Vessel shall be required to have Dual stamping

[darrenyee88]

Hi All,

In one of the vessel datasheet, the below note was mentioned. Can anyone explain to me what does it mean?

" Vessel Shall be required to have Dual Stamping for (1) MAWP @ - 45 Deg C (2) For Future Operating Condition : Recommended MAWP (by Supplier) to operate at -70 Deg C as per clause UCS-160 (ASME Sec VIII Div 1)"

I have read in UCS-160, it was mentioning "
(a) Vessels or components may be operated at temperatures
colder than the MDMT stamped on the nameplate,
provided the provisions of UCS-66, UCS-67, and UCS-68 are met when using the reduced (colder) operating
temperature as the MDMT, but in no case shall the operating
temperature be colder than −155°F (−105°C).
(b) As an alternative to (a) above, for vessels or components
whose thicknesses are based on pressure loading
only, the coincident operating temperature may be as cold
as the MDMT stamped on the nameplate less the allowable
temperature reduction as determined from Figure
UCS-66.2. The ratio used in Step 3 of Figure UCS-66.2 shall
be the ratio of maximum pressure at the coincident operating
temperature to the MAWP of the vessel at the
stamped MDMT, but in no case shall the operating temperature
be colder than −155°F (−105°C).

Does it means that the vessel should have a MAWP base on -70 Deg C (MDMT) even though the vessel is design for a MAWP for -45 Deg C.

Please kindly guide me and advise.

 

[SnTMan]

darrenyee88, short answer, yes. Condition (1) is your base design case. Straightforward. Condition (2) would be met by lowering the MAWP sufficiently that the -70 MDMT is met thru UCS-66(b) exemptions, or perhaps, other means such as designing for -70 MDMT in the first place.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[darrenyee88]

Hi Mike,

Thanks for the response.

Regards,
Darren