Corrosion allowance for Nozzle reinforcement

[mariolucas75]

Is there a corrosion allowance for nozzle reinforcements in general?
Normally corrosion allowance is for internal metal consumption for pressure vessel...

 

[cbPVme]

If the vessel is in corrosive service, the corrosion allowance typically applies to all wetted components including the nozzles.

 

[SnTMan]

If by "reinforcements" you mean external elements like pads, normally no CA applied externally, unless otherwise specified.

Regards,

Mike

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

 

[mariolucas75]

Dear Mike (SnTMan),

Thank you very much for your advises...

This question relates to following condition - a pressure vessel (with corr allowance 3mm) with 24" manway is having a reinforcing pad which externally started corroding with some metal loss... only General Arrangement drawing is available where reference thickness of pad is 15mm.... the metal loss is 1 -2 mm on significant area of the pad.
No design calculations available for the vessel - what should my assumption be?

Is the 15mm thickness pad - a required thickness of the pad and any further metal loss might be a concern and needs assessment?
Is 15mm inclusive of corr allowance - therefore pad can corrode down to 15-3=12mm
Is 15mm the vendor provided nominal and actual required thickness of the pad is in design calculations (which not available) and therefor not know (should be some less)... consequently i should not allow the pad to corrode at all coz i dont know when the required thickness starts?

Very best Regards

 

[SnTMan]

mariolucas75, OK, I uderstand you do not have the calculations, but: The vessel GA, the vessel spec sheet, the (whichever) Code forms should state if external corrosion allowance is applied.

If it is not applied, you will have to justify the condition by performing the Code calculatipns in the fully corroded condition or some form of Fitness For Service method. As was stated in your previous threaad, thread794-522253

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

 

[r6155]

Corrosion may also occur in the space between the shell and the pad.

Regards