Pickling Stainless welds

[mash rookie]

I have been doing a little more stainless welding lately. I have been making some ferule reducers and columns. I don’t mind grinding and polishing but some of the welds with the TIG are pretty damn sweet except for the black discoloration.

I tried Muratic acid first. An overnight soak at 50% solution dulled the stainless and removed some but not all of the black discoloration.

After a few Google searches, I purchased some Citric acid from our pals at Duda Diesel. The recipe I found said the material needs to be heated to 150 degrees. I will mix up a slurry and paint some on before placing it in a warm area.

If anybody has ideas, I am open to suggestions and will report my success or failure with Citric acid.

Thanks,
MR

[Ateliervie]

Bradford Derustit "wonder gel" works very well. Expensive, plus a hazardous materials shipping fee. But worth it.

[johnhopper1957]

Mechanical or chemical will work, commercial pickling gel works well, rub it with stainless steel scrubbers or sandpaper will also clean it up nicely. A linisher will get it looking like it hasn't even been joined if you are keen or if you have access to a lathe .

Never tried the citric acid before, sounds like a lot of work and I am a lazy ......

Edit: as soon as you finish your last run on the weld hit it with a stainless brush while it is still hot and she'll come up sweet, removes the discoloration in a flash.

[mash rookie]

Mechanical or chemical will work, commercial pickling gel works well, rub it with stainless steel scrubbers or sandpaper will also clean it up nicely. A linisher will get it looking like it hasn't even been joined if you are keen or if you have access to a lathe .

Never tried the citric acid before, sounds like a lot of work and I am a lazy ......

Edit: as soon as you finish your last run on the weld hit it with a stainless brush while it is still hot and she'll come up sweet, removes the discoloration in a flash.

Thanks, JohnHopper. I will try to wire brush when hot. You may be on to something working hot. The acid is supposed to be used hot. Grinding and polishing is not tough but you can not always take the weld down that far or get into every corner. I have a small sand blaster too. I am looking for the lazy way. Soak in acid and have it come out clean. I will let you know how the acid works. I have not tried using anti splatter on stainless. It may make for cleaner welds. I have found that you can make cleaner welds with a MIG when using it. It acts like more shielding gas when burning off.

[Frosteecat]

Have you tried Naval Jelly?

[johnhopper1957]

No not anti splatter, pickling gel is nitric acid based totally different product. Pickling gel is acid on steroids, it will eat your skin and if you inhale it you will feel your nasal hair getting ready to fall out and you will feel the fumes eating your sinuses out

That said it works really well at cleaning stainless steel ......

[Ateliervie]

To add on to what johnhopper said, the "wonder gel" is some seriously hazardous stuff. It has both nitric and hydrofluoric acid. Both of these acids are a serious danger; wear protective clothing, a respirator, safety glasses, and gloves when handling; and make sure there is plenty of ventilation in the work area.

[mash rookie]

To add on to what johnhopper said, the "wonder gel" is some seriously hazardous stuff. It has both nitric and hydrofluoric acid. Both of these acids are a serious danger; wear protective clothing, a respirator, safety glasses, and gloves when handling; and make sure there is plenty of ventilation in the work area.

Thanks Ateliervie. I missed your post when I responded to Johnhoper. I will try wire brushing hot and the citric acid hot first. If it doesn’t work I will find some "wonder gel"

Hydrofluoric acid is nothing to screw with. 20+ years ago I was a contractor doing fire damage repair. A mason had told me that Hydrofluoric acid would remove smoke damage from a brick fire place. I stopped in the local chemical supplier and asked for some. The guy gave me a funny look and asked if I knew what it was. I said "stronger than hydrochloric?" He would not sell it to me. He explained that it was not just a strong acid, it had other characteristics. He said if you got some directly on your hand it would penetrate your skin and eat your bones. Scared the crap out of me. We bought a sand blaster.

[heartcut]

One of the most horrible things I've ever experienced was in 1979, listening to a craftsman scream while being treated for HF exposure- got a little aerosol from a leak on his neck. They gave him calcium shots to give the HF something else to eat, but it didn't work. The sefety people told us 3 drops of pure HF anywhere on your body, untreated, was a death sentence.

[johnhopper1957]

The easiest option and the safest is to hit it while hot with a stainless brush then if needed stainless steel wool and sandpaper. Commercial welding shops use special belt Sanders that have a belt under spring tension that wrap around the tube as you apply pressure. They are used for all the stainless handrails you see in shopping centers. They are about $300 Australian, I have thought about buying one but not really worth it in my opinion. Putting it in a lathe and wrapping sandpaper sound it willvdo the same thing. If you fuse and don't use filler you can get a weld you can hardly see anyway.

[astronomical]

My brother worked in a hydrofluoric acid plant...

It gets in you blood stream and depletes all the calcium in your body and kills you.. Its true that 3 drops will kill you... I would avoid dealing with it at all costs...

[mash rookie]

Scary stuff. My girlfriend and I talked about it yesterday. She is an ER nurse. She has never seen a case of HF exposure but remembers studying it and said the treatment was massive amounts of calcium. She promptly forbid me from using it.
I welded up a 4 x 2 reducer yesterday. A simple job once a circle of 1/8" stainless is cut and sized. After welding the disc onto the 2" ferule I took the time to hit the weld with a die grinder before welding it onto the 4". That weld was on exterior and was easy to grind clean and flush on my belt sander.
I mixed about 2 cups of citric acid with 2 quarts of warm water. I put two fittings in and placed them in a warm location near my glass furnace. I should learn something today. If temp plays a factor I may try boiling fittings in a citric solution.

[Frosteecat]

Here's a forum with how to use citric acid to descale espresso machines, but it gives some info and procedures for what I think you're after:
http://www.home-barista.com/espresso-ma ... 15778.html

[mash rookie]

Thanks Frosty. It confirms that citric acid performance is better at higher temps. My parts were cleaner this morning with much of the heat discoloration gone but not the black on the actual weld bead. I topped it off with warm water and left it. I will see what it looks like tomorrow. I am soaking them in an old cooking pan that would easily set on top of my propane burner for boiling. I think I will be patient on these, then try the boil method on freshly welded pieces for comparison. Outside of course. Standing up wind.

[Dnderhead]

if your weld is black something is not right..not enough gas/to much gas/wrong gas/to hot /puling filler out of shielding gas/trying to go to fast?

[mash rookie]

if your weld is black something is not right..not enough gas/to much gas/wrong gas/to hot /puling filler out of shielding gas/trying to go to fast?

Interesting remarks Dunder. It makes sense that the black is burned metal. The only way to burn metal is to allow oxygen to be present. I don’t get “shinny” welds with my MIG either. The only time I remember ever having shinny stainless welds was years ago stick welding. They were damn pretty after the slag was chipped off.

I am using a standard welding gas mix with the TIG. Argon/CO2. I have a hotter stainless tri mix with helium that I use when MIG welding stainless but it doesn’t seen necessary with the TIG. You get so much penetration already that a hotter gas is not necessary.

You have me thinking that I am not running enough gas or my technique is wrong. I will definitely try some changes. I am self taught with the TIG. I weld like a MIG with it, pushing the weld as opposed to pulling a weld like stick welding. If I try pulling the weld maybe shielding gas will stay on the hot surface a second or two longer preventing the metal burn.

If my assumption is correct I should be able to solve this. Maybe even welding inside a purge box? Is welding gas lighter or heavier than air?

Okay, I gotta ask. Who the hell are you and how did you get so freaking smart?

Oh, and thank you.

[johnhopper1957]

I think this is where interpritation comes into it, one person says black, another says discoloration, another says dark marks on the weld site and all three people can be talking about the same thing. You will get what I call "discoloration".

You want to form your weld pool and push into the weld pool, if you use filler (I wouldn't if you are just joining two fittings, I would fuse them) keep the filler rod just in front of the pool and dab it in. Another technique I like but you won't get the stack of dimes look is to just lay the filler rod on the join and run over it with the torch. You can get the stacking effect by manipulating the torch if you want and keeping the correct torch angle.

If you don't have ample shielding gas flow you will see what looks like soot and burn marks on your job, you may also hear the tungsten "burning" you will also see a imperfection in your arc and it will just look "wrong" (you will know what I mean if you see it) Once you finish your run have your post flow gas running for 3 seconds if fusing 1.6mm wall stainless and keep it over the weld pool to prevent cratering.

Pure argon is the best option, argon and CO2 is popular because it is cheaper, I have never tried it but have been told not to....

You don't want a purge box - don't look to deep

[mash rookie]

You are right JH. After considering Dunders post I went out to the shop and tried a few changes. More gas, less gas, push the puddle, pull the puddle, anti splatter. No difference. The same dark weld.

Your description is exactly how I weld. The beauty and ease of a TIG is being able to fuse. It has taken me awhile to get used to how much penetration you get with a TIG. After blowing through a few things that I thought I was just fusing the surface opened my eyes. I have used the laid rod trick and got a pretty good dime stack with the right pattern.
Generally, if I have a project where I need any significant amount of filler I change over my MIG to stainless wire and the helium gas. Although I did a considerable amount of gas torch welding as a kid and it is similar, steady feeding with a TIG where you can not pull the flame back will take more practice.
My unit is a low duty cycle AC/DC and the control is on the gun. I try to find the correct heat and go.

JH, does straight Argon work better with stainless? My helium mix is expensive. I just want to use the best.

[johnhopper1957]

At training institutions they use straight argon with stainless, family member has a multi million dollar engineering business and he uses straight Argon on Stainless (his TIG specialist does high preasure steel pipe welding, first run with TIG using Argon then a second run over the top of that with MIG), welding shop I have been "hanging out at / doing a few jobs" uses straight argon.

I have asked a few fellas who weld for a living about the argon / CO2 mix to try and save a few dollars and they have all said stay away from it and spend the extra on straight argon. I have thought about trying Argon / CO2 but am thinking if what I am doing now works why potentially go to something that will cause problems? Might as well stick with a good thing, is it really worth the potential stuff around for $20.00 a bottle?

As for other mixtures like helium they are for specialised welding tasks, your only doing stainless tube for a still No-one is going to be xraying the welds and we're not welding aircraft parts

With your penetration have a play with your torch angle and you will be suprised at the difference you can achieve....

[mash rookie]

I use a pretty good angle just so I can see the puddle. I am guessing you get more penetration at perpendicular. Or maybe it acts like a torch putting heat out front when angled. Damn it John give up info when you suggest things. I have a fresh bottle of the helium tri mix but will try straight argon next time my mild steel gas runs out. The helium works well with a MIG on stainless. There are so many combinations and styles. I consider myself a real good amateur when welding. Closer to pro status with torches. There is not much I cant do with them. They have their own limitations. I have only had the TIG a couple of years and still learning that baby. It sure is sweet for some jobs. I gave away my stick welder to my shop guy after not touching it for ten years.

[Oxbo Rene]

I've always used just straight argon tigging stainless.
Now, I have on rare occasion, got a bad bottle of gas ....................
Can you recall that your welds were a lot better looking in the past,
but now they look different? == something's wrong...................

A pic would be nice ..........

[Dnderhead]

its been years since iv tig.but it seems that CO2 or mixes with CO2 is not recommended for stainless because of the carbon.

[johnhopper1957]

Try more angle so it is getting more away from perpendicular, you will get less penetration - you don't need full penetration. Depending on your welder you can change settings to get a wider weld pool as well which doesn't hurt. Given the strength of stainless steel and what we are using it for you don't need to have it stand up to hundreds of PSI. You just need to get it sealed, if you have 1.2 mm to 1.4 mm of penetration on 1.6 mm wall you have a VERY strong join and a nice finish on the inside, no perosity and it just needs a rub with a bit of sanpaper and it is sweet as.

With copper it doesn't matter if you get penetration as you will just end up with a nice bead on the inside, you also don't need the post gas flow as it won't crater. If you get any undercut throw a bit of filler on it and "smooth it in" and you won't even see it.

I agree with the photo comment, have you got a photo of a weld before it's cleaned up?

[mash rookie]

Okay, I am feeling a little foolish. I do three different processes and only have two welding bottles. I MIG mild steel and stainless. I TIG. I exchange for whatever gas I need and at some point had traded my argon for tri mix. Yesterday I took my empty weld gas to the welding store. The guys know me well after years of working with me. When I asked them about argon they started laughing and chiding me asking what hell am I doing using anything but argon with the TIG. They said my cocker spaniel should know better and by the way why was she not with me? The argon welded a little cleaner on stainless but is the colder of the three gasses. Here is a pic. It will clean up easier.

[johnhopper1957]

Looks good to me, once you clean that up it will look nice

We all do silly things like that occasionally, I have two TIG torches attached to two different TIG welders, occasionally I pick up the wrong torch and when nothing happens I think to myself "the soloniod hasn't kicked in, no gas flow and no HF kicking in, I hope the welders not stuffed" then I look at the torch and think what an idiot I am......... pick up the other torch and it works lol

[Oxbo Rene]

Circular wire brush (fine) on a drill motor should polish her up real nice ................

Sometimes I'll make one of them "pipe" belt buckles (cut 2" SS pipe @ 45 degree =.25" thick slice)
cut that in half, flip one side over and weld back. Twist up some 1/16th rod (one ends in vise, other ends in drill motor),
cut em to fit inside = weld.
Make hook and belt keeper = weld on ...
Then take ruge (sp) and buffing wheel on big grinder =polish up to mirror shine.......

[XFABCALGARY]

hey just a few comments some has been covered...

that black you are seeing is called carbide precipitation or "sugaring" (major weld fault) your weld should be salmon color then shiny rainbows after a wire wheel. for type 304 being 18% chromium and 8% nickel "18-8" try and find a low carbon 308L filler rod 1/16 use 2% Thoriated tungsten . you NEED 100% argon or helium gas for gtaw of any kind . 100 percent inert gas is required to protect your tungsten and the weld puddle. get a gas lens and swap out your tigs collet body, it improves shielding gas coverage and joint accessibility so you can stick your tungsten out way farther for better visibility also requires less gas flow = cheaper to run. use no chemicals! a $20 6" stainless steel wire wheel on a makita 905b grinder spinning at 10k rpm will polish your nice welds no grinding required. turn your heat down and travel slower, if you keep your butt weld tight you dont need to back purge as you will not get full pen on gauge metal below 70 amps you are just going for a seal weld anyway. use just enough amps dc electrode neg to wet out edges, if you want a nicer bead run a slight groove in your butt joint with a 1/16 zip cut on your right angle die grinder or open your joint 1/64 it allows the filler someplace to go. always sharpen tungsten to a sharp point the same angle as a pencil elongated (3:1 length:diameter) and make sure the grinding grain goes length wise with the tungsten not with the circumference. always travel forehand "push" 10-15 degrees and keep your torch at half the included angle of the joint on a butt weld 90* on a lap joint or fillet weld 45*

just a few thoughts but practice with these procedures and things will work better.

[Dnderhead]

looks more like i remember..like distilling patience is something needed with TIG.

[mash rookie]

Wow. That is some beautiful looking work. Damn. Thanks for the input. I am humbled. You give me something to strive for. I love this forum.

[XFABCALGARY]

Wow. That is some beautiful looking work. Damn. Thanks for the input. I am humbled. You give me something to strive for. I love this forum.

cheers

here is what i would do on a flange like what you have pictured. fit it up how you want "square, level, plum, flush or CORNER TO CORNER" and have 4 tacks 90* apart quartering the flange. now split the distance between each tack with another tack criss-crossing like you would tightening a tire. start each tack like this... 1 establish arc 2 build puddle 3 add filler 4 manipulate torch in tiny figure eights to wash the puddle out to edges 5 stop. once you have gone around a few times and have equal 3/4 to 1 inch distances between tacks all the way around take a minute and let the heat dissipate evenly. a key to minimizing your distortion is plenty of tacks and spreading the heat all around. next start to weld from one tack to the next then jump across the flange to the next spot again continue in a criss-cross manner. the truth is you don't even have to weld continuously from one tack to the next! tig is wonderful you can stop/start any where you want. just put one tack on top of the first then stop, then another tack on top of the second then stop, again another tack on top of the third, again tack on top of the previous, continue like this from one tack to the next then jump. this equals the beginning of dime on dime stacks and helps you to learn manipulation of the puddle. and hey thanks for the compliments but it is like anything once you do it 100 times you get good

Regards R