Dye penetrant is another NDT that highlights cracks for visual inspection too, but it's proven to be less effective than ultrasonic and x-ray (hence the changes

Dye penetrant is another NDT that highlights cracks for visual inspection too, but it's proven to be less effective than ultrasonic and x-ray (hence the changes some years ago in the inspection and rebuild manuals by AD's for many (it should be all) turbofan engines). I knew a German engineer consultant who did this on piping, welds and pressure vessels in the field for nuclear plants. You can use all three of these NDT techniques, where are used in nuclear energy and turbofan engine applications, but still fail to detect weak welds or metal fatigue because of improper calculations or conditions in the real world. There's no substitute for DT to validate the engineering and manufacturing, such as by overpressing a pressure vessel (which are also covered by ASME BPVC). Oddly enough, I knew a civil engineer (PE) who was an expert witness and wrote code interpretations for BPVC to the tune of $40-60k per for a few hours of work (but having his experience on large industrial projects is an important prerequisite). IIRC, he had a massive house in Saratoga.