Rehydro test due to clip welding after PWHT

[leedrong]

A Pressure Vessel ( Mat'l : A516-70 * 26 t )was Hydrostatic pressure tested after PWHT and Ship out to site. .
But Internal clip (8 t * 200 W ) is requested additionaly to attach insid of Vessel with 6mm fillet weld .

Welding will be done after preheating and after heating with 212 F .

I Think Local PWHT could be get exception by Code and Client , But How about Re Hydro Test.
Should it be done or any exception approved by Code and
any other Practice in lieu of retest.

Thanks in advance

 

[metengr]

My interpretation of ASME Section VIII, Div 1 is as follows for a new vessel NOT placed into service, and based on your information - if the clip is welded directly to the carbon steel vessel wall, you will need to perform a hydrotest to satisfy UG-99 subparagraph (a)(1). You are right that for the 1/4" (6mm) fillet weld a local preheat is all that is needed - No PWHT - based on Note 2 (c) 3 of Table UCS-56.

 

[weldtek]

Correct me if I'm wrong Metengr, but I think in some instances, there may be a way to make a minor modification such as described above, as a repair, under NBIC rules, with the AI's concurrence.

 

[metengr]

The scope of weld repairs and alterations in the NBIC does not apply to new construction. From the original post, it appears that the vessel fabrication was completed and hydrotested in the shop, prior to shipment for field installation. If the paperwork has not been closed out, a re-hydrotest is required to satisfy ASME B&PV code, Section VIII Div 1 requirements for installation.

 

[weldtek]

metengr,
I was referring to a vessel that has been completed, and for which the applicable Code form ( U1/A) has been signed off by both the AI and the manufacturer. Is that what you mean by completion of the paperwork or do have something else in mind?
I'm just trying to get a better understanding of the rules.

thanks,

 

[metengr]

Weldtek;
Yes.

 

[deanc]

This also depends how the QC Manual is written and any procedures.

Is the U-1 signed/registered yet?

If the vessel is in the field,that is complete per the paperwork/QC System of the orginal manufactuer and if a "R" firm did this work,a NBIC action should be OK.

You could always ask the Local Jurisdicton. They are ones who need to be happy.

 

[solinar]

A hydrotest is a leak test primarily for welds. As long as your clip is not being installed over an existing through wall weld (such as a circ or long seam) then a hydrotest would not really do anything for you. I would guess you could probably get the AI to buy off on not rehydrotesting.