Welding Tips and Tricks

recenetly my friend had a roll cage built and asked me to have a look at it
i was left spechless, and offered to do a dye pen test to see how bad it really was.

I'd almost bet that was done in or near Slidell, LA. If so, I know who welded it.

Steve

nah this was welded in oz.

whats even better is its chrome moly

Sorry for my ignorance, but what exactly are we looking for with this dye penetrant testing? What are you guys seeing on these welds?
Thanks

All those red spots around the welds are defects (They may be cracks, holes or lack of fusion) in the weld that can lead to failure in the weldment. By the way, don't be sorry. The only way to learn is ask questions, and the only stupid question is the one that doesn't get asked.

WOW! Thanks for the explanation! Was the dye applied from the outside and only adheres where there is a defect? I guess you have to know what you are looking for. It seems like the stuff just pooled up in spots and dried there. It looks like the welder applied a primer or something in the welded area to prevent corrosion. I thought you might need to wire wheel that coating off to get at the welds? Very interesting! I guess i have my work cut out to look into this more. I have more questions! LOL

Okay, so I searched You Tube and found several demonstrations of the process. I now see that what looks like white primer in the photo's is actually the developer spray. That sure seems like a lot of defects! Hard to believe that the dye was cleaned off at all before the developer was applied!
I guess you need considerable experience in most cases to interpret the results? In these photo's it is obvious there are issues though.

Hey there,

Once you understand the process and have an idea about how the dye behaves, and if you have a basic understanding of welding (a lot of Non Destructive Testing techs do not have a welding back ground. I know ones who were a carpenter a plumber and a mechanic before they started) you can see pretty easily whether there are defects or not
You can judge by how dark the mark is how much dye came out and there for how big/deep the defect is. ie: light dye mark= not too deep, very dark or big mark = pretty big defect. This is a good cheap process. Handy to have the stuff laying around in the workshop.

Mick

I understand the dark red spots around the welds and even the heat effected areas, but why is there so much red showing on the pipe itself? That would almost indicate a porosity in the pipe itself would it not?

The pipe is extruded through a die, and the surface has microscopic "defects" across it's entire surface. These are not considered flaws, unless a line shows up. It's simply the "grain" of the metal.

Steve

Good info Steve!
Thanks, I'm learning quite a bit here! Is this type pof inspection covered under Level I Inspection? I think I'd like to take that training through our Canadian Welding Bureau (similar to AWS) soon.

Also depends on how the dye was applied.If the dye was applied real heavy,maybe it was too much left on the test area. If you follow the inst. on the can . wait for the red dye to soak into all voids,usually 10 to 20 min., then I take a clean rag & spray with brake cleaner & wipe the red dye off,till only the imbeded dye remains. Wipe it down again with a clean dry rag.Let that dry by air,not compressed air. That can spread the red dye too much. Then spray on the developer[white] And wait for the developer to dry.When I see large dark areas like I'm seeing in the photo ,maybe too much red was left on. A little red dye goes a long way. Some times I use a que-tip to apply the red dye. Hope this helps R/R