Two MAWP for Div-1 Vessel
Two MAWP for Div-1 Vessel
(OP)
Dear's,
I would like to know if it is possible to mark 2 MAWP @ 2 Temp on a same ASME Nameplate. The Vessel is single chamber and not multi chamber. I want to certify the vessel as per 2013 Div-1. I am aware that a range of MAWP is not acceptable as per Interpretation.
Need your support.
Thanks in advance...
I would like to know if it is possible to mark 2 MAWP @ 2 Temp on a same ASME Nameplate. The Vessel is single chamber and not multi chamber. I want to certify the vessel as per 2013 Div-1. I am aware that a range of MAWP is not acceptable as per Interpretation.
Need your support.
Thanks in advance...





RE: Two MAWP for Div-1 Vessel
Per 2011a edition of the code, see UG-116 footnote 37.
Per 2013 edition of the code, I can't seem to find the footnotes in the digital version of the code that I have... have they reorganized the code?
RE: Two MAWP for Div-1 Vessel
They have reorganized the footnotes, they are now located just after the non-mandatory appendices. See Endnote #10:
"When a pressure vessel is expected to operate at more than one pressure and temperature condition, other values of maximum allowable working pressure with the coincident permissible temperature may be added as required. Sss UG-20(b)"
Cheers,
RE: Two MAWP for Div-1 Vessel
RE: Two MAWP for Div-1 Vessel
RE: Two MAWP for Div-1 Vessel
To be honest, I know of this rule with respect to MAWP, but have yet to actually apply it to a vessel design. A similar situation however where I have used multiple design conditions was for the MDMT of vessels containing pure fluids.
In this case, since the saturation curve is well defined, you are able to specify multiple MDMT temperatures at different pressures. When the vessel is at its coldest temperature, the pressure is also at the lowest pressure so you can take advantage of reduction curves such as UCS-66.1. As things warm up, the pressure increases, but you also don't need as much of a reduction. I think we analysed three different MDMT conditions.
Otherwise, I could imagine all sorts of crazy control systems involving three-way valves with two relief valves etc... But until I've suffered through a HAZOP looking at this issue, I don't know what would fly.
Cheers,
Marty