ASME Section VIII Div. 1 Vessel Stamp
ASME Section VIII Div. 1 Vessel Stamp
(OP)
This is a question regarding the specified MAEWP on the vessel's stamp. We would prefer that our vessel's MAEWP says "FV" but the tank vendor refuses, saying code requires them to put an actual number.
Currently, they are showing "15 psi". First, I find "psi" as a very gray area, especially on a vessel stamp. This "psi" indicates a differential pressure to me, which negates a reference point. I would prefer this to show "15 psig" or "0 psia". Unfortunately, their stamps are fabricated already with "psi" so a change can't be shown there. Is this common on most vessel stamps?
What is the best, and most typical way to specify full vacuum on a tank stamp?
Currently, they are showing "15 psi". First, I find "psi" as a very gray area, especially on a vessel stamp. This "psi" indicates a differential pressure to me, which negates a reference point. I would prefer this to show "15 psig" or "0 psia". Unfortunately, their stamps are fabricated already with "psi" so a change can't be shown there. Is this common on most vessel stamps?
What is the best, and most typical way to specify full vacuum on a tank stamp?





RE: ASME Section VIII Div. 1 Vessel Stamp
I'd suggest that you have your supplier read VIII Div. 1 Appendix 3-2 full vacuum (FV) and UHX-19.1. They can then perhaps explain why they still think "FV" is not code legal.
jt
RE: ASME Section VIII Div. 1 Vessel Stamp
As for UHX-19.1, unfortunately thats for heat exchangers and they could deem that not applicable since this is a 50 L vessel. All the same though - governed by ASME Sec. VIII.
But have you heard of NOT being able to use FV on a vessel stamp? I've scanned over Sec. VIII for about an hour now and see no limitations on it. Nor do I see guidance on exactly how a vessel should be stamped (numbers, decimals, etc.).
RE: ASME Section VIII Div. 1 Vessel Stamp
The point of the UHX reference is that it provides an example on how to comply with the UG-116 stamping requirements. The beauty is, one of the examples uses "FV" as the external pressure.
jt
RE: ASME Section VIII Div. 1 Vessel Stamp
Enjoy!
jt
RE: ASME Section VIII Div. 1 Vessel Stamp
RE: ASME Section VIII Div. 1 Vessel Stamp
I forgot to mention the Subject of the Interpretation: UG-116, Required Marking for External Pressure
jt
RE: ASME Section VIII Div. 1 Vessel Stamp
RE: ASME Section VIII Div. 1 Vessel Stamp
RE: ASME Section VIII Div. 1 Vessel Stamp
jt
RE: ASME Section VIII Div. 1 Vessel Stamp
Yes, they are common and acceptable. In the ASME vessel world, the unit "psi" indicated on design pressure, MAWP or MAEWP always meant gage pressure. If your preference is "psig" or "FV" (in the case of external pressure), it needs to be stipulated on the purchase order or marked up on the vendor's drawing submittals. Most vendors don't usually proceed with fabrication without drawing approvals from the client.
If the vessel is still in the vendor's shop and you still prefer to change the MAEWP from "15 psi" to "FV", they can still change it, but don't be surprised if there is a cost or schedule impact. If the vessel is already shipped, forget about it because the vessel will require a stamp "R" for the nameplate replacement.
RE: ASME Section VIII Div. 1 Vessel Stamp
Full Vacuum is defined as 15 psi external pressure in Appendix 3. Fabricators use 15 psi as MAEWP on nameplates all the time. 15 psi or FV are both acceptable.
RE: ASME Section VIII Div. 1 Vessel Stamp
The below interpretation is an example of the various interpretations in the ASME Codes. This one is specific to ASME Section I
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