X Ray vs UT

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Ok guys so which do you find picks up on more issues X ray or UT ?Im working on a big manifold system for the offshore, all Duplex pipe 6", 8",10" sch 160 pipe.   The joints are passing X ray but failing UT.  Not all 6 joints out of 300 have failed.   The ones that failed I didn't weld on..   Is it normal for UT to pick up on stuff and X ray miss it ?One joint in particular showed a 20 mm lack of fusion on X ray,  but UT showed lack of fusion at all layers of the weld.I always figured one was as good as another.  But its looking like UT out does X ray.Journeyman / Red Seal Welder (What a useless test)Miller CST 280Miller XMT 350Miller 12vs XtremeEvolution Evo 28 mag drillEvolution 380 Dry Cut saw
Reply:UT is only as good as the person running it. If their trigonometry is off you can be looking in the wrong place. But you need UT to tell the depth on an X-ray. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:X-ray shoots through both sides of the pipe so you could potentially have more density in a weld because of where the source sits across the pipe letting the X-ray pass the ut will not give you that benefit
Reply:What are they using for couplant in regards to UT.  I've heard of instances where couplant will cause rusting on stainless and duplex.  I favor X-ray.  I'm certified in UT and will agree with what CEP said.  It's only as good as the person using it.  It depends on the joint as well.  Anything with a backing bar would be better with RT.  UT and RT both have their place.  In my opinion it depends on the joint.  UT doesn't pick up porosity very well at all.  I'd rather have x-ray.  At least it's there instead of possible false indications causing cut outs.  Just my opinion.
Reply:Each has its applications.  With X-ray I have found that the defect shows but you are never really sure about depth.  A following UT is helpful to find out from which side you gouge.  I have been asked to do a repair on the flange material for a welded beam.  The tech marked where the flaw was and approximate size.  I gouged as carefully as I could until I was half an inch from the other side.  I decided to weld it up assuming that I missed the flaw.  The joint was X-rayed after we went home at midnight.  The negative passed but when the white hat asked how deep it was I had to admit to him I never found it.  UT can be done with everyone working around the item.  X-ray requires everyone to clear from the shop for a few minutes while the tech does the exposure.  I notice that pipelines are using a UT scan that is much like bably pictures giving a full picture that can be downloaded to become a permanent record much like an X-ray negative.  A Newfie mentioned cold shuts or tight laps with no fusion will not necessarily show on X-ray.  If the cold shut is tight then the X-rays pass through without being blocked so the fault does not show up on the negative.  The sound waves however reflect off the cold shut.  I always remember walking by the open door of the foreman's office.  To this day I remember him screaming at the welder standing there looking at the negative.  " You saw it! You saw it! And you welded over it!...... A small flashlight run over the pass before you put the next one down is a smart thing to do.  It is amazing how much visible crap is left because the welder just goes to the next location without looking.
Reply:All depends on the tech and his interpretation of what he sees on the scope. Same goes for x ray it all depends on what the Lv2 or 3 determines how the indications fit into the acceptance. I myself firmly believe in UT. But like it was said before they both have their place. Computerized radiography and digital radiography is said to be where xray is headed but they better step aside for advanced UT like phased array. Any method is only as good as the tech and the person reading the data. I have never personally seen couplant cause corrosion on SS. In the refinery and chem plants I rarely wipe couplant off that's mostly 300 and 400 series SS.  We use ultragel, sono 600 and some sono 1100 for thickness. Mostly ultragel for flaw detection. Sent from my XT1058 using TapatalkLast edited by Letzgoracin301; 03-30-2014 at 10:46 PM.
Reply:It seems as if the x ray is missing the lack of fusion whereas the UT is picking it up.  The Oil company is having us UT and X ray all joints anyways so they are being double checked.  Its not like there are lots of failures anyways 5-6 joints out of like 300.The joints with issues get completely cut out, and redone.  No repairs.  One of the ones they cut out they couldn't find any flaws as they re beveled.  It welded up and passed fine second time around.Journeyman / Red Seal Welder (What a useless test)Miller CST 280Miller XMT 350Miller 12vs XtremeEvolution Evo 28 mag drillEvolution 380 Dry Cut saw
Reply:As people already pointed out both methods have their advantages and disadvantages. UT is more sensitive to planar flaws compared to RT.Last week we did a new PQR where we lack of fusion between the third and second TIG pass was found in the macro. Due to the orientation of the flaw and the thickness of the pipe nothing was apparent in the RT. I will upload the macro pic later. You will be amazed when you see the flaw and the fact that the X-ray was perfectly clean. You say you perform UT on duplex. Due to the different phases found in duplex steels UT interpretation can be quite challenging. A calibration block from the same material has to be used and a very experienced operator. Even then in big thicknesses it is almost impossible to obtain useful results in duplex or even austenitic steels.So it does not surprise me not to find during repair a defect shown by UT in a duplex pipe.
Reply:[QUOTE=taz00;3978731..... Even then in big thicknesses it is almost impossible to obtain useful results in duplex or even austenitic steels.So it does not surprise me not to find during repair a defect shown by UT in a duplex pipe.[/QUOTE]Just to comment on this.  Was on a 9% nickel tank job where apparently they had software that sent UT results to head office and the insurance company.  I was following the automatics doing stick pickups/repairs.  Consensus was that if in doubt, take it out.  Testers would mark an area and give a depth.  Going at it with a grinder, I would only notice about 50% of the marked defects.
Reply:Here is the macro I was talking about.Pipe thickness is 17mm
Reply:What was film density? B wire or shim pene? Also what shot technique and film speed? Sent from my XT1058 using Tapatalk
Reply:Technique was double wall and film probably D5. Penetrameter was FEEN (wire), can't remember the exact value or IQI. I will have to check the RT report when I get back to the office on Wednesday for more details such as source type, density etc.
Reply:UT generally find's almost everything, partiuclary if it's a spider clamp UT machine (takes operator error out of the equation).I'm surprised that the client isn't requesting Gamma testing, as it's 99% as accurate as UT, but much faster, in Aus, X-ray is only used for up to 6mm wall thickness, beyond that X-ray isn't accurate enough to be reliable.Last edited by ttoks; 04-01-2014 at 05:52 PM.
Reply:These might help Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Spider clamp UT? Please elaborate. Sent from my XT1058 using Tapatalk
Reply:From my experience customers like xray because they have film in their hand or a disk and they can look at it. UT such as PA you can show them the print out but still isn't the same. Sent from my XT1058 using Tapatalk
Reply:X ray shows it all we ut first fix ut then xray NY Dot never throws out x rays and only a handfull of people can ut their work.
Reply:Originally Posted by Letzgoracin301Spider clamp UT? Please elaborate. Sent from my XT1058 using Tapatalk
Reply:this is almost similar to the ones i've used, but not quite.
Reply:They both have there place and one does not replace the other.  They are complementary.  Both are volumetric inspection techniques.  Depending upon the tightness of the defect and the orientation of it, RT may miss it completely.  UT on the other hand can actually see things that are not there.  So on really critical joints both are done.  In many instances it is usually one or the other. If I could only use one technique, I would opt for UT, and assume what is shown is a flaw even though it may not be, and do the fracture mechanic base on the assumption it is a flaw and go on from there.
Reply:Originally Posted by taz00Technique was double wall and film probably D5. Penetrameter was FEEN (wire), can't remember the exact value or IQI. I will have to check the RT report when I get back to the office on Wednesday for more details such as source type, density etc.
Reply:Interesting I believe it though. Sent from my XT1058 using Tapatalk