Valve packing issues
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The process medium flows through pipes at 260°C and at a pressure of 6 MPa; however, PTFE was chosen as the filler for the valves. Upon verification, it was found that this filler does not meet the required temperature resistance standards. The plant has already started operating, and the valve manufacturer was contacted. The manufacturer suggested replacing the filler during the next shutdown, stating that although PTFE fillers have poor temperature resistance and may deform initially, the high temperature prevents leakage as the softened filler does not leak out. Leakage will only occur once the temperature drops and the PTFE filler cools down and settles back into its original shape, during the next startup. Is there any logic or basis to this reasoning?
If the filler is only PTFE, leakage may occur after long-term use at 260°C. The sealing structure also matters.
At a temperature of 260, PPL should be chosen, right?
This pressure is also beyond what can be tolerated; PTFE can withstand at most 1.6 MPa, while modified versions can handle up to 4 MPa. Under such pressure and temperature conditions, it’s best to use PEK