Nozzle Length

[lcmechengr]

I have two vessel fabricated per ASME Sec VIII Div 1 and they will be attached by welding nozzles togther. To make up the appropriate distance, I will be placing a small piece of pipe equal in wall thicnesses between the two vessels. The work will be performed by a coded shop. Are there any code issues with this approach? Thanks.

 

[unclesyd]

I think you are OK by code but you will have some very real mechanical issues.

Can you comeback with the physical parameters of the connection and the environmental conditions?

 

[13114WANI]

Per Sec VIII-1 U-1(e)(1)(a) The code jurisdiction ends at the first circumferential welded joint. As I understand what you wrote you would be attaching the nozzles not to each other but to a length of pipe. I believe you're safe as far as VIII-1 is concerned, but check with your PE / AI / AIA to see if you need anything additional from the B31 series.

 

[MJCronin]

There are probably no code issues, but there may be structural/support issues.

Is one vessel above the other ?

How are the two vessels supported and does your small piece of pipe cause instability problems ? Does the small piece of pipe physically support one of the vessels ?

-MJC

 

[jehan17718]

lcmechengr,

MJC is correct to point out that the complexities will involve the design of suppports.

Direct nozzle to nozzle flanged connections are fairly common [as in the case of VERTICALLY stacked HORIZONTAL heat exchangers]. If your 2 (or multiple) equipments are one over the other then it is recommended to insist that the equipment supplier do a mock assembly of the stacked unit at shop. Shim plates (if required) will also have to be supplied by the equipment manufacturer.

Be advised that if you are having large nozzles directly connected to each other than you need to evaluate the nozzle loads. This could be other issue you may have to deal with.

Hope this helps.

-jehan

 

[vesselfab]

I have seen slug catchers attached like this and we had to mock them up in the shop since there were 4 interconnecting pipes between the vessels and then post weld heat treat each of the vessels seperately and then recheck after post weld heat treatment. But they were flanged instead of hard piped for ease of assembly at the user's location