We have a vessel that was built to ASME section viii div 1 code but it has no stamp. It doesn't have a pressure or vacuum rating. It's operating window is - 15 in WC to 20 in WC, and the worst case relief scenario would be an inflow of 23000 Scfh. Our company is requesting that we determine the MAWP of this vessel so that we may be able to ensure the relief is set correctly. Currently, there is a 2" disc set at 14 psig, which can handle the 23000 Scfh scenario.
I don't believe this is the correct path (re rating the vessel), for the process won't reach any significant buildup of pressure due to open vent lines and design flaws. I believe that setting a relief device at a much lower pressure (around 2-3 psig) would be preferable. Is there any policy/guideline regarding atmospheric rated vessels and having a relief device set above atmospheric?
Thank you in advance
Without a stamp or ASME pressure vessel certification you don't know know what you have without a full investigation of the design and actual manufactured details. There are proof-pressure test procedures that may allow you to understand and certify the vessel.
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