Re-rating vessels 1

I have a double-pipe reactor (20" ID) that I would like to re-rate for a different temperature and pressure (probably to 75 psi and 482 deg F, currently it is 145 psi and 392 deg F). Is this considered a pressure vessel or can I classify it as a speciality item? If it's a pressure vessel then it i smy understanding that I have to take a bunch of UT measurements and then pay a shop to do the calculations and give me a stamp. But if I classify this as a specialty item, then is this still the case?

thanks,
chris

 

[izamil]

Is your double pipe reactor code stamped? If yes, advise the current design parameters to which it is operating at to enable me analyze this further.
Anything at or above 15 psi is considered a pressure vessel.
Specify what you mean with the term specialty item.

Regards,

 

The vessel is not stamped, but it does have a nameplate. This is a case where a relief valve has to be put on to the reactor, and the discharge conditions are much different than the nameplate MAWP and temp.

 

[izamil]

Rating
The only people with the remote possibility of certifying the reactor is the original manufacturer as he is the only one who can stand by his previous quality and workmanship. It is impossible for anyone to certify an existing reactor built by others due to obvious reasons, and the lack of detailed information such as but not limited to i.e. welding parameters, material specifications, and extent of the Authorized inspector involvement or lack thereof.

My best suggestion for you is to approach an ASME certified shop that is a holder of the R Code stamp, and ask for his input. Tell him also about the relief valve parameters.

I am sorry I couldn’t be of much help.

Regards,

 

[twjag]

cdgilbert does not indicate vessel location & the Code required for that jurisdiction.

Re izamil's post, existing vessels can not be certified & stamped as ASME. ASME is an in process Code, & does not allow for post construction certification. cdgilbert would need to contact the Jurisdiction to determine the conditions under which the vessel may be used.

 

[JamesBarlow]

An existing vessel can be certified. We have done this on two occasions. This was a different situation for us, however, since we were the original manufacturer for the vessel so we had all the required construction, material, and engineering work for the vessel. We were required to test the vessel as we always do before code certification, but there was nothing additional required.

I don't really know about the R stamp but from what I have heard this is your best bet. Without the original construction records, and all associated documents, there is no way you can get a new code stamp for the vessel.

 

[moseley]

cdgilbert,
I suggest you check out RC-3022 in the NBIC book. It doesn't say that you can't perform the re rating but it does require sufficient tests to prove its ability to perform at this new rating. Hope this helps