What is a Plug Valve?

The Plug Valve is one of the oldest valve designs and is known for its longevity. These valves are often used in industrial, commercial, residential, oil and gas, water treatment, and chemical processing. It features a cylindrical or tapered plug with a through hole in the middle as the closure member. The valve is open when the hole is lined up with the flow bore. The plug is rotated 90° to close. There are two primary designs. A lubricated Plug Valve relies on a thin film of lubricant/sealant between the plug and the valve body to form the seal. More lubricant can be added if the valve is leaking or frozen. A sleeved or lined Plug Valve relies on a soft elastomeric lining that forms the seal against the plug. The lining on a lined Plug Valve is typically made from a soft material like PTFE. The primary advantages are low-pressure drop, leak-tight seal (basically zero leakage), and quick quarter-turn opening. The main disadvantage is higher torque to open and close on larger valves. Lubricated Plug Valves (AKA gas cock) are very common in the distribution of natural gas.