PRV seat melted

[prq123]

We had a pilot PRV stick full open for about 12 hours. When the PRV was taken offline fore repairs it was noticed that the PRV soft seat had partially melted along the outside edge. The melting temperature of the soft seat is > 160 deg C, however, the measured gas temperature during the relief (and normal operating temperature) was only 100 deg C. The gas temperature has never exceed 110 deg C during the entire PRV life. The PRV discharges to a flare header and the fluid is clean natural gas. The upstream pressure when it was stuck open was around 67 bar.

Does anyone have ideas on what could have caused the PRV seat to melt? Could it have melted when the PRV was stuck open?

 

[olcrazy1]

go with a teflon seat if your pressure is high enough to make it seal.

 

[itascot]

prq123, I hope you have the time for one last question (that i am surprised hasnt been asked to date) can you supply a photograph ? I have good experiance on SRV's and the problems you describe to me are not linked to product temperature (as all data indicates this is not the root), rather localized in seat area (stuck open very slightly for the whole 12 hours I suspect, high flow through small area...again suspect, heat generated in exhaust flow vortex...again suspect). One picture is worth a thousand words.
Ciao,