Pressure vessel connection 1

[Adeeba]

Hi everyone
I have a question that
design code: ASME sec VIII-1
In body of pressure vessel, we have made connection of NPS3, later off it was decided to change the connection to NPS2.
there is an option to use reducer of 3" x 2".

Question:
is it possible to blind the connection, and drill for NPS 2 again at same place.
if yes, any reference in code

 

[chevproe]

You can install a blind on the existing 3" nozzle and make a 2" opening on the blind flange and then weld the 2" nozzle neck and flange onto the blind.
You can check the nozzle reinforcement calculation for blind flange as per UG-39 of Code.

 

[Adeeba]

Hi chevproe
Thanks for complete answer. Going in further detail,
will there be nay limit for minimum distance for welds?

 

[Adeeba]

UG-39 is about reinforcement requirements of openings in flat heads.
I am unable to see for blind flange.
Please specify.

 

[racookpe1978]

If the PV nozzle already exists, it seems much, much less expensive and wiser to use a 3x2 reducer as simple pipe fittings outside the PV. Either welded or bolted pipe fittings will be better then ANY flat plates drilled or welded across a PV nozzle!