Deformation problem of the valve PTFE lining
Thread Content
The DN80 stainless steel pneumatic ball valve installed on the steam pipeline started leaking steam after being in use for a short time. Upon inspection, it was found that the PTFE lining on one end of the valve (the inlet side) was severely deformed, while the other end was in good condition with no such issues visible. The valve was opened and closed more than twenty times per day, and all 3 valves in the system had this problem; several replacement valves were tried, but the issue persisted. I would appreciate it if someone with experience could tell me what the cause might be. The steam pressure is around 5 kilograms; once the valve is opened, the pressure drops to less than 1 kilogram.
You shouldn’t use those lined with fluoropolymer material, as they expand and deform; use a hard-sealed ball valve or a globe valve instead
The PTFE bushing mentioned by the poster is likely the sealing ring of the ball valve; deformation indicates a problem with the sealing ring, and the operating temperature is not sufficient. Try an integrated high-temperature resistant ball valve, or you can also choose a globe valve
It is best to use ball valves with metal seals, or enhanced PTFE. Otherwise, ordinary PTFE is not very suitable for use with steam.
For steam, when the temperature is below 200 degrees, PPL (carbon fiber) can be used as the sealing material, and its sealing performance is better than that of hard seals. It also has a long service life.
Ball valves should not be used on steam pipelines, let alone ball valves with soft seals. Gate valves should be used for the upstream valves on steam pipelines, while globe valves should be used for automatic control. Because both use hard sealing, and their coefficient of thermal expansion is also relatively low.
In high-temperature environments, the valve internals have hard seals on both sides.
The temperature is too high; it’s likely the seal ring that has deformed. For steam, globe valves or hard-sealed butterfly valves and ball valves are sufficient
The operating temperature of PTFE under no load is 190 degrees to 260 degrees; recommendations for use under load are provided
For this type of operating condition, gate valves or globe valves are the appropriate choice.