Help to identify nozzle to shell joint details 1

[mariolucas75]

Dear All,

Please help me to identify the nozzle penetration details:

There is a ASME VIII div 1 vessel with 24" nozzle...this nozzle as I identified penetrates through the shell...
Fillet weld between shell and nozzle started corroding... now the question is to what extent it is permisseible to corrode?
I guess the joint detail on this attached example corresponds to Figure ASME VIII div 1 UW-16.1 (e) ?
Please refer to the attachment.

Thank you very much

 

[SnTMan]

I don't find your attachement of much use. But:

External welds generally do not have corrosion allowance applied. You'd have to check the nozzle reinforcement calculations and Code required minimum weld size to know if you have any allowance.

Internal welds usually have full vessel corrosion allowance applied. Again, check the calculations and Code requiired minimums.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Snickster]

It is hard to tell what parts are the vessel and what parts are the nozzle.

The larger weld is a partial penetration groove weld that is finished over with a fillet weld.

The smaller weld is a full penetration groove weld that is finished over with a fillet weld.

The weld you show in the ASME detail is a full penetration double groove weld finished over with a fillet weld on the outside of the shell to nozzle connection.

So ASME weld detail is not same as either of the welds.

 

[mariolucas75]

The drawing attached (the link in my previous post) is from vendor that specifies the nozzle to vessel connection details...which i am trying to understand..
and one of the questions is - to which ASME weld joint example it corresponds? It should correspond right to at least some example from ASME right ....

 

[r6155]

Any photo of corroded part?
Regards

 

[jt1234]

Mariolucas, The weld overlay design and nozzle to shell junction design by vendor is very common and has been done thousands of times.
The sketch you cited from code is correct. Code specifies minimum throat depth and vendor will convert to leg size. It will be 3/8" or 10 mm leg weld size in most cases. Vendor will just show the leg size on dwg and calc. Vendor will not waste time and money for extra fillet weld size. However during actual welding, the fillet weld size or throat depth may be greater than design.
Your concern is corrosion and if what's left sufficient or not. It is very simple: clean up the weld, measure the two weld legs sizes, then hand calc the throat depth, and compare with design dwg or calc. If below design, you will need to do repair.
Corrosion on outside may be from many sources, rain, moisture, improper coating, poor insulation. In extreme hot vessel, painting will be burn off and in case shut down for some time, can cause corrosion to bare metal if moisture coming in or below due point.