Re: Looking for a welder and his experience
Pretty shabby furnace braze job with preforms is my guess. Leak detection with leaks marked and stick and torch brazed I would guess.
The trouble with furnace brazing is that weak spots with poor penetration are not visible and it all looks rosy. The same goes for general welding or brazing but in this case with a long length of seams to be filled one weak spot leads to total failure.
The large number of touch ups here means many weak spots were not found.This part should have been scrapped just on the percentage of fixes required basis.