Porosity and dirty looking welds driving me crazy!

[adamp]

I recently purchased a power arc 160 sth with the foot pedal from Everlast Canada, and am having a huge issue with my welds that I'm hoping somebody can help me with...no matter what I do it seems, about 8 out of every 10 beads I run have porosity and end up looking contaminated around the edges. Sometimes if I let the welder sit, then try another weld an hour later, the first bead comes out beautiful! Then I start getting browned edges, flaking/grey on top of the weld, and porosity. Here's what I've tried so far;

-Checked lines for leaks by pressurizing, and then shutting off the tank and leaving it for 15 minutes or so. Found a very small leak on hose connection to flow meter/regulator, and tightened it. Leak is gone, problem still there.

-took the torch apart and found that the hose clamp on the torch end for the gas was slightly loose. Replaced clamp and connection is now tight.

-Checked torch hose for leaks by dunking in water and blowing through hose, couldn't find anything.

-Checked all connections with soapy water while system was pressurized. Nothing.

-Swapped over to a bigger (#8) cup.

-Checked that torch assembly was air tight by blowing into cup with everything tightened. Seems good.

It seems as if somehow, air is being drawn in, or something is contaminated. All testing was done on 1/4" steel plate, ground to shiny, clean metal. 3/32 E3 tungsten (purple band) and 15cfh indoors with no wind. I thought maybe my flow meter was reading incorrectly so I even borrowed a gas flow tester that goes on the end of the torch and found the gauge is off a bit. 11LPM (about 22 Cfh) on the flow meter is actually putting out 15 Cfh at the torch.

The only thing I can think to do is maybe try a new tank of argon? Called the welding supply and they said it should be a good batch of gas because I'm the only one who's called about it. I've also only welded about 4 hours maybe and already used almost 3/4 of the tank. I'm not sure the exact size but it's about 3 feet tall to the top of the valve, so a fairly large tank.

Any ideas?!?! Thanks for reading!

Adam


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[joshuab]

You seem to have been pretty thorough in your testing. If you have access to another tank of gas, it certainly wouldn't hurt to test it out. Some gas companies will say anything to get you to go away...

EDIT: A cylinder that is 31" x 7" holds 80 cf. At a flow rate of 15 cfh, you should have nominally 5.33 hours of welding time. In reality, your number will be somewhat lower than this due to post-flow, but it's a starting point. Frankly, it's hard to tell how much arc time you actually have unless you've got an arc timer. Bottom line is, if you have verified no leaks and you have verified your flow rate, the gas consumption is whatever it is. Confirm when you pick it up that the regulator reads the correct PSI for a full tank, which, in my experience is somewhere between 1800 and 2200 psi, depending on how full your gas supplier decides they are going to make them.

[adamp]

Thanks for the reply joshuab! Sounds like I'm not using more gas than what is normal for the size of tank I have. I think I'm going to go in and see if the supplier won't swap the tank out for a new one. Guys there are usually pretty good to deal with so hopefully it's not a hassle. Fingers crossed it works, Im going insane over here!


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[Rambozo]

How much tungsten stickout are you running? That's the only other thing that comes to mind. Are you new to TIG in general?

[joshuab]

I re-read your original post and noticed you mentioned browned edges. A brown/orange, rust-colored halo around the bead is often a sign of contaminated tungsten. With all the care you're taking, surely you're grinding your tungstens fresh, but it makes me wonder if they're contaminated somehow. Usually, that's caused by dipping the tungsten in the puddle and then continuing to weld without re-grinding. Could it be that your grinding wheel is contaminating the tungstens somehow? I've heard people say that you shouldn't grind tungsten on a wheel that's been used for steel, but I've also heard other folks say that there's not much chance of soft steel getting embedded in the hard tungsten. I dunno... what if you got a fresh grinding disk for your angle grinder and ground a tungsten and tried again? (I only say angle grinder because it's a lot easier to grab a fresh angle grinder disk than it is to go buy a new bench grinder wheel.) Maybe turn the tungsten around and grind the "back" end of the tungsten that has never been touched yet. Just fishing for possibilities here...

[adamp]

How much tungsten stickout are you running? That's the only other thing that comes to mind. Are you new to TIG in general?

I'm just finishing up a 7 month welding level C program here in British Columbia, but am pretty new to tig. Have done a bit in class but mostly SMAW, GMAW, and FCAW. Stick out is about 3/16" to 1/4". I usually just keep the ground tip of the tungsten sticking past the end of the cup.


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[joshuab]

I'm just finishing up a 7 month welding level C program here in British Columbia, but am pretty new to tig. Have done a bit in class but mostly SMAW, GMAW, and FCAW. Stick out is about 3/16" to 1/4". I usually just keep the ground tip of the tungsten sticking past the end of the cup.

I'm not qualified to judge for myself, but I have welded under the tutelage of those who say that 1/8" is the max stickout unless you're using a gas lens. I use a gas lens exclusively, so I'm not sure how much wiggle room there is in that. Realistically, I don't think that a mere 3/16" to 1/4" would cause such severe problems like you're having, but for what it's worth, another thing to try. If that same stickout is working for you in class, no reason it shouldn't work for you at home, unless maybe class is running gas lenses.

[youngnstudly]

First off, if you're making practice beads on steel, I would loose that #8 cup and put something smaller on. If you were welding something critical that you were worried about discoloration with, then I would install a bigger cup/gas lens. I would wipe everything down with acetone just for the sake of saying you did, extend that tungsten out 3/8" past the cup, and try again. The only time I use 1/8" stickout is when I am welding aluminum.

If your arc length is too long, that can be a contributing factor (and it's not all that uncommon for noobies to do), and too little stickout can make it really tough to see what's going on with a big cup blocking your view of the arc, which means you have to pull away and create more arc length. For steel, I use 3/8" stickout for the more common joints, and more stickout (usually with a gas lens) for tight areas.

Just to give you an idea, I almost never weld with more than 7 or 8 LPM on my home projects (trying to get more MPG), I use "just enough" and adjust post flow accordingly, and I will "fine tune" from there by swapping cup sizes, increasing/decreasing stickout, increasing/decreasing post flow, and installing/removing the gas lens (again, depending on what material I'm welding). Too much LPM is just as troublesome as too little, and bigger cups use more gas.

With the smaller cup (say #5 or #6...if you have one) and the 3/8" stickout, I would start low with the regulator setting, like 5 or 6LPM, and slowly increase (until your problem clears up) to no more than about 10LPM (if you find that you even need that much). I even use a #4 cup during times when my cylinder is almost out (and I'm right in the middle of welding something that I want to finish!), so that I don't chance getting porosity from the lack of gas flow. I'm not welding on bridges or terribly critical items most of the time, and I find that my method works fine a majority of my projects. Go from one extreme to the other in situations like this and it will help you better visualize what's going wrong, what you need to do to fix the issue, and what to look for when things do begin to go wrong.

Make sure you're running electrode negative too! Simple and easy mistake if you're not paying attention, or you were stick welding with reverse polarity and forgot to change back. ER70S-6 (or S-2) in no bigger than 1/8" diameter would be my starting point, with 3/32" being preferred. You find that you'll want to keep a wide selection of consumables on hand for odd jobs and such, but just starting out with TIG doesn't always allow you to make additional purchases for such items ($$$).

Good luck!

[joshuab]

The only time I use 1/8" stickout is when I am welding aluminum.

That's a good point. The guy who was teaching me was teaching me on aluminum. See? Shows what I know...

[adamp]

I re-read your original post and noticed you mentioned browned edges. A brown/orange, rust-colored halo around the bead is often a sign of contaminated tungsten. With all the care you're taking, surely you're grinding your tungstens fresh, but it makes me wonder if they're contaminated somehow. Usually, that's caused by dipping the tungsten in the puddle and then continuing to weld without re-grinding. Could it be that your grinding wheel is contaminating the tungstens somehow? I've heard people say that you shouldn't grind tungsten on a wheel that's been used for steel, but I've also heard other folks say that there's not much chance of soft steel getting embedded in the hard tungsten. I dunno... what if you got a fresh grinding disk for your angle grinder and ground a tungsten and tried again? (I only say angle grinder because it's a lot easier to grab a fresh angle grinder disk than it is to go buy a new bench grinder wheel.) Maybe turn the tungsten around and grind the "back" end of the tungsten that has never been touched yet. Just fishing for possibilities here...

I thought of the tungsten being contaminated as well, so I grabbed a fresh one and ground it on a brand new fresh wheel. Still acting up unfortunately...hopefully this bottle change today makes a difference. Has anyone used acetone to clean the gas hoses from the bottle to the tank, and from the welder to the torch? Thinking about doing that too..


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[adamp]

I'm not qualified to judge for myself, but I have welded under the tutelage of those who say that 1/8" is the max stickout unless you're using a gas lens. I use a gas lens exclusively, so I'm not sure how much wiggle room there is in that. Realistically, I don't think that a mere 3/16" to 1/4" would cause such severe problems like you're having, but for what it's worth, another thing to try. If that same stickout is working for you in class, no reason it shouldn't work for you at home, unless maybe class is running gas lenses.

I'm not sure if the school uses gas lenses as I was pretty new to it when I tig welded in class. I've got a gas lens, insulator, collet, and a couple of #8 cups on order so I will try that as well. Thanks again for the replies everyone. I'll let you know how this new bottle works!



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[adamp]

Good news! Turns out it was a bad bottle of gas, welding supplier was great and swapped out the bottle no problem. Go figure, first bottle of gas I ever buy is no good. At least I can stop pulling out my hair now!thanks again for the replies everyone!


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[joshuab]

Good news! Turns out it was a bad bottle of gas, welding supplier was great and swapped out the bottle no problem. Go figure, first bottle of gas I ever buy is no good. At least I can stop pulling out my hair now!thanks again for the replies everyone!

Congrats! Shows what, "We haven't had any other complaints," gets ya. For all the other suggestions I made, my money was on bad gas the whole time. Make sure you call them back and let them know you've confirmed the diagnosis.

[Kempy]

Just pick up two bottles of gas today myself and the first thing I do is test it mainly on aluminum it shows the gas if its not 100% Argon steel it not as bad if it is bad I use it for Mig welding just mix a little Co2 with it and it works just fine the welding shop give me a discount on the bottle because I still used it for something else and did not return it. Once they did not believe me so I told them to come and see it weld and to bring a new argon as well they apologized for the mix up. I keep a small 20Cf tank of 100% Argon for testing if the new bottle is bad, it is nice to verify that it is bad and not something else. Once I know the tanks is good I will top up the little tank.