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tube weld inspection

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  • tube weld inspection

    Hey guys,

    I’m new to this forum, hoping you guys can help.
    I work for a race series in Canada where individuals can fabricate and weld their own roll cages. So the cage builder may or may not be a professional welder.
    In the past we only asked the following with respect to welding.

    Guidance on welding:
    All welding must be of the highest possible quality with full penetration and preferably using a gas shielded arc. They must be carried out along the whole perimeter of the tube. Although good external appearance of a weld does not necessarily guarantee its quality, poor looking welds are never a sign of good workmanship.

    So our only method for checking quality of welding is by visual inspection.

    I’m looking at possibly having the cage builder submit a sample of their welding to a professional inspection facility to ensure that the builder knows how to do proper welds. I know this doesn’t ensure that all welds on the cage are done right, but it’s a step forward in ensuring the cages are better built.

    The sample would be two pieces of 1.75"x.095" ERW or DOM mild steel tubing welded in a T shape.

    What I need to know is what kind of inspection should be done to ensure that this sample piece is properly welded?


  • #2
    Short of destructive testing? I would say a Mag-Particle test would be a good starting point.
    For a destructive test maybe two tube intersections (to form a cross, 2 tubes-- one coped into either side of a parent tube) so that a tensile test may be performed.

    Sonic testing and/or x-ray may be valid tests as well-- AWS 17 (aerospace) consists of 2- 1 1/8" tubes (have to be at least .063" wall thick.) butt welded in the 6G position. It's an x-ray test.
    Last edited by wronghand; 03-31-2011, 08:58 PM.
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    • #3
      Thanks for the reply.

      I'm thinking that a tension test may be the way to go.


      • #4
        A penetrant test kit with UV lamp and a set of glasses would run you a couple hundred bucks and do a fine job on the road or at track testing. Other than that requiring a person to do a sample on site and certify the person as opposed to the particular piece.

        Visual has always been acceptable on the majority of offroad series that I am aware of since the most prevalent participants are average ordinary guys with weekend exposure.

        Open wheel racing on the otherhand has a different deal since the G force loads and such endanger spectators they generally have high percentages of the car x-ray certified.

        These are two extreme ends of the racing gammut, where yours falls only you can decide. I would say a visual and then any conspicuous welds do a penetrant test on, the later being strictly a pass or fail!



        • #5
          thanks, I'll do some reading on UV penetrant testing.


          • #6
            For your reading pleasure, you might also pick up a copy of the SCCA and/or NASA tech inspection sheets. You may also have a better response on either of those websites when it comes to inspecting cages as well.

            One thing we (the shop I used to work for) always looked for was a cold weld. If you saw boogers, grind marks, saggy welds, or just looked plain cold, it was party time with a grinder.

            Hopefully you find what you are looking for, best of luck on staying safe!
            Precision is only as important as the project...if you're building a rocket ship...1/64" would matter. If you're building a 1/8" probably wont.


            • #7
              I too am involved in a racing organization and am involved in the making and policing of the rules(head tech). We were informed many years ago by attorneys to be very careful about how we mandated/policed things such as roll cages, safety harness',and such. We only "recommend" as to avoid being sued for not protecting them against themselves. By having welders submit their work to be inspected if there is a catastrophic failure, a slick attorney will grab the case and will sue any one involved.


              • #8
                thanks for the reply.
                Our rules specify certian FIA standards. This helps with the liability issue.