Replacement of Heat Exchanger Components - Repair/Alteration/New Equipment?

[marty007]

Hello,

When a fabricator is to supply replacement components for an existing heat exchanger, is this normally considered a repair/alteration/or new equipment?

For example:

The fabricator supplies a new shell for an existing u-tube heat exchanger. The fabricator will never see the existing tube bundle or channel as these remain at site. Can the new shell be registered as its own pressure vessel, or should the whole job be considered a repair? If we add say an extra nozzle to the shell, does this change things?

Another situation, say for the same heat exchanger described above the fabricator is only asked to supply a new bundle. They will never see the channel or shell, how should this situation be handled?

I've heard mixed responses to these questions over the years, but have never seen an official document explaining how to handle these situations. If anyone can point me in the right direction, it would be much appreciated.

Thank you,

 

[metengr]

Usually, in-kind pressure part replacements are considered repairs under the National Board Inspection Code, which is one of the few, if any, in-service codes that deal with inspection, repair and alterations of pressure retaining items. An alteration is when the pressure retaining capability of the item is changed (high pressure or operating temperature), where alteration is involved.

 

[metengr]

Correction - high pressure and temperature should really be (higher pressure and temperature above design conditions).

 

[GenB]

mechanical assembled tube bundles are sold in the open market with or w/o ASME certifications nor NB registration.
Mechanical assembled shells Shells will need to be Mfd by a proper Stamp Holder
and with proper stamp and certification. stamped as part and may be registered with the NB.
Then can be assembled in the field by a non stamp holder.The owner's obligation is to inform the jurisdiction to get the assemble inspected.

The above is what is taking place, The National Board has not ruled on these, I have red postings and Interpretations in where the NB says that will not get involved.
I would like to hear other opinions and expertise..