Nonlubricated Plug Valves

The nonlubricated plug valve may be successfully used in refinery loading services in 2-inch, 3-inch, 4-inch sizes rated at 300 psi. The advantages of using this type of valve are bubble-tight closure, easy repair by replacing the slips and compact size with relatively quick opening action. 

The chief disadvantages are high costs (40% greater than steel gate valves) and low temperature limits of 180° F. 

This type of valve has given very good service in transfer and loading operations in 3-inch and 4-inch sizes. It has also been used satisfactorily in 4-inch and 6-inch sizes for vacuum truck service. Another example of its use is in catalytic-polymerization imit piping operating at 1,000 psig and 400° F. 

For high-temperature operation, the valves are supplied with 13% chrome plugs and seats as standard trim. Fluorinated plastic packing is used for service below 500°F. 

Pipeline Products. For bubble-tight positive segregation of products in pipelines, nonlubricated plug type valves have proven very satisfactory. This type of valve may be specified with plastic seat rings bonded to 14 to 36% nickel-iron alloy slips and a flag-type indicator on top to give definite open-closed identification. 

---