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Misalignment of nozzle-to-header joint : any tolerance ?

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aburafdi

Materials
Feb 13, 2012
48
Dear all,
Refer to thread292-290132 (misalignment of tube to header weld). In this thread it was answered by Metengr that such misplace / misalignment of joint between tube and header is a non-conformance. I fully understand this. Now my question : is there any tolerance on how much the mis-alignment is still considered acceptable ?
For example : I have nozzle to header joint. The nozzle is NPS 4 Sch XXS - grade91, header NPS 8 Sch 160 - grade91. Is misalignment of 8 mm (0.31") still acceptable ?
 
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abura...

Fabrication tolerances for piping and pressure vessels are not contained within the codes. They are a commercial matter to be resolved between the purchaser and the supplier

For pressure vessel fabrication tolerances, the pressure vessel handbook contains some good information:


Engineering companies also develop thier own standards.... I have some older versions.

Also, reportedly, you can also refer the PD 5500 Annex L


Hope that this helps.....

Let us know about your final call on this matter....
 
Mr New MJCronin's statement is correct "Fabrication tolerances for piping and pressure vessels are not contained within the codes."
However there is a widely accepted "Standard"

The Pipe Fabrication Institute "PFI ES3" Covers Fabrication Tolerances.

Go here for a complete list of all PFI Standards

prognosis: Lead or Lag
 
MJcronin and pennpiper,
I appreciate your advice. I think I need to learn more about this.
As for now, we decided to cut and replace the nozzle with a new one.
 
Ive always found the PFI standards a great resource for tools, so to say.
Does anyone know of a (PFI or other) standard for tolerances on VIII-1 vessels, other than whats listed in VIII-1 w/ respect to tolerances?
 
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