ASME 16.9 End Cap Weld Detail

[oceanactive]

Hi all,

I am relatively new to pressure vessel design and am looking for help to specify the details for the circumferential welds connecting ASME B16.9 SS304 4" end caps to a 4" pipe with matching wall thickness.

The intent is to create a full pen. butt weld from on side with no backing while purging the internal volume of the vessel. The vessel is too small to weld from both sides, but the EN 13445-3 code that I am using states that the single sided weld is not good for fatigue unless full penetration can be verified - Table A2 ref C11. We can get a visual on the weld through the nozzle holes in the center of each end cap, but there certainly isn't budget to get these UT'd for such small vessels. My assumption is that a visual inspection doesn't count as verification.

This is a small vessel and low pressure (6 bar), so relatively low associated risks, but I would still like to understand how to design the vessel to meet the code.

I must be missing some obvious industry standard detail for welding small end caps of this type?

Kind regards.

 

[EdStainless]

You didn't give us a wall thickness, welding in multiple passes?
If so then visual after the root pass should be good.
You could even do fluorescent dye to verify on the ID of the root pass.


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P.E. Metallurgy, consulting work welcomed

 

[DekDee]

I do not have access to the code you are referring to but generally the applicable code (or project specifications)will tell you minimum NDT requirements.
If the code you are working to states nothing other than "full penetration has been verified" then a visual inspection of the root showing no lack of fusion or lack of penetration is sufficient.
Just FYI - normally these would be radiographed, not UT tested.