Is there a minimum nozzle length requirement?

[Patassa]

Hi,

We're having some issue getting the clearance we need between an instrument and a guard rail. We're cutting in two new nozzles on a furnace and the question has come up, "Can we shorten the nozzles?" to give us a few more inches. Right now we've drawn the nozzles 12" long from the wall to the flange.

I've been digging through the codes and the clients specs but can't find anything that states a minimum nozzle length.

Can someone throw me a bone?
Thanks

 

[fegenbush]

To what standard or code is the equipment in question built? Without that information, I don't think you will find much help.

 

[racookpe1978]

You HAVE to be to get adequate access to the nozzle-PV wall weld to weld all around that joint. (Assuming the PV is built or cast, then the nozzle holes drilled, then the nozzles welded on to the penetrations.)

If the nozzles are cast in pace with the PV walls, and then machined as a part of the casting, you need to address how the machining tools can get to the face of the nozzle to drill and mill accurately and square to the nozzle face.

 

[mathias28]

I did a ASME VIII div 2 vessel, 61mm wall thickness, 1200mm ID with many nozzles.
One of them was a 1" bore nozzle. What I did was machined a block about 8" OD x 1" ID x 90mm length (a bit over the wall thickness) then machined a 8" hole at the vessel wall and placed the nozzle set-in. The nozzle had to have the vessel ID profile machined on the bottom to be flush with the vessel ID.

The resul was a almost flush nozzle (10mm off the vessel wal)

ASME VIII div 1 does not have such kind of nozzle geometry pattern but by using div 2 I could approve it by FEA without problems.