Maximum Allowable Corrosion Allowance (MACA)

[mechengineer]

Hello, everyone,
Anyone has the experience with practicing the Maximum Allowable Corrosion Allowance (MACA) for pressure vessel in your project? Appreciate if you can share your experience.

 

[SnTMan]

mechengineer, yeah I have done a few times as per client request. Total PITA as the programs typically are not set up to calculate it as they are MAWP. Each component must be examined to determine its' max CA, the least of which then becomes the vessel MACA. Then what do you do about B16.5 flanges or other standard parts?

Quote the client a healthy adder for this if you can....

Regards,

Mike

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

 

[mechengineer]

Hi Mike,
The question is same as the MAWP I raised a few days ago. The MACA shall be checked by the loadings combined (internal pressure & external loads) at the critical points, like the nozzle to shell joint and the vessel support rather than based on the internal pressue only to determine the MACA. The better way may assign the design CA as the MACA if the MACA can't be checked or calculated by the actual combined loadings. Any differnet opinions?
Thanks,
Yanhua.

 

[SnTMan]

mechengineer, sure, MACA can be determined considering external loadings as well, still, a laborious process to find MACA for the vessel. Again, one would need to lock down the existing design if the software is capable of changing it at the new CA. If you can take the design CA as the MACA that would avoid the difficulties.

Regards,

Mike



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