Painful butterfly valve
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Butterfly valves are widely used in large-diameter gas pipelines. Their sealing performance is acceptable at first use (when the gas temperature is around 200 degrees), but problems arise later on – the valves fail to close properly. Could those who design these valves explain why this happens?
Poster: A soft-seal type was chosen, right? It can be replaced with a metal-seal butterfly valve
What could be the reason why it can’t be shut off? I work with butterfly valves, and this phenomenon seems quite rare. Could you clarify whether the problem you’re facing is that the valve won’t close properly?
I think the main reason for this is the difference in materials between the valve seat and the valve core; due to these different materials, their degrees of thermal expansion and contraction vary That’s why this situation occurs! This is just my rough estimate! If it’s not you, you can explain the specific situation; we can discuss it! !
However, your temperature is indeed high enough; soft-sealed butterfly valves certainly won’t work (the high switching frequency and high temperature of the medium result in poor sealing performance of such valves). What was suggested above regarding the use of hard-sealed butterfly valves also won’t work – although it may help with the issue of medium temperature, the sealing problem remains unresolved and leakage will still occur. Using globe valves (of foreign origin) can completely solve this problem. QQ: 928976489 (Your control valve consultant)
Valves with soft seals may experience local deformation due to thermal expansion and contraction when the temperature reaches such high levels. This is my personal opinion. Therefore, it is recommended that you use a hard-sealed butterfly valve.
Let’s first find out what’s causing the problem before deciding on a solution. No issues have been identified; to be honest, the temperature, as mentioned by the original poster, isn’t that high either. Using a hard-sealed butterfly valve should be fine. If it doesn’t close properly, could it be that the positioning of the butterfly valve’s switch is inaccurate? It might help to adjust it and give it a try
A metal seal is necessary, as is an eccentric design; ideally, a triple-eccentric design.
That’s the lifespan of domestic low-end butterfly valves – they leak more as they are used longer. The poster can consult with professional domestic manufacturers of butterfly valves, such as Jiangnan Valves, Zhengzhou Butterfly Valves, Suzhou High and Low Pressure Valve Factory, etc. The product name is generally High-Performance Three-Eccentric Multi-Layer Hard-Seal Butterfly Valve SPD343H.
Simple: use a good PTFE lining, as PTFE can withstand temperatures of around 220 degrees.
It’s a very common issue; we have no choice but to switch to gate valves! Hehe