Nozzle bore machining

[dbday]

Hi,
I have a flanged (weld neck) 4"NB nozzle (set on) in XS pipe on the side of a small pressure vessel.

My customer wants to insert a measurement device in through the flange/nozzle into the vessel, but the outside diameter of the instrument is 100mm, which is bigger by about 3mm than the bore of the nozzle. The required thickness for the nozzle wall is 5mm, so this would not be compromised by machining.

I've told the customer that it won't fit, so now they want me to bore out the nozzle to allow the instrument to fit, so yes, they don't want me to cut off the nozzle and fit the correct size.

To me, this is mad/bad/wrong, as I would need to bore out the root of the flange/nozzle weld and the root of the weld at the nozzle/vessel junction, so somewhat more than simply dressing the weld, or removing some excess penetration !

But, is there actually anything within ASME that says "don't do this", or some paragraph/best practice elsewhere that I can quote to him, that says "don't machine away the root of a weld" because this or that happens ?

Any help with some arguments to fire back at him would be appreciated.

 

[r6155]

No problem, but first Need check the reinforcing of the nozzle.

Regards

 

[XL83NL]

Machining away the excess root penetration of a weld is never an issue, probably an improvement in most situations. Provided you don't machine away material that is required for Code calculations (ie don't end up below your tmin), I cant find a direct reason top of mind to take a millimeter or so. make sure interference of the gasket face isn't jeopardized.
PS: Codes provide minimum practices, so such guidance typically wont be found in ASME codes as they're no cook books.

 

[dbday]

No problem, but first Need check the reinforcing of the nozzle.

Regards

r6155, would you recommend redoing the radiography after doing this ?