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Re: [MW:17147] Opening on longitudinal weld of the run pipe per ASME B31.3

By Materials & Welding
That means, there is no design problem/integrity problem when we are adding a branch to a seam pipe having 100% seam radiography (Weld efficiency Ej=1). 

If it is a seam pipe with  less than 100% radiography, then there is an uncertainty factor about the integrity of the joint and to be considered.

Some engineers/clients accept the intersection of branch with the radiography of seam of run pipe to 200mm on both sides, may be this will overcome the uncertainty
[spot radiography is a method of accepting the branch intersection in unavoidable circumstances (like double seamed pipe)]

Am i right?


On Mon, Mar 18, 2013 at 3:34 PM, Raghuram Bathula <raghurambathula@gmail.com> wrote:
Interesting, i do agree we have to avoid as far as possible this intersection, however in my opinion it may not be necessary to recalculate the RF pad details, as the product of SEW is already taken care while internal pressure design calculations per 304.1.2.

any example where this will differ? i mean selection of S only

i have changed the subject line to suit this topic now.

On Monday, March 18, 2013 12:09:43 PM UTC+5:30, KVH wrote:
Please refer 304.3.3 (Reinforcement for welded branch connection) of ASME B 31.3 ( on the assumption as your construction code)

Refer the definition of t=Pressure design thk of pipe. The thickness calculation for reinforcement pad is based on whether it is intersecting a longitudinal weld or not.

So as the code has given of both options (with intersecting and without intersecting), the welding is acceptable as per my opinion.

Normally the thickness of pad and welding details which is given in project standards will be on the assumption that the branch is not intersecting a longitudinal weld, If it does then the designer has to recalculate the reinforcement pad details.

As a good engineering practice, it should be avoided and it is the prime responsibility of Fabricator and site engineer to avoid this.

Please see further opinions from experts of this group before coming to a conclusion.



On Sun, Mar 17, 2013 at 2:59 PM, Anil Hegde <nott...@gmail.com> wrote:
Dear Expert ,

We have a 36 inch pipe which is welded type ,On it We have 12 inch connection which is coming on the ( long seam ) of the pipe .

Is There any code which says we can or cannot do welding on long seam of the pipe .

Requesting you for your positive feedback .


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