Research Related to minimum distance between welds.

[pipewelder1999]

The question here is related to a discussion I have had and observed many times over the years.
I'm not interested in what codes/specifications say or do not say, I'm interested in research that shows the results of the "Welds too close" topic that has been addressed here, on jobs, and other places online.
I read through one paper at https://www.researchgate.net/public...uctures_Pipelines_And_Piping_State_Of_The_Art that have me some other references but as someone who is NOT an engineer, this will take some digesting.

I am looking for something definitive that contrasts the difference in mechanical properties resulting from the welds being "too close". I am continuing to look and learn but any information is appreciated that can lead me to the "why and when" separation of welds by a specific distance should be a consideration.

As an inspector, I don't make engineering decisions but this topic has come up many times.

Thanks.

Gerald Austin
Greeneville TN

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[EdStainless]

It depends.
Regardless of what happens to the material the inspectability is the first question to address.
How are you testing and can you do it properly with very closely spaced welds?
In materials that are very forgiving of welding it has virtually no impact on the properties.
In materials with critical preheat and PWHT criteria then you can mess with things if the HAZs overlap.

 

[pipewelder1999]

It depends.
Regardless of what happens to the material the inspectability is the first question to address.
How are you testing and can you do it properly with very closely spaced welds?
In materials that are very forgiving of welding it has virtually no impact on the properties.
In materials with critical preheat and PWHT criteria then you can mess with things if the HAZs overlap.

I have seen the ability to inspect referenced in project documents before. Until the welds overlap, Visual of each joint is possible. RT and offset could definitely be an issue.

I would think that if each joint is welded individually, preheat of each joint is correct. I understand thermal gradients changing with concurrent welding but each individual weld made "properly" is what I am interested in. And you touch on the next thought, if it does "harm" the product, can it be corrected with proper PWHT.

Thanks for the thoughts.