Procedure for de-rating ASME coded vessel

[vrkleo]

Hi,

A heat exchanger manufactured in 2006, but still not taken in to service. Code of construction is ASME Sec VIII Div 1 and the heat exchnager is code stamped.

Now the heat exchanger need to be derated (Without any physical change to the vessel) for lesser MAWP on channel side. Since NBIC doesn't cover de-rating, what should be the procedure followed? The equipment location is outside ASA/Canada.

1. Can de-rating be done by the end used and a new name plate be provided by himself?
2. Is the code stamp still valid after derating? My understanding is "NO", but looking for an option to have the code stamp and certification.
3. What options I have to do the de-rating, but still to have the vessel under code stamp?

Thanks you very much for the support.

 

[davefitz]

from NB23-3 natiaonal board part 3 ( repairs and alterations) , p 78 note 10_ this code does not include de-rating of pressure vessels, but the jurisdiction in which the vessel is to be installed shall be contacted to determine the specific procedures to be followed.

 

[vrkleo]

Hi davefitx,

Thanks for the feedback! The Vessel is placed in Kazaksthan, hence jurisdiction is not applicable.

In case vessel is derated by end user himself, what will happen to code stamping? What should be done to retain code stamping?

 

[metengr]

Code stamping does NOT change. The nameplate will be revised to reflect the altered T or MAWP. This is an adminstrative issue.

 

[vrkleo]

metengr,

Thanks for the response. The ASME name plate and certificate will have different MAWP than the derated one, is it OK?

 

[metengr]

The ASME nameplate will not be altered. Instead, a new NB nameplate reflecting the derating will be affixed to the original nameplate. The new nameplate rerating design conditions will be enforced.

 

[vrkleo]

Thanks metengr,

We are now through with the procedure to be followed.