Overlapping butt weld and fillet weld

[iceland1]

Hi,

I have a carbon steel pipe spool with a circumfrential butt weld. Very close to the butt weld there is another circular double pad welded to the pipe using a fillet weld. The butt weld and fillet weld overlap around the circumfrence of the pipe, the Butt weld was competed probably a few weeks before the fillet was added.

I know this not good and normal practice, for me at least, is to have 4 x Wall thickness or 50mm separation between these welds.

Can anyone explain why it is a problem to weld one weld on top of another like this? Can this be accepted it we do 100% radiography and confirm there are no unacceptable includions in the joint?

Any help is appreciated, cheers.

 

[ijzer]

You want to avoid stress raisers on a weld , that's why.
Grinding the butt weld flush and do 100 %RT is a common method before welding the fillet.

 

[metengr]

I really don't see this as a problem provided you blend grind the butt weld before depositing the fillet weld as mentioned above to reduce stress risers. Many nozzles and are full penetration welded and have an external fillet applied as well as repads that are fillet welded over adjacent girth and seam welds in components.

 

[HgTX]

Another example: most built-up plate girders will have butt splices in the webs and flanges, and then the web-to-flange fillet welds must pass over those splices.

Hg

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