Lubricated Plug Valve Design:

Clearances and leakage avoidance are the chief considerations in plug valves. Several plug valves are of all metal construction. In those versions, the narrow gap around the plug can permit leakage. If the gap is reduced by sinking the taper plug deeper within the body and actuation torque climbs rapidly and galling could occur. To remedy that condition, a series of grooves around the body and plug port openings are supplied within grease prior to actuation. To Applying grease lubricates the plug motion and seals the gap between body and plug. The Grease injected within a fitting at the top of the stem travels down through a check valve in the passageway, a past the plug top to the grooves on the plug, and down to a well below the plug. The lubricant must be compatible along with the temperature and nature of the fluid. Whole manufacturers of lubricated plug valves have established a series of lubricants which are compatible along with a huge range of media.

Their recommendation should be followed as to that lubricant is best suited for the service. The most general fluids controlled through plug valves are gases and liquid hydrocarbons. A few water lines have these valves, gives which lubricant contamination is not a serious danger. Lubricated plug valves might be as large as 24 inches and have pressure capabilities up to 6000 psig. Steel or iron bodies are available. The plug could be cylindrical or tapered.