[DanW]

Hi guys,

another noob question,

I'm practicing for the 3G test in stick, open root

currently I've finished the root pass, and 3 passes ontop of that, have a few more passes before i can do the cap. the instructor has got me grinding each pass perfectly flat, all the way down until there are not little marks anywhere on the weld surface- completely smooth bare metal before each pass

it seems like i'm just welding a pass on, and then grinding it off completely, and then putting another on etc and not getting anywhere quickly..

The reason he said to do it is because it will be x-rayed and the tiny little holes and gouges that reveal themselves while grinding down will be picked up on the x-ray

So i guess my question to you is, in the field how are these welds done properly without having to grind to completely bare flat metal each pass? surely in the field you would just be welding beads next to existing beads after slag removal etc? seems kind of strange to spend so long grinding out each weld and reducing it to the point where i'm depositing 1mm of metal per pass and requiring 6 or 7 passes to fill the joint lol

hopefully i've not been too confusing. i've been told to use a weaving technique for each pass not multiple beads as well

[kermdawg]

The reason he said to do it is because it will be x-rayed and the tiny little holes and gouges that reveal themselves while grinding down will be picked up on the x-ray

This is true. Obviously the goal is not to have said voids or inclusions in the weld. That being said, it does seem a little counter productive to grind so much just to pass an x-ray. The goal is to produce welds without voids/inclusions without having to grind between every pass.

What I'm trying to say, is a little grinding is part of welding. But if your grinding down every pass your probably doing something wrong.

Also, producing x-ray quality welds isn't something that you can do overnight. X-ray quality welds are the best of the best. I appluad your instructor for wanting to make you the best you can be. You must have really impressed your instructor if he's having you turn out x-ray quality welds dude.

[DanW]

thanks again kermdog,

its not so much inclusions and holes that i'm finding in the middle of the bead after grinding away a bit, but say along the edges where it meets the plate, each ripple on the edge of the bead might cause a tiny little pocket i guess? or say a little shelf where after grinding theres a distinction between the top of the ripple you've just ground, and the edge of the plate?

anyway i've been grinding everything out so the gap is filled by a completely seamless, shiny collection of weld, no longer recognisable as a bead. maybe i'm going overboard and maybe if i just ran a weld over the edges of the last bead, the ripples and distinctions between the previous bead and plate would just melt together thus removing the need to grind them smooth

i'll try take a photo next time, i have a feeling i've been over grinding and the instructor is all for it because i guess it's a guarantee lol

cheers
Dan

[jpence38]

That's all the instructor wants is for you to pass. Believe it or not, in those tiny little spaces along the edge of the weld you can miss a tiny piece of slag stuck in there and that won't be good. I remember years ago when I took my 3G (all 7018) that the instructor did the same thing. I didn't grind so much of the middle though. Running vertical up will most likely burn any little bits of slag or pockets back out of that edge, but on a test it's better to be safe than sorry. Try to hang on the edge just a tad bit more and you can eliminate the pockets that can hold slag in them. By the way are you testing on plate or pipe?

[kermdawg]

Jpence is right, when your doing the pass over the top, you should be burning out any slag left over on the edges, where the bead meets the plate/pipe. Thats why its oh so important to have enough heat to burn that stuff out, but not to much so you get undercut. Its all about findin the right balance man.

[DanW]

Thanks for replies,

That's how the instructor put it, but I guess I was confused as to how much overkill this would be in the field- before I grind it down I'm whire wheeling and getting all the visible slag out, its just any ridges caused by where the ripples meet the edge of the bevel, the instructor is having me grind out so as to not trap slag in the next pass

My thinking was that in the field you'd be wanting to run the stick hot enough as kermdawg says to melt away the little pockets or ridges before trapping any slag in them, but for the purposes of passing an x-ray test well i'm not complaining

i'm running the test on plate, open root with a landing, did the root pass with 7016 and the rest with 7018. the root pass penetrated well on my 2nd go with no undercut or lack of fusion that i or the instructor could see (first plate i messed up big time and decided instead of trying to salvage it, to spend the rest of the day practicing the fill and cap passes and start with a fresh plate the next day)

on the fill runs i'm doing currently i'm using a 1-2 pause on each side and a medium paced weave from side to side, i'm watching the edge of the bevel and when I see it melt away a little (little circular gouge the shape of the electrode) i wait until the filler metal fills that up again to avoid undercut then moving at a medium pace to the next side and so on.

i reckon the stick is really fun but i kind of want to move on to MIG and TIG so i can start getting some qualifications toward aluminium boat building/repair

[4m welder]

yep, it sucks but you gotta be a good grinder first! Make your movements kinda slow...7018 does not like to be disturbed so to speak. Hold on the corner until you see it tie-in and keep bouncing...if your bead is humping up, don't spend alot of time in the middle..you'll see that puddle pull into the corners..that's good...just stay in front...slag inclusions mean more grinding and I can tell you it ain't fun grinding down a couple of passes! Have fun

[welder57]

being certified to API 1104 code i have to re-certify every 6 months on 6" steel in the 6G position. however my sample isn't xrayed, its done with what they call destructive testing which is a little more stringent than say an xray from what i'm told . i've only completed probably 30 xrays with 1 failure and it was slag inclusions that went o/s the parameters of the code. i use 6010 rod and i grind completely the root pass so the center of that weld isn't humped up. now there are what they call wagon tracks along both sides which can be ground out also but if your hot pass is hot enough you'll see those tracks float right out of there. now i do grind every start and stop on every pass but the cap. remember to run hot, when you lean towards the cold side, surely you'll have failures, i think your trainer is trying to eliminate any possible problems so go with what he says. upon certification you can experiment as to what works best for you. one thing i find with welding is that talk to everyone you can. you'll find you learn something new every time out.