Paint rust and weld

[Adam]

You probably have small pin holes in the weld which don't get paint in them, thus making it rust slightly from the inside out. Just a though.

When they do structural welding at work they use some kind of special process to X-ray the welds and check them for porosity and strength.

[CumminsJeep]

You probably have small pin holes in the weld which don't get paint in them, thus making it rust slightly from the inside out. Just a though.

When they do structural welding at work they use some kind of special process to X-ray the welds and check them for porosity and strength.

oooo sounds fancy, but makes sense

[Tom]

probably to do with the welding process. i would go with oxygen in the bead.

[ninetysix-ex-jay]

You probably have small pin holes in the weld which don't get paint in them, thus making it rust slightly from the inside out. Just a though.

When they do structural welding at work they use some kind of special process to X-ray the welds and check them for porosity and strength.

Di penetrate testing. It shows all the stresses and holes you can't see with your eyes. Then they ultrasound the weld which shows any voids made by slag.

[stinky]

ultrasound blows, ive seen weldements get UT'd and fail, then the EXACT part gets x-rayed and have no inclusions...UT's tricky, and in untrained hands, can cost a company non-required repairs of perfectly sound welds...the case here is probably moisture around the weld nugget, rapid heating will cause the surrounding metal to, well, "sweat", pulling internal moisture to surface, and with insufficient heat, stay on the surface... ive encountered the problem before, NUMEROUS times...try heating it with a pro-PAIN torch before you prime it, you'll be able to see the moisture coming out of the metal once the heat hits it...

remember, primer holds moisture, bad too...so dont leave it primed and let the elements hit it before you paint it...

if it was porosity, the paint would fill the voids...and not just oxygen causes porosity, nitrogen and hydrogen cause it too...oxygens the least of your worries and sometimes it can be used in conjunction with argon, such as a 98/2 mix...

Adam: what kinda structural welding does your work do?? usually structural shit doesnt get x-rayed... x-ray tests are $$$$$$$....

[stinky]

haha little technical, but understand how it works, and you'll be set

thank you welding degree!! haha

[Adam]

ultrasound blows, ive seen weldements get UT'd and fail, then the EXACT part gets x-rayed and have no inclusions...UT's tricky, and in untrained hands, can cost a company non-required repairs of perfectly sound welds...the case here is probably moisture around the weld nugget, rapid heating will cause the surrounding metal to, well, "sweat", pulling internal moisture to surface, and with insufficient heat, stay on the surface... ive encountered the problem before, NUMEROUS times...try heating it with a pro-PAIN torch before you prime it, you'll be able to see the moisture coming out of the metal once the heat hits it...

remember, primer holds moisture, bad too...so dont leave it primed and let the elements hit it before you paint it...

if it was porosity, the paint would fill the voids...and not just oxygen causes porosity, nitrogen and hydrogen cause it too...oxygens the least of your worries and sometimes it can be used in conjunction with argon, such as a 98/2 mix...

Adam: what kinda structural welding does your work do?? usually structural shit doesnt get x-rayed... x-ray tests are $$$$$$$....

Everything. There are portable 110 machines up welders the size of a small room with more switches and controls than a cockpit. The last time I was talking to the welders they were adding a section of high pressure steam pipe that is like 2' in diameter.

[Riot]

I thought this was an ode to joe nitro. lawl

[Chaos]

[Ktmracer419]

http://www.naxja.org/forum/showthread.php?t=989480

[stinky]

Everything. There are portable 110 machines up welders the size of a small room with more switches and controls than a cockpit. The last time I was talking to the welders they were adding a section of high pressure steam pipe that is like 2' in diameter.

ya, usually high pressure joints get x-rayed, that and anything super crucial..when i took my cert test, they x-rayed em, i did structural, but the kids that did the pipe test, theirs got x-rayed as well... its pretty much a fool-proof way to non destructively test weld joints, but its $$$$$$$$

[stinky]

http://www.naxja.org/forum/showthread.php?t=989480

my vote is poor prep work....