PD5500 Vessel bottom dome to be patch repaired

[Naidooru]

Hi all,

I have a vessel that was constructed within the PD5500 criteria. It has been in service for many years and is a rubber lined vessel due to service reasons. With the rubber lining failing we have to repair the corroded area with a window patch repair. If i use NBIC & PCC-2 to do this patch repair am i doing the correct thing?
PD5500 says that it is generally used for new fabrication, and that it may be used for repair purposes but also it doesn't limit us to using PD5500.
We will be using the guidelines in terms of design thickness, materials and the welding Procedure under the BS requirements but we will be using NBIC & PCC-2 to have a criteria for inserting the patch repair as they address such repairs. Please advise me on the correct approach to do this repair or validate my current approach.

Kind regards
Senior Inspector Pressure Equipment

 

[Duwe6]

PCC-2 meets ASME and API requirements. That is all that is required. NBIC will end up telling you to "return the vessel to an As-New condition". You will probably do that anyway, using an insert 'window' patch, assuming you match the original material spec and thickness. But the whole purpose of PCC-2 is to allow a vessel to be 'Repaired' to "good enough for continued service". NBIC does not allow that; under it your repair always ends up being "Rework to As-New Condition". Some days you do not need As-New.

To me NBIC makes you buy a entire new wheel and tire, when all you had was a flat tire. PCC-2 makes sense to me.

 

[metengr]

That's the way it is because sometimes during a blow-out a wheel becomes damaged and can't provide a proper seal for a bald tire. The NBIC does not deal/concern with temporary repairs. Otherwise, try to convince the regulatory body or the insurance company for using temp repairs if the vessel is not regulated.

 

[Naidooru]

Hi All,

Thank you for the replies, great insight. I do feel that NBIC is a bit ridiculous and vague but it does refer to PCC-2 as reference for conducting patch repair thus the sequence of usage. This vessel is regulated under the South African Pressure Equipment Regulation. PD5500 does explicitly says that it is a new code of construction and it may be used for guidance of repairs and at the same time it doesn't exclude any post construction codes. Under our schedule of accreditation we mention NBIC and PCC-2 but is PCC-2 referred to as a code or specification??

 

[metengr]

ASME PCC-2 is an ASME standard.