Nozzle welds

[Corgas]

Vessel is being built according to ASME Section VIII Div 1.

Contractor came back saying that above mentioned code does not specify UT for nozzles.

I've alwyays thought that Nozzle-to-shell penetration welds shall be 100% UT examined.

Contractor is proposing use of MT and PT in lieu of UT.

By the way, our spec calls for 100%UT but this in not my area of expertise.

Thanks

 

[Duwe6]

Per Sect. VIII, even 'Full RT' vessels do not require nozzles to be radiographed [RT] or UT'd. That requirement is solely driven by the Customer. Having said that, I would spec. nozz UT on any of my big-bore nozz's on any 100% RT vessel. It finds side-wall Lack-of-Fusion exceptionally well, which is the predominate defect, in my experience.

MT/PT of root and cap is a very poor substitute for UT of the full thickness of the weld. In reality, you are better off with an attentive welding inspector, 3rd-Party CWI prefferably, signing off on the fit-up and root of each nozz, and performing frequent [several times an hour] in-process welding inspections. 100% visual inspection 'VT' is MUCH better than MT/PT of the root [w/o seeing the fit-up], and MT/PT of the cap. Additionally, MT/PT is typically done by an NDT tech, who may not have any training in visual inspection of welds. You need a CWI.

 

[stanweld]

Nozzle to shell welds under ASME VIII, Div. 1 do not require RT or UT examination - only visual. If you wish them to be examined by other methods, they must be specified in your Purchase Documents.