tube weld inspection

[Razzmyth]

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?

Thanks,
Darryl

[wronghand]

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.

[Razzmyth]

Thanks for the reply.

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

[Paul Seaman]

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!

Peace,
Paul

[Razzmyth]

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

[On fire most of the time]

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!