The default type of test required for welder performance qualification is destructive testing. Many people think that “bends” can be performed instead of RT but when reading most codes in the US, the opposite is what is spelled out. As a matter of fact, there is one code of construction that refers to ASME IX that REQUIRES destructive tests be performed. I am pretty confident there are more than a few pipe welders that passed RT on a coupon in a test situation that are welding on B31.3 High Pressure Category piping…but that’s another story.
Also, for small bore <1″ OD per ASME IX, that 6″ of weld length requirement only applies to RT. You can weld less coupons if bent! But…another topic.
But in almost all codes, there is an allowance for choice of the type of bend to be performed. I’m not gonna go over what the codes say but I do want to address some differences.
Face and Root Bend Results
Below are the images of the face/root bends. During training, we cut up the entire plate and perform various bends. In this case we have 2 face bends and one root bend. I did this because short circuit GMAW is GREAT for putting in an open root. Except at tie ins, it will almost always bend. Face bends…not so much. But regardless, these would all meet the requirements of any code as far as discontinuities go.
The “SIDES” of the face root bends.
The images below are those same bends but looking at the cross section of the metal. In all three bends, you can see discontinuities in the sides…yet the bends are acceptable. Some especially “GOOD” inspectors may say they wouldn’t buy em…That’s another discussion too…but as far as what most codes say, the bends…you ONLY INSPECT THE CONVEX SURFACE. As the person who signs the bottom line, I reserve some discretionary “rights” but gotta be careful where I use em.
The Side Bends
The image below shows the remainder of the plate cut into side bends. As you can see, there are couple that just couldn’t handle the bending. Both face/root bends and side bends will elongate the outer fibers of the metal the same amount, but with side bends, the discontinuities may lie on the surface or very close to the surface and thus are subjected to all of the elongation
Is this a bad welder?
This student has shown not only skill during his training but also un unmatched perserverence. On a few occasions, he struggled with different tasks. At one point I pulled him off SMAW and put him on GMAW and he did well. When he returned to the ole 7018’s things were looking better. As welders, we are exposed to constant evaluation and “expert opinions”. We have done a 2nd attempt at this weld and I suggested he make some modifications. We will see how it goes! Image below is his next attempt. We also did a little shear wave on it to selectively pick out some side bend locations.
What bend type is “best”.
In the world of welding, “best” varies widely. For the welder performance qualifiaction and testing I perform as an AWS Accredited test Facility, I only go by the applicable code. However, each code has allowances for choice once the base metal gets to a certain thickness. Make sure you know where that is! I have also read in some code once that for GMAW, SIDE Bends were required, but my memory fails me.
If I observe a welder with an inconsistent root pass or last layer before cap, I may choose root and face bends. If I see a welder “fill up” a groove in the flat position on the low end of the parameters, I may choose side bends.
Regardless, Make sure you know “what the code says” and also maybe let the welder know.
Also, remember this, if you are bending something other than a 3/8″ thick specimen….check the radius requirements for your bender.
Peace
Gerald Austin