Min spacing between 2 welds 5

[TheReaper]

Hi everyone,

I have noticed that many clients ask for a min weld spacing of 1.5 - 2 time the thickness of the shell. Although ASME Sec VII Div.1 mentions about 1.5 time the thickness there is no hard and fast rule to maintain this.

Can anyone provide me and research papers or any article son why it is a good practise to maintain a min distance between two welds.

Thank You

 

[EngAddict]

The comments by DSB123 and rhg are basically the same as the Australian standards for pressure equipment (piping and vessels), so if your code doesn't specifically address this then it would be considered good practice to follow instead.

 

[TheReaper]

@rhg thanx mate this is gold.

This sentence "shall be avoided; if this is not possible, such welds shall cross the main weld completely rather than stop abruptly near it in order to avoid stress concentration" is very interesting. I want such details so that i can decide for myself if any distance between weld is ok, or if not what can be done to counter affect the damages.

Would appreciate if any one has literature regarding the effect of proximity of HAZ due to welding.

 

[EngAddict]

MPI or DPI of the full HAZ in this region would be sufficient.

 

[jtseng123]

per Rhg citing PD5500 "...if this is not possible, such welds shall cross the main weld completely rather than stop abruptly near it in order to avoid stress concentration. ", Does it mean it's bettter we completely weld the pipe/ladder/platform support clips over the girth seams ?
For tall towers with hundreds of suppport clips, many times clips will cross over girth seams. What we have done is to notch out a small raduis on clip to clear the girth seams. If that is not neccessary according to PD5500, that will be great news to save time and money. Your thought.

 

[TheReaper]

@rhg
see attached, most of our clients specify a similar weld arrangement for cases where pad is overlapping on the weld seam.

How Come PD5500 say that the welds crossing is better than being near, what is the basis for such a statement.
Most of the petroleum company standard specify welds to not cross each other.

 

[Karloss12]

There is no mention of distance between welds in UG-36(c)(3). The only mention is in UW-14(d), which says any small openings that haven't had a reinforcing calculation must be atleast 13mm from from Catergory A, B or C welds in a shell thickness less then 38mm. But it can be within 13mm if you carry out a UG-37 reinforcement calculation.