I often hear people saying “Metal seated valves with graphite sealing don’t need to be fire safe tested, as all the components are fire resistant”.
To be honest, starting my career as a valve engineer, I was convinced, that this common understanding is true – until I did fire safe tests on my own for our Monoflange Series, many years ago. Even after this long period of time I remember very well, when we did the pre-tests. I looked very surprised, when the valve seat was leaking during the firing of the valve.