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Abusaleem
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Join Date: Feb 2009
Posts: 31

Minimum Pipe Piece for Welding

01/18/2010 7:36 AM

I have flange WNRF 1'' , shall be welded with fittings (elbow & equal tee), practically you cannot weld the flange directly to the fitting, so what is the minium pipe piece to be welded between the flange & the fitting?
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Anonymous Poster
#1

Re: Minimum Pipe Piece for Welding

01/18/2010 10:27 PM

If you can guarantee a full pen weld there is no reason you cannot weld fitting to fitting.

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qaqcpipeman
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Join Date: Sep 2006
Location: Western Pennsylvania, USA
Posts: 761
Good Answers: 9
#2

Re: Minimum Pipe Piece for Welding

01/18/2010 10:35 PM

A group of peers and myself had this same discussion today, as the previous answer tells you, it is at your discretion as long as you can make the weld and prove it through NDT.

No particular code we found addresses it, except API 1104 and that is very vague.
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SloopJohnB
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Join Date: Sep 2007
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#3

Re: Minimum Pipe Piece for Welding

01/18/2010 10:38 PM

If it was a SO flange you would need to add a short piece of pipe so there is a minimum of 3t (pipe wall thickness) between the welds. As it is a WN it can be welded fitting to fitting allowing for the root gap.
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Abusaleem
Associate

Join Date: Feb 2009
Posts: 31
#4

Re: Minimum Pipe Piece for Welding

01/18/2010 11:51 PM

Fisrt Thanks for all

Actually we make piece of pipe 10 mm just to connect the flange with the fittings.
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Abdel Halim Galala
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Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

Join Date: Feb 2007
Location: Cairo, Egypt
Posts: 1733
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#5

Re: Minimum Pipe Piece for Welding

01/19/2010 1:05 AM

"practically you cannot weld the flange directly to the fitting"

Who said that?

Practically you can weld the WNRF flange directly to any pipe or fitting. The abbreviation WN mean that the flange furnished with Welded Neck, specially designed to be welded into any (any) piping component.

But, for Slip On (SO) or Socket Weld (SW) flanges, we used to weld it to a piece of pipe with a min. distance between the two adjacent welds not less than the larger of 2-3 inches or 3 times the thickness of pipe, and that is only to minimize the heat input localization and overheating of welding portions during welding process which have a bad effect on its characteristics.

Note. In larger pipe sizes and thicknesses, you can increase the min. distance between the adjacent welds by more than the prescribed figures.

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Mechanicalmark
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Join Date: Jul 2008
Posts: 97
Good Answers: 2
#6

Re: Minimum Pipe Piece for Welding

01/19/2010 8:35 AM

I have seen specifications that require a minimum of 0.75" from toe of weld to toe of weld (unwelded pipe length).
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Anonymous Poster
#7
In reply to #6

Re: Minimum Pipe Piece for Welding

03/02/2011 2:46 AM

can you tell me what spec?
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Users who posted comments:

Abdel Halim Galala (1); Abusaleem (1); Anonymous Poster (2); Mechanicalmark (1); qaqcpipeman (1); SloopJohnB (1)

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