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Questions about welding stainless

PostPosted: Fri Apr 02, 2021 8:12 pm
by bluc
For any boilermakers on here

When welding stainless can I use stainless wire in a mig then passivate with hot citric acid solution and is it a complex process to do it correctly.

Or plan b if i back purge how is this done do I need to seal the vessel and fill to a certain pressure or how is the correct amount of purging gas achieved?

Re: Questions about welding stainless

PostPosted: Fri Apr 02, 2021 8:43 pm
by RuddyCrazy
To passivate SS after welding just go buy some stuff from a welding supply store and use a brush to apply the paste etc, now with purging one needs an outlet to expel the air from the vessel and if one doesn't have a second bottle for purging then a Tee piece off the argon supply can do for the purging and supply the mig or tig with argon too by simply increasing the flow. Now with purging it will also weld the inside where NOT purging will cause the inside of the weld to sugar or plain and simply put crap on which needs to be ground off.

Mig welding with SS wire can be tricky but using higher amps and wire speed and thus a quicker feed can give good results. Bang for buck personally I prefer tig to mig as it gives a much stronger weld and a huge better finish.

Re: Questions about welding stainless

PostPosted: Fri Apr 02, 2021 8:56 pm
by bluc
Thanks ruddy :handgestures-thumbupleft:

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 12:01 pm
by LikkerSheWillLoveIt
I hate MIG welding. It’s not as fast as TIG welding when you look at the entire process.

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 1:25 pm
by howard
i can't weld, but when i was looking around for some possible work on my boiler i found this.
can it be that different with non-purge/purge welds?

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 2:23 pm
by RC Al
LikkerSheWillLoveIt wrote:I hate MIG welding. It’s not as fast as TIG welding when you look at the entire process.

Please expand on that?
Ive always felt Migs are like a hot glue gun...

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 2:33 pm
by RuddyCrazy
I had a play with my 309 SS wire in my Viper 181 mig with some scrap SS of the kegs and noway could I get a good enough weld to what I did tig welding. 309 is great for second SS and is a good dissimilar metal for welding different metals but where a tig can used on everything bar ferrous material where a mig is great. By using high amps and a quick wire speed good flat welds are the norm where when using tig EVERYTHING has to be spotless :angry-banghead:

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 5:14 pm
by LikkerSheWillLoveIt
Without sounding arrogant, If you can TIG weld, there is far less cleaning up, less grinding, no spatter, a far more precise weld with a TIG, I don’t even polish half of my welds. Hard to get a weld like this on thin material with a spaghetti gun, if this was to be sanded and polished, it would have taken me 5 minutes, wouldn’t happen with a MIG.

Let’s face it, none of us are welding over 3mm thick stainless for a still. TIG not MIG.

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 5:32 pm
by RuddyCrazy
Eh Likker is that copper as it sure looks like it, now when I've tig welded copper with my old tig that went out in style it took 100 amps just to get a puddle going, now with my new welder less than 20 amps does the same job and for doing a 90 degree weld like that picture what I found when I've done it by leaving one section about 2-3mm over the edge acts as the filler rod and the result comes out like a radius :handgestures-thumbupleft: With using tig on copper if one has a neat clean joint by using lower amps and working quickly one doesn't even need a filler rod.

For welding pipe work I have an old faceplate setup where I can just turn easily to work around the pipe when welding and with a totally clean joint and neat fit no filler rod is needed.

Now mate I'm not trying to tell how to suck apples but it's just the way I have learnt and I aint done no trade school with welding either, just watch a few old tradies do their craft and learnt from there :handgestures-thumbupleft:

Cheers Bryan

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 6:49 pm
by bluc
LikkerSheWillLoveIt wrote:Without sounding arrogant, If you can TIG weld, there is far less cleaning up, less grinding, no spatter, a far more precise weld with a TIG, I don’t even polish half of my welds. Hard to get a weld like this on thin material with a spaghetti gun, if this was to be sanded and polished, it would have taken me 5 minutes, wouldn’t happen with a MIG.

Let’s face it, none of us are welding over 3mm thick stainless for a still. TIG not MIG.

I have never tigged is it. Lot harder then oxy?
May be easier if I just pay soneone but with this hobby I see lots potential use.

Re: Questions about welding stainless

PostPosted: Sat Apr 03, 2021 9:07 pm
by Dude
bluc wrote:
LikkerSheWillLoveIt wrote:Without sounding arrogant, If you can TIG weld, there is far less cleaning up, less grinding, no spatter, a far more precise weld with a TIG, I don’t even polish half of my welds. Hard to get a weld like this on thin material with a spaghetti gun, if this was to be sanded and polished, it would have taken me 5 minutes, wouldn’t happen with a MIG.

Let’s face it, none of us are welding over 3mm thick stainless for a still. TIG not MIG.

I have never tigged is it. Lot harder then oxy?
May be easier if I just pay soneone but with this hobby I see lots potential use.



Its not that hard bluc, if you can gas weld you should be ok. If you are interested in getting a tig you are more than welcome to drop in to brissie and have a go with mine.

Re: Questions about welding stainless

PostPosted: Sun Apr 04, 2021 8:53 am
by LikkerSheWillLoveIt
RuddyCrazy wrote:Eh Likker is that copper as it sure looks like it, now when I've tig welded copper with my old tig that went out in style it took 100 amps just to get a puddle going, now with my new welder less than 20 amps does the same job and for doing a 90 degree weld like that picture what I found when I've done it by leaving one section about 2-3mm over the edge acts as the filler rod and the result comes out like a radius :handgestures-thumbupleft: With using tig on copper if one has a neat clean joint by using lower amps and working quickly one doesn't even need a filler rod.

For welding pipe work I have an old faceplate setup where I can just turn easily to work around the pipe when welding and with a totally clean joint and neat fit no filler rod is needed.

Now mate I'm not trying to tell how to suck apples but it's just the way I have learnt and I aint done no trade school with welding either, just watch a few old tradies do their craft and learnt from there :handgestures-thumbupleft:

Cheers Bryan



That is stainless, 2mm wall thickness. I never overlap, if a weld needs wire I add wire. I fuse a lot of joins for the purpose of building stills, always purge weld. I’ve been doing this 15 years and I currently build robots.

Re: Questions about welding stainless

PostPosted: Sun Apr 04, 2021 9:01 am
by LikkerSheWillLoveIt
bluc wrote:
LikkerSheWillLoveIt wrote:Without sounding arrogant, If you can TIG weld, there is far less cleaning up, less grinding, no spatter, a far more precise weld with a TIG, I don’t even polish half of my welds. Hard to get a weld like this on thin material with a spaghetti gun, if this was to be sanded and polished, it would have taken me 5 minutes, wouldn’t happen with a MIG.

Let’s face it, none of us are welding over 3mm thick stainless for a still. TIG not MIG.

I have never tigged is it. Lot harder then oxy?
May be easier if I just pay soneone but with this hobby I see lots potential use.



There’s a lot more control with a TIG. It takes a little while to get the hang of it, but like anything, it takes a lot of time, practice and the occasional tantrum to get proficient, even longer to get good. I have fixed many an item that “my mate said he could weld” that’s taken 10 times longer to fix, than it would have taken me to do it right the first time. It’s a great skill to have, that is for certain. My back doesn’t agree any longer though.

Re: Questions about welding stainless

PostPosted: Sun Apr 04, 2021 12:56 pm
by bluc
LikkerSheWillLoveIt wrote:
RuddyCrazy wrote:Eh Likker is that copper as it sure looks like it, now when I've tig welded copper with my old tig that went out in style it took 100 amps just to get a puddle going, now with my new welder less than 20 amps does the same job and for doing a 90 degree weld like that picture what I found when I've done it by leaving one section about 2-3mm over the edge acts as the filler rod and the result comes out like a radius :handgestures-thumbupleft: With using tig on copper if one has a neat clean joint by using lower amps and working quickly one doesn't even need a filler rod.

For welding pipe work I have an old faceplate setup where I can just turn easily to work around the pipe when welding and with a totally clean joint and neat fit no filler rod is needed.

Now mate I'm not trying to tell how to suck apples but it's just the way I have learnt and I aint done no trade school with welding either, just watch a few old tradies do their craft and learnt from there :handgestures-thumbupleft:

Cheers Bryan



That is stainless, 2mm wall thickness. I never overlap, if a weld needs wire I add wire. I fuse a lot of joins for the purpose of building stills, always purge weld. I’ve been doing this 15 years and I currently build robots.

When back purging whats best way to make a dam especially once the keg needs to be inverted during welding..

Re: Questions about welding stainless

PostPosted: Sun Apr 04, 2021 1:57 pm
by LikkerSheWillLoveIt
Duct tape is you best friend! If you are welding a keg, don’t bother trying to fill the entire thing with argon. That’s 4:30 minutes of constant gas at 11Lpm just to fill it, before welding.

Re: Questions about welding stainless

PostPosted: Sun Apr 04, 2021 5:15 pm
by scythe
Just fill the keg with water to reduce the volume of gas you need for back purging.
Just don't wet the area your going to be welding to minimise the chance of porosity.

Re: Questions about welding stainless

PostPosted: Mon Apr 05, 2021 7:23 am
by LikkerSheWillLoveIt
scythe wrote:Just fill the keg with water to reduce the volume of gas you need for back purging.
Just don't wet the area your going to be welding to minimise the chance of porosity.


Great way to limit gas needed!

Re: Questions about welding stainless

PostPosted: Tue Apr 06, 2021 7:59 pm
by B-Man
scythe wrote:Just fill the keg with water to reduce the volume of gas you need for back purging.
Just don't wet the area your going to be welding to minimise the chance of porosity.


I wish i saw this when I was tigging up my keg. it still sugared on the inside and used a heap of gas :angry-banghead:

Re: Questions about welding stainless

PostPosted: Mon May 31, 2021 7:29 pm
by bluc
Decided i will grab a tig in a few weeks. Looking at the trade tools 15a renegade brand one.
Also looking at a plasma cutter. Anyone have any experience with the renegade brand plasma cutter?

Re: Questions about welding stainless

PostPosted: Mon May 31, 2021 7:51 pm
by LikkerSheWillLoveIt
I’ve typed this 3 times. So I’ll make it short.

Yep. Good.

Tradetools had a Unimig welding bundle sale in the email on Friday.