frequency stress relive after install tower.

[MicroEng]

hi all
we have a tower that include lethal content.
it stress relive & test & install in field.
we need 2 new nozzel .can we make hole in tower & weld
nozzels & local stress relive?
the tower material is as per nace MR-0175.
is hydrotest mandatorey ?
please tell me adress of Code for it.(ASME Sec VIII Div.1)
thanx all.

 

[metengr]

Several questions;
1. Is the tower a new installation (never been used) or has it been in service, and you decided you needed two additional nozzles?

2. If this tower has been in service, are you under a Jurisdiction that requires or mandates the National Board Inspection Code (NB-23)? This is a Code that deals with inspection, repair and alteration of pressure containing objects that are in-service.

The answers to 1 and 2 will determine if you need to hydrotest the tower after installation of two new nozzles. Yes, you can weld and locally post weld heat treat two new nozzles for the tower using the guidelines in ASME Section VIII, Div 1.

 

[TGS4]

When the time comes to design the local PWHT, I would highly recommend obtaining a copy of WRC Bulletin 452 "Recommended Practice for Local Heating of Welds in Pressure Vessels". It provides some specific recommendations regarding the PWHT of your exact problem.

You can purchase WRC Bulletins online at

http://www.forengineers.org

 

[MicroEng]

hi dears
thanx 4 ur good answer.
the tower is new installed & only pacivated.
the mandatory Code is ASME.
lethal content is it`s service.
is Hydrotest mandatory after install new nozzels?
best regard.

 

[metengr]

If this vessel has not been placed into service, as you state, my guess is the vessel will probably require a hydrotest because of the addition of two new nozzles. Check with your AI or Jurisdiction on this matter!