I'm on a D1.1 2010 project (mostly wide flange connections, but a few butt weld plate splices) where the manufacturer specifies UT, but the end user has requested RT as well. On the first few plate splices we are seeing some agreement with RT and UT results, and we are also seeing a couple of examples where the UT indication is classified as a "D", but because of length the same discontinuity (in one case a slag line) is rejectable with RT.
Each method stands on it's own, and the weld is to be repaired... That said, I'm curious about anyone's experience where both examination methods are utilized on the same weld joint, and any comments you may have regarding the examination results. When we move into the beam connections, the original plan is to UT first, repairing as needed... then RT second. However, if we find that certain indications are acceptable to UT, but might fail RT we may elect to perform both examinations, then proceed with repair if needed.
EDIT Added "D1.1 - 2010"
UT and RT are not going to detect the same type of discontinuities. UT will locate those discontinuities that are perpendicular to the sound beam. RT will detect discontinuities parallel to the ionizing radiation.
I would perform UT and RT in succession and repair the discontinuities detected in one cycle rather than two separate examinations and repair cycles. If not, you could case indications until the cows come home. Don't forget, after the repair is completed, the weld must be reexamined using the same NDE.
Al
Yep, you're correct that each method has advantages and disadvantages considering orientation/detection of a crack or maybe a lack of fusion along a bevel, but slag pockets, porosity and a combination of defects resulting from a poor backgouge are detectable with both RT and UT. I'm basically after information relating to the correlation of acceptance of each method to D1.1. On occasion we'll do both examinations on ASME VIII pressure vessel welds, and UT and RT generally agree.... but I can't recall using both methods on beam connections using D1.1.
On the remaining plate splices we will most likely perform both UT and RT taking advantage of the fact the two methods compliment each other, then make any repairs and re-examine. However considering material thickness on the beam connections is much thinner I just have a sneaking suspicion that the accuracy of length and spacing measurements on the radiographs will be more exact than the criteria used to rate defects using UT, making your comment about chasing defects a very good possibility.... and causing us to amend the ITP in order to perform the examinations in succession, then move to repair when needed.
Thanks for your input.
Topic Welding Industry / Inspection & Qualification / D1.1 - Correlation Between UT and RT Acceptance
