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Welding over porosity

Posted: Wed Jun 04, 2014 12:42 am
by DylanWelds
I've been practicing for a 6GR today at work, supposed to take it tomorrow, but i noticed that at the stops of my 7018 welds I get some porosity. It's not visible until I hit it with a grinder. Can I weld over this and burn it out without it giving me problems or does each stop have to be grinder clean before restarting?

Re: Welding over porosity

Posted: Wed Jun 04, 2014 7:35 am
by weldin mike 27
Hey,

It all depends on how the joint will be tested, visual only, you might get away with it (MIGHT) If its an xray, or a destructive test, its a big no no.

If its just on your rod re starts, Jody shows a good technique in his videos, where he lights up about 1" in front of the start, and then races the rod back to the end of the weld, and continues as normal. The weld burns out any junk from the restart.

Mick

Re: Welding over porosity

Posted: Wed Jun 04, 2014 8:18 am
by Shield Arc
I think you better figure out what is causing this! I take it as your 7018 is right out of an oven? But you say this is only at the stops? That is strange. :? I got a gut feeling you're long arcing the 7018.

Re: Welding over porosity

Posted: Wed Jun 04, 2014 11:00 am
by DylanWelds
I think i may have been long arcing. I swapped out my lens and can see a little clearer now. I've just got one more pass on my cap to make waiting for it to cool down. No pores today. And yes the 7018 was right out of the oven

Re: Welding over porosity

Posted: Wed Jun 04, 2014 7:15 pm
by Otto Nobedder
"Breaking" the arc on 7018 is the chief cause of porosity on stops. The "burning" flux provides your shielding gas, and pulling back to break the arc exposes the "stop" to atmosphere. Always grind stops when the test is critical.

Steve S

Re: Welding over porosity

Posted: Wed Jun 04, 2014 8:04 pm
by DylanWelds
Thanks guys. Passed the visual just gotta be bent now. I'm feeling pretty confident about it passing, this will be my first actual cert besides the AWS ones I got out of school. Pretty damn excited :D

Re: Welding over porosity

Posted: Wed Jun 04, 2014 8:08 pm
by Shield Arc
A 6-GR is a nice feather in your cap. Good luck! Image

Re: Welding over porosity

Posted: Wed Jun 04, 2014 9:59 pm
by DylanWelds
Thanks! I wasn't expecting it. They let me do some practicing yesterday in the shop and I thought I was just doing a 6G on the bench. I looked it up online and it seems like there's a lot of different 6gr tests. This one they brought a box in and I had to tack the coupon 1 foot from the wall and 1 foot from the ceiling. Got gnarly burns from the box so hopefully they pay off haha

Re: Welding over porosity

Posted: Sun Jun 29, 2014 2:39 pm
by Bubbster
I was havin this issue. I think it's because as I stopped I was pulling the rod straight away from the weld (long arcing). I started ending by running gently up the bevel and it fixed the problem.


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