Operation Outside Nameplate Values?
Operation Outside Nameplate Values?
(OP)
Hi guys. Dumb question from a Code neophyte. I am involved with a Section VIII Div. 1 vessel with nameplate stamped at MAWP of 250 psig at 100° F. The Owner wants to operate this vessel at 0.5 psig and 250° F. This of course is outside of the temperature stamped nameplate value. I believe he needs to get a recertification to operate at this temperature because it is outside the stamped nameplate. What say ye?
Thanks! Pete
Thanks! Pete





RE: Operation Outside Nameplate Values?
Cheers,
gr2vessels
RE: Operation Outside Nameplate Values?
RE: Operation Outside Nameplate Values?
If the existing MAWP can not be reused due to new higher design temp that lowers down the allowable stress, take a look on the pressure relief valve, which most likely shall be replaced for the new pressure, And also check all connecting piping. They may also have relief valve in them. Re-rating needs a system or process engineer to look at the overall picture (P&ID) and impact before it can be initiated. New design conditions shall be set by them.
RE: Operation Outside Nameplate Values?
RE: Operation Outside Nameplate Values?
RE: Operation Outside Nameplate Values?
RE: Operation Outside Nameplate Values?
You're wanting to go outside the stamp (the nameplate) but you're lowering pressure from 250 psig to near-zero. Temperature of the vessel is going up (above boiling point of water) but well below the significant loss of metal strength you get from heat. (Compare a process at 250 Deg F at near-zero pressure with one at say 800 or 900 degrees at 400 or 500 psig.)
Thus, you're going in a safe direction with the change, but still need to satisfy the legal/insurance requirements.
Tests? How are you going to verify no leaks if you don't pressurize the system? Are you sure you want to write the new label for "only" that 1/2 psig and not something higher, like 10 or 20?
RE: Operation Outside Nameplate Values?
RE: Operation Outside Nameplate Values?
RE: Operation Outside Nameplate Values?
Regards,
Mike