Nozzle replacement for API 650 tanks 1

[mc12]

Hi all,

This is the case: Is it possible to remove a 10" nozzle and to install a new one by using the same opening and reinforcing plate (without removing the reinforcing plate)? Do I need to remove the reinforcement plate and install a new one? if it can be done, I wonder if PWHT should be done. [NOTE: The shell thickness is 7/16" (11.11mm)]

I looked for it at the API 650 and 653, and I couldn't find good answers to these question. API 653 section 9.8 "Addition or replacement of shell penetration" specifically section 9.8.6 describes a procedure for the installation of a nozzle larger than 2" NPS where the shell plate thickness is greater than 1/2".
Section 5.7.4 from API 650, doesn't describe a procedure for thermal stress relief that applies to a shell plate thickness smaller than 1/2" and an opening conextion smaller that NPS 12. Section 12 from API 653, specifies some NDE procedures.
So, I wonder if some of you guys can give a hand, or a hint!!

Thanks in advance

 

[fegenbush]

I suppose it is possible to do as you describe. I don't know how much the field personnel will like you for it, since it is likely that the cut edges will require gap-filling welds.

As for heat treatment, it would be required if the nozzle was a flush type connection, per API 650. Other reasons for heat treating are to reduce the effects of stress corrosion cracking in caustic service.

If you require additional information, I believe you would need to provide additional details of your repair.

 

[mc12]

Hi fegenbush, Thanks for you comment!

This is a NPS 10 nozzle which is located at ~460mm measured from the bottom of the tank to the center line of the nozzle.The current nozzle has an internal projection of ~1/2" or less. The new nozzle would be a double flange nozzle with an internal projection of ~ 225mm. The content is not highly corrosive, so it is not a critical service. [NOTE: The shell thickness is 7/16" (11.11mm)]. So I wonder if the current nozzle can be ground off, an a new nozzle with the characteristics mentioned above , can be installed. I also wonder if the reinforcing plate should be removed and replaced or not. Is PWHT required? According to API 653 Sec 12, some NDE are required
Thanks in advance
Cheers!

 

[IFRs]

If you follow API 650 and 653 you should be OK. Use the correct thickness and grade of material, change from a partial to a full penetration weld detail, perform the appropriate NDE and possibly some extra NDE if you are worried. Replacing the reinforcing plate is OK - you can grind off the fillet welds and UT the shell where new welds will be made. However, if the shell is a grade IV or higher material you can't do this at all per the code because PWHT is required and you can't field PWHT.

 

[JStephen]

Can you weld a short pipe and flange onto the back of the existing nozzle without removing the nozzle? That would be simpler.