[ONDGAS]

Hi guys,
Ive attached some pics, ive encountered this a couple times and im not sure if its contaminants or a shielding problem,
I have a #8 gas lense and 3/32 thoriated 2% electrode on these welds and it just turns to crap. Basically the job is a set of mild steel headers, i can be welding away and everything is roses and then all of a sudden its like as if someone has turned my gas off.
I have whipped the die grinder out and ground the welds back and even acetone wiped it and whilst it did help it still fizzles and bubbles up. What can cause this?

I should add that half the steel is from a different exhaust shop and is aluminized...and while this def did bring up crap in the puddle when i welded these pics are not of this aluminized steel tube. i dont have a mig so i had to tig these up and the areas on the pipe to pipe that i welded (not the pipe to flange) i ground flat and rewelded where ever it looked suspicious and everything is smothed out now so im hoping they will hold up fine.

Any ideas?

[kiwi2wheels]

Have you been using this 2% on other jobs with no worries or is this the first usage ? Have you tried it on some material that you know welds OK with no problem ?

You're not welding over something that was previously MIG'd ?

Just for shits and grins, try another tungsten, from another packet, even a different grade that is OK for DC. If that's not an option, try another 2% from the pack you have.

Edit ; you're not getting an intermittent draft that's blowing your gas shield away ? Is the fan on your machine on constantly or on demand ?

[AndersK]

Three things
No matter what tungsten type you use will give this problem.

The yellow dust in first pic tells me you have zinc coating involved.

I got similar issues recently. Some good some with awful bubbling. Had been lazy and used one of my die grinders that has a front exhaust, tiny drops of oil at random spots....

[exnailpounder]

That brown stuff is just "glass" from the silicon in your filler floating out crap. The worst of it looks like a gas problem to me. You never said what your cfh was...too much is as bad as too little....looks like you might be drawing in some air somewhere. If you were welding metal impregnated with zinc, you wouldn't have any decent looking weld. Zinc is a nightmare. It blows up and bubbles and spits and craps up your tungsten.

[Poland308]

Yup yellow crap is from the zinc coat. Other possibilities might be that the steel tube is of inferior quality and it may have junk embedded in it. Especially if it's close to an area that was bent.

[ONDGAS]

kiwi2wheels
I dont think its the electrode because.... I have used it before, i made up the whole set of pipes with two electrodes from the same pack and 90% of the welds were fine, a couple days ago i bought a new pack of 2% from a diff supplier (reputable) and these pics are the result.

Poland308
im leaning towards there just being crap in the steel as i know when i was a apprentice the pipe is packed with all sorts of stuff for stopping rust and shit, it was fine for a mig but maybe tig isnt liking it, i would have went stainless but its a friends car and he bought a kit to make up headers so im just working with what i have-story of my life.

exnailpounder
i run 16cfh, i thought maybe when i was welding inside the header flange in the above pic that because it was on a sharp corner maybe the sheilding gas was getting diverted and thats why it was bubbling, i cranked it up to 19cfh and still no good.


So these pipes are really tight in the engine bay so when i started making them i bolted the header flange to the engine and had to cut the first bends on a angle so the pipes were out of round, hence why its so messy inside the flange, the plan was to weld the pipe to flange and then go crazy with the diegrinder to smooth it all out, this is where i opened up a can of worms because i then thought i could weld inside so that the weld would really smooth and mold it together to be almost seamless.... wow was i wrong, ive given up now and it is what it is.

Can i also say that every once in a while i would get this problem with the pipe to pipe joins and it was just intermittent, when it happens it would start to blunt up my tungsten and i could see crap form on the tip...no i didnt touch the tungsten, its all most like it did a star trek "beam me up scotty" from the work piece to my electrode and stuff my day up.

Im pretty new to tig and by new i mean hopeless so im sort of going in blind, this is why we ground smooth all the welds on the pipe so it looks abit better as my welds dont look great, but where it did bubble up i found giving it a grind and hitting it with a bit of a puddle and adding somefiller made it come good...but not in the original pics i posted

[dave powelson]

From the 3rd pic posted--porosity all around outside, porosity on the inside.
Appears the outside flange plate and it's ID saw little to no clean/sand/prep--oil residue.
Rough plasma cut flange hole can hold all kinds of stuff in the cut edge.
A spec of oil, just a pencil dot size, can expand when vaporized to say 1,500X the original volume,
making for great, BIG, gas bubbles.
Keeping the tube ID and OD free of oil, bright and shiny is all part of the deal. Clean gloves, too.
Good prep takes a fraction of the time and hassle to deal with the results of bad prep.
If porosity rears it's head--it's easier to stop and redo than soldier on as you did.

Getting aluminized down to bright and no coating imbedded, then sanding and cleaning...
I've used muriatic acid to strip it, the fumes are nasty, but it works.

Disregard for thorough prep and the resulting mess, seems to be a Rite of Passage for
many. It's a great learning experience to profit by, on the next go-around.

[exnailpounder]

I wasn't aware your new at tig. Welding round pipe has it's own challenges because you get out of position so fast. Maybe when your torch angle changes, you are drawing in air and getting the porosity. Getting in a good position and doing a dry run can really help you keep a correct torch angle and arc length. If you think you have a contamination problem, it wouldn't hurt to heat the ends of your pipe with a propane torch before you weld to try to boil out any crud. You don't need to get it cherry red, just good and hot. Like others have alluded to...you can't ever have your metal too clean for tigging. Alot of problems that people come here to help get resolved are contamination related but I can see a few other issues as well. It looks like your welding a little cold but it's hard to tell from the pics but I honestly think you are just getting out of position quickly and ending up with a bad torch angle and/or too long of an arc length and things are going south. I say that because you have a good bead for a short time and them wham. Positioning and doing dry runs is very important. Watch Jody...you will see him do dry runs all the time.

[ONDGAS]

thanks for that,

Yeah well i do find it hard to rig on pipe, especially such small pipes, and the flange sections were a bitch because it exaggerated the torch angle problem, some times its just straight up hard to get in there with the torch on the right angle.

eg. if there is a 90deg bend i can do the top half of the bend pretty well but the bottom forces me to have the torch at 45deg to the thick flange, and my technique for welding think to thin at the moment is to hit the thick bit with some big amps and melt "into" the thin pipe. i dunno if thats the pro way to do it but thats my backyard style of getting it done at the moment.

I should have taken pics while still unground so you guys could give me some tips but i have to make up the rest of the exhaust so i might do it then although thank god that will be stainless i seem to have more success with stainless

i appreciate the help guys

[cj737]

thanks for that,
I should have taken pics while still unground so you guys could give me some tips but i have to make up the rest of the exhaust so i might do it then although thank god that will be stainless i seem to have more success with stainless

i appreciate the help guys

If you are welding up a stainless exhaust, purge it while welding. It matters in the long run. If your fit up is good enough, you won't even need filler.

[ONDGAS]

Thats actually made me remember something i was busting to ask...
Last time i did a stainless pipe i did purge, i gave it a minute to fill with gas before i started and yet there was still a few parts that were sugary around the weld, I put it down to either i didn't give it long enough to fill or the fact that what i was welding was 4" pipe.....maybe it simply wasn't enough of a purge line to fill it up.

Also at some point you end up welding a nearly completed exhaust which can be 5-6 feet of pipe...how the hell do you get all the way around a weld while still keeping it angled and all the while by yourself and keeping a good torch angle. in the end i put it flat on the ground turned up the purge and just hoped

[exnailpounder]

Thats actually made me remember something i was busting to ask...
Last time i did a stainless pipe i did purge, i gave it a minute to fill with gas before i started and yet there was still a few parts that were sugary around the weld, I put it down to either i didn't give it long enough to fill or the fact that what i was welding was 4" pipe.....maybe it simply wasn't enough of a purge line to fill it up.

Also at some point you end up welding a nearly completed exhaust which can be 5-6 feet of pipe...how the hell do you get all the way around a weld while still keeping it angled and all the while by yourself and keeping a good torch angle. in the end i put it flat on the ground turned up the purge and just hoped

Argon is heavier than air so you have to position your pipe so the argon fills from the bottom and forces the air out the top. It takes longer to purge something than you might think. You need to tape them up good and let the gas keep running as you're welding and that's tricky because your burning the tape off with the heat. Time to get creative. Maybe a flex-head torch or some other style....or just mig them.

[Oscar]

Argon is heavier than air so you have to position your pipe so the argon fills from the bottom and forces the air out the top. It takes longer to purge something than you might think. .

The reason it takes longer than one might think, is that the argon while initially denser than the air, it is really just a matter of time as it inter-mixes with the air. Argon cannot stay separated from the air it is displacing, for if it could, it would separate on it's own in our own atmosphere, yet it doesn't. It is the same reason argon does not "settle" in a tank of 75/25 argon/CO2 mig gas. All gas molecules are always shooting around randomly at all times, when it comes to welding gases.

[ONDGAS]

The reason it takes longer than one might think, is that the argon while initially denser than the air, it is really just a matter of time as it inter-mixes with the air. Argon cannot stay separated from the air it is displacing, for if it could, it would separate on it's own in our own atmosphere, yet it doesn't. It is the same reason argon does not "settle" in a tank of 75/25 argon/CO2 mig gas. All gas molecules are always shooting around randomly at all times, when it comes to welding gases.[/quote]

Sooooooo then one may ask how do you properly purge pipe if there is still air in it?

[exnailpounder]

The reason it takes longer than one might think, is that the argon while initially denser than the air, it is really just a matter of time as it inter-mixes with the air. Argon cannot stay separated from the air it is displacing, for if it could, it would separate on it's own in our own atmosphere, yet it doesn't. It is the same reason argon does not "settle" in a tank of 75/25 argon/CO2 mig gas. All gas molecules are always shooting around randomly at all times, when it comes to welding gases.

Sooooooo then one may ask how do you properly purge pipe if there is still air in it?[/quote]
Gotta keep that gas flowing all the time you're welding.

[Poland308]

We've discussed this a bit before. You do need to fill whatever your purging at a slow rate to keep the gasses from swirling togeather. But Argon will stratify even in an open top vessel. This is why purge boxes work, and why some people suffocate while welding in open trenches or tanks.

[exnailpounder]

Argon is heavier than air so you have to position your pipe so the argon fills from the bottom and forces the air out the top. It takes longer to purge something than you might think. .

The reason it takes longer than one might think, is that the argon while initially denser than the air, it is really just a matter of time as it inter-mixes with the air. Argon cannot stay separated from the air it is displacing, for if it could, it would separate on it's own in our own atmosphere, yet it doesn't. It is the same reason argon does not "settle" in a tank of 75/25 argon/CO2 mig gas. All gas molecules are always shooting around randomly at all times, when it comes to welding gases.

Back in my cave diving days...guys diving tri-mix, and even nitrox would roll their bottles on the ground with the notion that they were re-mixing the gases that had separated. One guy went so far as to build a turntable for double tanks. My friend was a nuke tech on a submarine and he told me there was a little something to that whole gas separation thing but nothing to worry about. Guys would re-analyze their tri-mix bottles if they had been sitting for awhile with the notion that helium atoms would permeate the steel tank walls. I was never sure if I was getting my leg pulled or not.

[Oscar]

The reason it takes longer than one might think, is that the argon while initially denser than the air, it is really just a matter of time as it inter-mixes with the air. Argon cannot stay separated from the air it is displacing, for if it could, it would separate on it's own in our own atmosphere, yet it doesn't. It is the same reason argon does not "settle" in a tank of 75/25 argon/CO2 mig gas. All gas molecules are always shooting around randomly at all times, when it comes to welding gases.

Sooooooo then one may ask how do you properly purge pipe if there is still air in it?

Eventually you do end up pushing out most all the air with a proper purge setup, so it's just a matter of time. Of course you lose some of your purge argon at the same time, but that's the nature of the beast. You have to envision that while yes your argon purge is pushing out air at the other end of your purge setup, the argon feeding into the space has already initially begun to mix just a little bit with the air as their is no invisible barrier that will prevent them from doing so. But you definitely can't calculate it solely based on the CFH flow of the purge flow and the internal volume of the space being purged. This is why there exists O2 purge monitors----you can see in real-time how much % or parts-per-million you still have of O2 within your purge volume. If it were as easy as a straight-forward calculation to know when you're at 100% argon, purge monitors wouldn't exist.

We've discussed this a bit before. You do need to fill whatever your purging at a slow rate to keep the gasses from swirling togeather. But Argon will stratify even in an open top vessel. This is why purge boxes work, and why some people suffocate while welding in open trenches or tanks.

I do believe that to be correct, just not what I was getting at. The mixture will always be there initially, there will just be less and less of it as time goes by because the welding gas is being pumped in at a greater pressure than atmospheric pressure. I was just trying to emphasize the "time" factor. but perhaps I worded it incorrectly. Sorry if I confused anyone. I should stop posting right before my bedtime or during my lunch break, lol.

[Poland308]

There is truth to the helium leaking through the steel tank walls. I once worked on an old tank that was used to store helium. They were decommissioning it. We had to grind off the tags and stamp info. When they did the paper work associated with the vessel i was talking to an engineer about it. He said in there operation they monitor the loss rate through the tank walls. But they measured the loss rate in grams over a year period.

[exnailpounder]

There is truth to the helium leaking through the steel tank walls. I once worked on an old tank that was used to store helium. They were decommissioning it. We had to grind off the tags and stamp info. When they did the paper work associated with the vessel i was talking to an engineer about it. He said in there operation they monitor the loss rate through the tank walls. But they measured the loss rate in grams over a year period.

Grams of of weight for gas can translate to a huge amount of loss. People wonder why their tires go low with no holes or damage...the oxygen molecules are permeating the rubber...nitrogen too but not as fast. Fascinating stuff.

[LtBadd]

Sooooooo then one may ask how do you properly purge pipe if there is still air in it?

You can make a purge plug that will allow you to purge a much smaller area then a 5ft length of pipe/tube.
Make a plug that is a little bigger then the ID so it will go in with a little force, this way you know it will stay in place and not fall over. You can push the plug to within 10" or so of the weld, thus greatly reducing the volume you need to purge

Image1.jpg (20.72 KiB) Viewed 887 times

Here is a simple plug I made recently to purge an internal volume using aluminum foil.

20170413_184350.jpg (34.23 KiB) Viewed 887 times

[ONDGAS]

I never put a brass filter on my purge line like you did In the above pic, would this be a problem? I would think it's going to fill the enclosed space your purging regardless so is it needed?

[Otto Nobedder]

I never put a brass filter on my purge line like you did In the above pic, would this be a problem? I would think it's going to fill the enclosed space your purging regardless so is it needed?

A brass muffler like this does a wonderful job of diffusing the purge gas, rather than injecting it. Yes, there's a difference.

Steve S

[LtBadd]

I've been using those for years, as Steve said, it does a great job.