Friday, February 4, 2011

RE: [MW:9712] Weld seams coinciding

Hi Eduardo,
 
I looked for answers in B-31.1 & 31.3 code , but unfortunately could not  locate anything very specific to the above problem. I know ASME Sec-VIII, DIV-1 have very clear rule on this (see below).
 
Also see below the extract from piping  fabrication standards of  an European (Anglo Dutch) Major Oil company, which provides guidelines on staggering of welds and enforcing quality of such joints.
 
In you case staggering of weld joints in not possible, the suggested things would be to:-
  • Use RT film (as wide as possible ) to cover the  circumferential welds + at least 1 inch of each intersecting seam weld (for 100% RT welds).
  • For spot welds, ensure that a spot RT must be taken at the intersection to cover welds in both the circumferential  direction + at least 1 inch of each intersecting seam weld.
I would think that would make the things easy.
 
Let me know if it helps.
 
Thanks
 
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist & Consultant
Ontario, Canada.
Email-pgoswami@sympatico.ca,
 
 
ASME Sec-VIII, DIV-1

UW-9 DESIGN OF WELDED JOINTS:(d) Except when the longitudinal joints are radiographed 4 in. each side of each circumferential welded intersection, vessels made up of two or more courses shall have the centers of the welded longitudinal joints of adjacent courses staggered or separated by a distance of at least five times the thickness of the thicker plate.

 

 

Oil Industry Specification:-

 

Assembly of piping components: For butt welding of all piping components (e.g. pipe ends, fittings and welding neck flanges) a uniform root gap shall be provided as specified in the relevant Welding Procedure Specification. Unless otherwise stated on the isometric drawings, the bolt holes of all flanges shall straddle the centre lines of the pipe ends.

 

The minimum distance between the edges of two pressure-containing welds shall be 50 mm or twice the thickness of the thicker pressure part, whichever is the greater. This is required also for the distance between non-pressure attachment welds to a pressure containing weld. Longitudinal welds in two adjacent pipes should be 180° apart, but in any case shall be separated by at least 50 mm or twice the wall thickness of the thicker pipe, whichever is the greater.

 

If the pipe contains a longitudinal weld, this weld shall not be located at the bottom of the pipe after installation; it should be located at least 45° from the bottom of the pipe.



From: Eduardo Calva [mailto:eduardocalva@hotmail.com]
Sent: Thursday, February 03, 2011 8:52 PM
To: pgoswami@quickclic.net
Subject: RE: [MW:9488] Weld seams coinciding

Dear sir, as I have seen you have a lot of expertisement.
 
Could you please help me with the below said about the elbow seams coindiding in a gitrh weld?
 
There is something in some code, or spec about it?, in order to support?, I think by radiographing and make sure that there aren´t defects in that weld crossing.
 
Thanks a lot


Eduardo Calva



 

Date: Wed, 26 Jan 2011 11:00:40 +0000
To: materials-welding@googlegroups.com
Subject: Re: [MW:9488] Weld seams coinciding
From: muthu_barathi@rediffmail.com

Hi.

no problem just take Spot RT on + joint to ensure any weld crack or any
defects at intersection and found Ok release the joint. All codes
permits.



On Wed, 26 Jan 2011 10:06:34 +0530 wrote
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Dears, we have a weld joint between elbows in which the seams coincide.
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>
How can we support this issue?, the restriction is only for pipes or
for elbows as well?
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>
Thanks for your help.
>
>
>
Eduardo Calva
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