Recommended temperature rate during startup or shutdown
Recommended temperature rate during startup or shutdown
(OP)
I am in search of some reference document or method to evaluate the recommended temperature rate during startup or shutdown, for a carbon steel or low-alloy pressure vessel.
Thanks in advance,
Yann
Thanks in advance,
Yann





RE: Recommended temperature rate during startup or shutdown
The best example is coke drums - they are susceptible to very low cycle fatigue because the heat-up and cool-down are severe. That's not to say that this is bad - just that you need to understand it and incorporate it into your vessel integrity management plan.
RE: Recommended temperature rate during startup or shutdown
Maybe the term "rate" was not the accurate one in my question.
I will take an example : For a reactor in start-up the recommendations are: raise the temperature to 300°C at a rate of 55°C per hour. How to determine the value of 55°C without performing a fatigue analysis ? My purpose is to understand how the general recommendations for start-up are made.
RE: Recommended temperature rate during startup or shutdown
"Nobody expects the Spanish Inquisition! "
RE: Recommended temperature rate during startup or shutdown
Thank you very much davefitz for the valuable tip !
RE: Recommended temperature rate during startup or shutdown
Without performing some sort of calculation, it is impossible to know the magnitude of the stresses involved with a slow vs fast thermal and pressure transient. I've done the evaluation in some - and they've been very conservative. Others have been way off and lead to premature failure...