MAWP (LImited By) 1

[darrenyee88]

I have come across a GA drawing specifying MAWP limited by shell flange , Can i know what is the reason behind it?

Also, when ask supplier to provide calculation for MAWP, the y are not willing to provide and only provide MAWP= Design pressure. Can I know the reason behind it?

Regards,
Darren

 

[fonti1977]

This means the shell flange will be the first to fail should the max allowable is exceeded.
MAWP = D.P. is ok if there are no calculations available.

 

[marty007]

Many customers will require the fabricator to show which component in the pressure vessel limits the MAWP. The shell may allow 100psi, the flange may allow 75psi, so the overall vessel would allow 75psi with the flange being the limiting part. Every component in the vessel must be checked to confirm which is the weakest part.

It is up to the customer to require the fabrication shop to provide MAWP calculations. It is often easier and provides an additional margin of safety to set the MAWP equal to the design pressure. If it's not in the purchasers specs, the shop doesn't have to provide a calculated MAWP. That said, they might be more than happy to if you pay them extra...

 

[pksingla11]

MAWP should always be equal to or greater than design pressure.

When you asked to provide MAWP calculation, vendor mentioned that MAWP = Design Pressure, which is fine. As long as vendor mentions which component restricts MAWP, I don't find any reason for insisting on its calculation.

 

[sanshu1111]

As per ASME Sec VIII (assume that this is the design code), calculation for MAWP is not mandatory and manufacturer can consider MAWP = design pressure unless calculation for MAWP is required as per the user specification/ contract.

In case manufacturer has already indicated on GA that MAWP is limited by flange, calculation for the same is to be provided.