Skirt to Base Ring Weld

[waskillywabbit]

Good morning.

Typically, we use a standardized detail that makes the fillet welds (inside and out) the same thickness as the skirt, on the skirt to base ring connection. However, due to bolt circle limitations (just not enough room for such a huge fillet weld and get the nuts on there) and a skirt thickness of 1" (not necessary to meet calculations but customer specified) a 1" fillet weld inside and out is a bit absurd/overkill. I consulted the ASME code books, the pressure vessel handbooks I have in my library, looked at my COMPRESS calculations and could not find anything specifically addressing these welds and their necessary size. They all show "pictures" of them, but nothing else. Tower is 50' O.A.H. and 150" OD.

I searched the forum and found nothing.

A link and/or input would be appreciated.

Many thanks.

Brian

 

[metengr]

Go back and discuss this with your customer. If they are specifying this weld detail, you need to resolve this engineering detail with them directly.

 

[waskillywabbit]

Sorry for the confusion...they haven't specified any weld detail. I'm just looking for some material that addresses this connection and looks at the welds...rather than just relying on standard details. The above situation just brought it to my attention and it is a good example for examination purposes.

Thanks.

Brian

 

[metengr]

waskillywabbit;
Ok. I know that AWS has a reference book on proper sizing of fillet welds. Most likely, you will not find specific information in the ASME B&PV Code. Can you go back and knowing the design loads on the vessel size the welds using an appropriate safety factor?

 

[waskillywabbit]

metengr,

I've already done so using the actual loads w/ appropriate safety factors. It will be more than adequate. I guess I was just looking for some code guidance or procedure other than just "good engineering design" or standard details. I'll go find the AWS reference book and give it a glance.

Many thanks.

Brian

 

[codeeng]

Go back and look at the calculated skirt thickness and use this as a basis for the amount of weld metal for the 2 fillet welds using the throat thickness. If the skirt thickness includes a joint efficiency of 0.55 or less then you don't need to apply any additional joint eff. to the welds.

 

[JStephen]

Just size the welds for calculated uplift, perhaps for bearing downward, + CA.

 

[waskillywabbit]

codeeng
Go back and look at the calculated skirt thickness and use this as a basis for the amount of weld metal for the 2 fillet welds using the throat thickness. If the skirt thickness includes a joint efficiency of 0.55 or less then you don't need to apply any additional joint eff. to the welds.

This is actually what I did.

Brian

 

[codeeng]

So then you come up with a weld size of X" and everyone is happy.

 

[carthago]

If you know the weight and moments acting on the skirt (Empty weight, full weight, hydrotest, overturning moments due to wind and earthquake if any) then you can check the required fillet weld size by using the basic formulas given in Blodgett or Bednar.
You can and a few mm ( 2 mm for instance for corrosion).

 

[waskillywabbit]

As usual, thanks everyone for their helpful comments!



Brian