Yes definitely - the vendors of the PSVs will calculate for you a special compensation factor that allows you to test the PSV at normal room temperature, but st

Yes definitely - the vendors of the PSVs will calculate for you a special compensation factor that allows you to test the PSV at normal room temperature, but still have it open at its set pressure when it is at a higher operating temperature. They call it the "cold differential set pressure". You can calculate your own cold differential set pressure just as a cross-check against the vendor's calculation to make sure there are no misunderstandings but ultimately you should just use the vendor's value. In the case of steam, because it is obviously non-toxic and non-flammable you can just let it go to atmosphere in an emergency, so the best thing is just to let the spring of the PSV be exposed to atmosphere rather than some variable operating temperature.