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  • pipe weld X-RAY

    Im not really sure how x-rays work. When the cwi comes to x-ray a weld on a open root pipe joint, can he tell how deep your penetration on your root bead was? I know they can see voids and and if you got both edges of the root face but what about the depth of penatration on the root pass?
    sigpic2007 dodge 3500 cummins

  • #2
    i dont think he can "see" how thick you weld is.
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    • #3
      Non-Destructive Weld Testing

      SAE: Visit www.esabna.com/education/knowledge

      "Radiographic & Ultrasonic Weld Testing"

      Did you find out what they're doing up in Globe with that H2O line?

      Is it part of the US 60 widening project?

      Dave
      "Bonne journe'e mes amis"

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      • #4
        Originally posted by 1428turbo View Post
        i dont think he can "see" how thick you weld is.
        Yes they can tell how thick your weld is and how much penetration or lack of. I x-ray weld boiler tubing and can tell you for sure they can do this.
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        • #5
          Originally posted by davedarragh View Post
          SAE: Visit www.esabna.com/education/knowledge

          "Radiographic & Ultrasonic Weld Testing"

          Did you find out what they're doing up in Globe with that H2O line?

          Is it part of the US 60 widening project?

          Dave
          The company never could tell us what certs we needed to have. And I cant seem to find anyone there that can tell me any useful info, so I think im going to have to find something else. Would have been a nice job but I dont think its going to happen. They are doin a 16 inch three week long job and they only want one welder and one fitter. GOOD LUCK WITH THAT. OH and they dont want rigs.
          sigpic2007 dodge 3500 cummins

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          • #6
            Originally posted by sae350 View Post
            Im not really sure how x-rays work. When the cwi comes to x-ray a weld on a open root pipe joint, can he tell how deep your penetration on your root bead was? I know they can see voids and and if you got both edges of the root face but what about the depth of penatration on the root pass?

            They can see everything that can result in a rejectable weld. So yes, if you have IP or IPD they'll see it and call it. Same with a low bead, burn thru, gas pockets, internal undercut, etc, etc.
            They'll also see indications within the weld like porosity or slag plus they'll see defects on the surface. But those will be caught by visual inspection before RT the vast majority of the time.

            JTMcC.
            Some days you eat the bear. And some days the bear eats you.

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            • #7
              Are you not confident in your welds or just curious? Dave
              Originally posted by sae350 View Post
              Im not really sure how x-rays work. When the cwi comes to x-ray a weld on a open root pipe joint, can he tell how deep your penetration on your root bead was? I know they can see voids and and if you got both edges of the root face but what about the depth of penatration on the root pass?

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              • #8
                Originally posted by 1428turbo View Post
                i dont think he can "see" how thick you weld is.

                Like somebody alreay said, yes they can tell the thickness of the weld deposit.
                Everything that the code calls out as a possible reason for rejection can be seen on RT film.
                As the head NDT man/film auditor for a major pipeline operator once told me when I was on the repair crew "film never lies" Of corse he had to admit that a slightly off center crawler could sometimes throw a "shadow", but film readers (usually) know it when they see it.

                JTMcC.
                Some days you eat the bear. And some days the bear eats you.

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                • #9
                  Originally posted by turbo38t View Post
                  Are you not confident in your welds or just curious? Dave
                  No Im confident. I have passed many of x-rays, but I was cutting apart some old six inch natural gas pipe the other day and was looking at the root passes on the inside of the joints and noticed that in some spots they got good penetration and other spots they got both edges but the bead was flush with the inside of the pipe with no penetration. I just wonderd how it would pass x-ray unless the x-ray didnt so the depth of penetration on the inside.
                  sigpic2007 dodge 3500 cummins

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                  • #10
                    A lot also depends on how well the tech can read the film.I had one tell me once that I had incomplete fusion in one area of the root.I knew it was fine so I just grinded slightly on the cap to make it look like it had been grinded back down to the root and repaired .The weld was re-shot and said it was fine.Like everything thing else there are good techs and there are bad ones.
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                    • #11
                      Originally posted by sae350 View Post
                      No Im confident. I have passed many of x-rays, but I was cutting apart some old six inch natural gas pipe the other day and was looking at the root passes on the inside of the joints and noticed that in some spots they got good penetration and other spots they got both edges but the bead was flush with the inside of the pipe with no penetration. I just wonderd how it would pass x-ray unless the x-ray didnt so the depth of penetration on the inside.
                      I'm no CWI or X-ray tech but I believe most codes require a 1/16 of an inch of ''weld reinforcment'' meaning your root should be 1/16 of an inch tall and your cap should be 1/16th over flush, in a perfect world. Take that at what its worth tho, its probably hear/say or something I read a few years ago. I would imagine if it broke both walls down then its pretty hard to tell ( on film ) if its just flush. An x-ray tech told me once that the tie goes to the runner
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                      • #12
                        "Sonic (not burgers) Testing"

                        When I was in the concrete biz (Kiewitt), sonic testing was used on caisons for quality assurance. For those unfamiliar with caisons (pronounced kay'-zon), an auger bores a hole in planet earth, and is subsequently filled with concrete. They are primarily used for bridge pier and column support. Depth and diameter is predicated on soil composition, seismic values and other geological variables. Some are large, others can be formed in a cluster. After the re-bar "cage" is made, PVC tubes are placed the length (depth) strategically around the perimiter, and once lowered into the hole, these tubes are filled with water. During the pour, after vibrating, inspectors can lower their probes into these tubes to read aggregate seperation and concrete density. Unlike most other concrete pours, there are no forms to "strip," as the form is the hole. Traditional "slump" tests are still taken, and sample cylinders for destructive testing based on mix design.

                        I realize, this is a welder's forum, but there are many parallels in structural CIP (cast-in-place) concrete and steel structure and pipe weldments. These two materials are the principle "building blocks" of the construction industry, and have specific codes. As the AWS governs the welding industry, ACI (American Concrete Institute) certifies inspectors, publishes building code and design requirements, including post-tension and seismic strengthening.

                        Dave
                        "Bonne journe'e mes amis"

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                        • #13
                          there are calibration blocks that are "shot" to tell you what a specific thickness looks like. The reader then compares the thickness with the test specimen.

                          There are different test blocks for the different densities of metals. It is fun to set up and run but reading them is a whole other skill set.

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                          • #14
                            The thing you have to keep in mind with RT is that you are still looking at a 2 dimensional image. You can tell height and length, and different shades of gray. By judging the location an indication in a weld you can "estimate" depth. As far as discerning if a weld has complete penetration, your just looking at contrast differences. The base metal is a constant shade of gray. If the weld is darker than the base metal then it has passed through less material. If the weld is lighter than it has passed through more. That is all the RT person is doing. This is not an exact science, but with experience a tech can give a good estimation.
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                            • #15
                              [QUOTE=hogan;187153] As far as discerning if a weld has complete penetration, your just looking at contrast differences.QUOTE]


                              IP won't show as a "contrast difference", it will show clearly as a bevel that's not been consumed by the bead. An untouched edge of a land is pretty plain to me, not that I've looked at a million films, but these things appear pretty evident in my opinion.
                              A concave bead will show as a contrast difference.
                              Those contrast differences are pretty pronounced, it's easy to see where a bead has pinched down in a narrow spot even tho both bevels have been broken down.

                              JTMcC.
                              Some days you eat the bear. And some days the bear eats you.

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