Recently certified, trying to prep for test. Need help.

jsanchez · Sun Oct 11, 2015 4:56 pm

Hello, I'm new to the forum. So I received a structural, pipe and combination certifications in mid May of this year. I'm currently working at a company that needs a welder and wants me to test on structural. They are giving me time to prepare. The test consists of 1/2" plate open v groove. 1/16" gap. using 3/32" 7018. In 2g, 3g and 4g. I was also told that after I weld it all the way out I would turn it around, grind out the slag from the back and put one more pass on the back where the root is. Now in school I had always done my root passes with a 6010. But here its with 7018 and i just cant seem to get it to work for me. I tried running with no land, I tried running with a 1/16" land to match the gap size. But I just can't seem to get it to work. I also tried just running a straight stringer and also tried weaving and holding about a second per side. The metal seems just drop and make big nasty looking bumps and it comes out really uneven, and not to mention not much penetration. Ir un at about 75-80 amps. Any help or advice is appreciated.

Poland308 · Sun Oct 11, 2015 6:34 pm

Is there a max limit on the land?

jsanchez · Sun Oct 11, 2015 7:07 pm

Poland308 wrote:Is there a max limit on the land?

As far as i know, there is no max on the land. Do you think i should add a bigger land?

Poland308 · Sun Oct 11, 2015 9:46 pm

Might help.

Shield Arc · Sun Oct 11, 2015 9:51 pm

Try a heavy 1/16" to 5/64-inch land, use a 5/64-inch drill bit for the gap. 3/32-inch 7018 run on DCEN about 65 to 70-amps for the root.

jsanchez · Sun Oct 11, 2015 10:08 pm

Shield Arc wrote:Try a heavy 1/16" to 5/64-inch land, use a 5/64-inch drill bit for the gap. 3/32-inch 7018 run on DCEN about 65 to 70-amps for the root.

Ok so maybe run my heat a little colder. and a slightly bigger land. But DCEN? seriously? Is that allowed? And will that cause me to fail an xray in any way?

Shield Arc · Sun Oct 11, 2015 10:19 pm

Yes seriously! Unless you have a WPS stating to only run DCEP. DCEN will help prevent burn through. I don’t see how running on DCEN would fail an xray.

jsanchez · Sun Oct 11, 2015 10:29 pm

Shield Arc wrote:Yes seriously! Unless you have a WPS stating to only run DCEP. DCEN will help prevent burn through. I don’t see how running on DCEN would fail an xray.

Alright, well ill give it a shot tomorrow after work. Ill report back with results.

Poland308 · Sun Oct 11, 2015 10:33 pm

: image.jpeg (63.81 KiB) Viewed 1086 times

I recently had to do some reading on rods do to my making a less than informed comment on the topic.

Shield Arc · Sun Oct 11, 2015 10:35 pm

Try my joint prep, but also try it on DCEP. You may like it better on DCEP.

jsanchez · Sun Oct 11, 2015 10:48 pm

Poland308 wrote:
image.jpeg
I recently had to do some reading on rods do to my making a less than informed comment on the topic.

Yeah i have some miller calculators and the stick amperage calculator tells me that 7018 should only be run on DCEP. Im just gonna change the fit up and run colder i think. Then turn it up after ive set in my root.

Shield Arc wrote:Try my joint prep, but also try it on DCEP. You may like it better on DCEP.

Ill try the joint prep on Both.

noddybrian · Mon Oct 12, 2015 3:54 am

I've not kept up with certs as I don't do enough to justify the retest fees anymore - but the WPS we used for single sided V groove on boiler / pressure vessel was 7018 root to cap & the root was always done electrode negative - maybe worth a try depending on the rods - over here virtually all rods are + / - .

Owr · Mon Oct 12, 2015 4:03 pm

With that diameter of rod and plate thickness you shouldn`t of have too much problem. You just have to solve amp and landing settings which is a bit of trial and error. Machine settings can vary though, can`t say that what works on on one, works on all.

Since you will be able to grind the back side, will it be inspected first or just turn and grind? If just turn and grind then even if the root ain`t joined perfect, the slag will most likely not be trappped anywhere. Just make sure you let it cool before second pass if they give you unlimited time to prevent sinking of root pass from the back. When the gap is closing use a cutting wheel slightly thinner than what the gap should be (again, if they allow it).

I had to pass a test with 1/8 on 10mm plate open root with no amp control - it ain`t easy thats for sure, so much heat build up.

Practice makes perfect, if you passed cert then you are skilled no doubt `bout it.