A Non-Lubricated Plug Valve is a quarter-turn rotary valve designed for on-off and throttling applications without the need for lubrication. Unlike lubricated plug valves, these valves use a self-lubricating polymer sleeve, elastomeric seals, or metal-to-metal contact for smooth operation. They are preferred for applications requiring minimal maintenance, contamination-free performanc... https://www.freture.com/plug-valve-manufacturers/non-lubricated-plug-valve/