Minimum Weld Edge to Weld Edge Distance for Div 2 Cate D Joint

[mechmania]

I am looking for some clarity regarding what is the Minimum weld edge to weld edge distace considered.

I have Nozzle welded to Shell and Weld edge to weld edge distance for Nozzle from Head to shell seam is 20 mm.

This is Divison 2 vessel and Nozzle is Self-reinforced.

It is welded as per detail 8 of Table 4.2.10 of Div 2.

My concern is that this WE to WE distace of 20 is okay or should I consider to move nozzle and provide WE to WE distace of 50 mm Minimum? Is there a code minimum requirement?

Please provide your thoughts.

Best regards,

Mechmania

 

[racookpe1978]

Please draw your problem: It is not clear from your description.

 

[mechmania]

Please see attached Sketch along with above written description.

Hope i am clear now in what i am asking!

regards,

Mechmania

 

[racookpe1978]

Well, you have 20 mm from the bottom of the fillet to the "middle" of the end dome weld.

Which leaves open:
How thick is the material of the end dome and the tank wall?
What kind of weld and weld prep do you intend to use to attach that lower end dome to the tank wall?

In an ideal world you do not want to overlap the two welds at all, and you want to be able to keep their two heat affected zones as far apart as possible.

 

[gr2vessels]

The pressure vessel code does not specify any minimum distance between weld, simply because the welds do cross each other and they are rather subject to fabrication requirements/regulations then code requirements. It is however accepted in the industry some minimum 3 x wall thickness distance, in order to prevent overlaping the HAZ. Also, the piping code has some guidelines for welds proximity, due to the same reasons. So, if your 20 mm between weld toes is less than 3 x shell wall thickness, you might need to check the size of HAZ...As above said, ideally you'd keep the two welds apart, but if they have cross each other, is not cause for failure, but further investigation of material strength and possibly property change due to welding.
Cheers,
gr2vessels

 

[mechmania]

Thanks racookpe1978 and gr2vessels for your feed back.

In my case the Head thickness is 67 mm (MOC:CS) and Nozzle size is 2 inch Self reinforced.

What if I may not be able to move the Nozzle up at this point of time, is there additional NDE i may need to consider?

Or i should not worry about it.

F.Y.I: As i mentioned above this is Div 2 Vessels and nozzle is welded per detail 8 of Table 4.2.10 of Div 2.

regards,
Mechmania