Pipe welded to Flange Hub

[TechThrm]

Hello Friends,

I have a question on a jacketed ASME VIII Div.1 vessel.
In my design the Jacket closure (0.375" thk) is welded directly to the hub of a WN flange. Is there any section in the code that prohibits such weld? The weld looks vey similar to Fig 9-5 [i-1(a)]. Attached is a drawing for reference.

Thanks & Regards,
TechThrm

 

[pennpiper]

TechThrm,
The company, Controls Southeast has a special flange just for this application,look here:

http://www.csiheat.com/products/jacketed_piping/standard_jacketed_piping.aspx

prognosis: Lead or Lag

 

[moltenmetal]

There's nothing special about that jacket attachment arrangement, and no special flange is needed. If the jacket conditions are significantly higher in pressure than the process side such that the flange rating might be affected, I'd suggest additional analysis, but it's usually the other way around- the jacket is typically a low pressure service. You can do the analysis for the low pressure jacket cases too, but the flange hub on a weld neck is thicker than the flat end plate you'd need to use if you stopped the jacket short of the flange, so it's obvious that it's OK.