Use of valve packing
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The device has a leakage at the valve packing of DN40; I plan to replace it. There are two types of packing available: one in circular form and the other in rope-like form. Please advise me on which one to use
First, you need to check what the shape of your valve packing is; as long as it’s suitable for use, any shape will do. But it only applies to ordinary valve packings; one just needs to fill these materials evenly inside. However, for those set-shaped packing materials, set-shaped packing materials must be replaced, especially this is the case for packing materials in medium and high-pressure valves. Common filling materials can all be used; one just needs to disassemble them and use them. Fill it evenly roughly, then use bolts to press it tightly to ensure a uniform seal; for reference only. It would be best to take a photo of your valve and send it.
For high-temperature valves, the former (molded graphite packing) must be used. Maximum operating temperature for PTFE asbestos packing: 260°C. Operating pressure: 10.0 MPa. pH value: 2–12
Metal-graphite wound gaskets used for valve sealing
Based on the operating conditions: graphite is primarily resistant to high temperatures and has good self-lubricating properties. Of course, during the installation process it is necessary to check whether this ring-shaped packing will suffice; for high-temperature conditions, graphite is definitely the suitable choice
Both should work; the former has better performance than the latter
Is it still allowed to use asbestos-based packing? Weren’t asbestos products already banned from use? For media with operating temperatures between 200°C and 425°C, graphite-woven packing can be considered; for temperatures below 200°C, PTFE-filled packing that has been molded into a specific shape may be suitable. However, if the medium contains substances such as butadiene that can dissolve PTFE, then molded flexible graphite packing should be used. Personally, I think using molded packing is more reliable if the dimensions match
It depends on the gasket material used for the valve
Everyone is right; opening the original valve and using what’s available is simpler
Specify clearly the valve pressure, medium used, operating temperature, etc