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Weld spacing- Nozzle to circ. seam

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TJW

Structural
Jul 10, 1999
33
I'm looking for the minimum distance required between the edges of a vessel circumferential weld and a nozzle attachment weld per ASME VIII, Div.1
From UW-14, it would seem that there is no requirement for a nozzle of a size that is out of the scope of UG-36(c)(3). Per UW-14(a), any type of opening that meets the reinforcement requirements of UG-37 can be located "in" a welded joint, so does that mean also that adjacent welds could be as close together as desired (even if they do not overlap)? The only place that I could see a minimum spacing requirement was UW-14(d) which requires welds to be spaced 1/2" apart. But again, that refers only to openings meeting UG-36(c)(3), and it is for thicknesses up to 1.5" ... what if it is thicker?
The particular case I am dealing with is a 4" vessel wall thickness and a 24" diameter manway neck.
Any thoughts would be appreciated.
Thanks in advance,
Tom W
 
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There's no Code restriction to putting a nozzle through a weld seam except that you'll need to radiograph the seam on each side. There are however many client specs that will not allow this and generally should be avoided in any case. Twice the shell thickness is a rule of thumb.
 
While there are no specific rules for this, but "twice the shell thickness" rule (of thumb) seems too much for your case (Shell thickness 4-inch).

I remember a client's specification which demanded a distance of 50 mm between toes of adjscent welds. Sounds reasonable for your case.
 
Thanks for the input, I appreciate you taking the time. This confirms what I was thinking. I just wanted to make sure I wasn't missing something.
Thanks again,
Tom W
 
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