Governing thickness for local weld repair 1

[kclim]

All,

Have a vessel with a set in protrusion - the protrusion is welded to the shell using a double J-prep, full pen.

The vessel wall is approximately 100 mm thick, the nozzle and shell both carbon steel material (low C, < 0.2%).

Have recently encountered cracking on the weld toe, shell side of the weld from the internal of the vessel. Crack depths are approaching critical size, and we would like to perform a repair.

However, we believe we should be able to perform a localised repair - i.e. excavated until crack disappears and blend. From preliminary studies, the crack is approximately 27 mm deep.

If the vessel is constructed to ASME BPV Section 8, what thickness governs the PWHT? My initial feel is that the vessel wall thickness (100 mm) will determine this, although perhaps there is some dispensation as we are not building up to full thickness?

Would appreciate any comments. Thanks.

PS - we aren't in a position to consider a temper bead repair.

 

[fegenbush]

For your repair, the weld metal deposited thickness (~1", per your post) will govern. This should be confirmed with your AI, but weld repairs on PWHT vessels are permitted per UCS-56(f)(1-6) up to 1 1/2" in depth. You must inspect to ensure you are at the bottom of the crack with MT or PT.