug valve, the improvement provides an operator which can be significantly shorter and more compact than conventional operators for such valves. The invention makes use of a novel nesting of the threading section whereby a conventional female thread is replaced by a nested male thread surrounded by the translation section. The translation section, in turn, houses the indication section inboard of the nested male threads thereby compacting three functions into one location. This design lends itself nicely to investment casting technology obviating conventional machine shop practices. The invention also combines by use of a long plug stem pin, the plug connection and L slot functions into one location. The input function still remains separate, however, combining ultimately all functions in only three discrete locations and what appears at this time to be the ultimate compacted or nested arrangement.

Abstract: An improved bleed system for a double block and bleed plug-type valve which employ a safety check valve which automatically shuts off bleed system flow upon ruptures or upon an inadvertently open manual bleed valve during normal plug valve operation. An integral component combines the safety check valve and other bleed system components in a unitary device which is especially resistant to plumbing damage incidents.

Abstract: A unified block integral bleed system for use with valves such as plug-type valves wherein pressure release flow occurs through a manifold port mounting arrangement which accesses upstream, downstream and body cavity portions of the valve and provides atmosphere taps as well without external piping. Such a manifold integral body bleed system provides internal flow channels and is preferrably configured as a separate external unit which can be retrofitted to existing valve installations in the field. The manifold bleed system may be attached to the valve, such as by welding, or may be located at a position remote from the valve.