Welding a plate on top of my keg

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Welding a plate on top of my keg

Postby StillDrinkn » Fri May 11, 2018 7:56 pm

I've watched a few instruction videos of tig welding and I'm keen to give it a go. But I might be throwing myself in the deep end...

I've got a keg I cut the top off a while back for my still and was going to use a new keg, but my old one is much nicer looking and in better condition. My only issue is the 210mm wide circle I have cut in it. I was thinking I could weld a flat piece of stainless in, but I'm unsure how to do so without leaving little crevices for nasties to live and how to keep gas against the weld to stop sugaring...

Can someone with a bit of knowledge in this area give me some advice please? I can fusion weld, stick weld and mig weld without issue, so I don't think it's a stretch to weld stainless. I was thinking to tack some tabs on the underside of the lip to hold the plate in place till it's tacked. I can then grind the welds after I cut my 4" hole for my ferrule. I would drill a hole where my element is going to pump argon into the keg.

Doable? Hard? Let me know...

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Re: Welding a plate on top of my keg

Postby coffe addict » Fri May 11, 2018 8:05 pm

It's all doable, it can be stick welded but if you penetrate to the other side it'll be messy on the inside. The nasties aren't really an issue you'll cook them and then steam them in high abv alcohol lol.
If your wanting sanitary welds it gets a lot harder and above my pay grade.
Good luck either way.
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Re: Welding a plate on top of my keg

Postby StillDrinkn » Fri May 11, 2018 11:20 pm

That's along the lines of what I was thinking, but I had also thought that penetration on a butt weld with argon purging the other side, should provide a good weld on both sides, but I'm unsure of the amount of argon to do so. I guess I'll just keep watchong youtube vids and have a good practice run before a get into it...
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Re: Welding a plate on top of my keg

Postby RC Al » Sat May 12, 2018 1:03 am

Just putting this out there as I have not tried it yet
I have been looking at the whole purging thing and came across tape that has a strip of fiberglass running along the middle of it. This is supposed to exclude oxygen from the back of the weld, I dug a bit further on some welding forums and found a lot of people just using masking tape, may be worth some experimentation
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Re: Welding a plate on top of my keg

Postby woodduck » Sat May 12, 2018 10:05 am

I must be missing something with this purging thing. Why is everyone so worried about it? Are you just worried about looks or rust or health problems? I've never purged anything and haven't seen any problems by not doing it but like I said I think I'm missing something.
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Re: Welding a plate on top of my keg

Postby wynnum1 » Sat May 12, 2018 10:55 am

If your doing it on a keg boiler does not have to be sanitary as the heat and alcohol vapor will kill anything .
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Re: Welding a plate on top of my keg

Postby StillDrinkn » Sat May 12, 2018 2:07 pm

[youtube]https://www.youtube.com/watch?v=AIRWMhoke9I[/youtube]
This video should answer your questions regarding gas purging... You could argue that gas isn't required for mig welding also, but we all know the weld is compromised by not using gas.

RC Al can you link me some of this stuff? Not sure if masking the other side would sufficiently shield it from air/seal it for purging? I have also seen welders using plates to remove heat from their welds in a heatsink kind of fashion. Not sure if it's necessary on thinner material. I'm still learning, and will pobably need some practice before I go ahead with it
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Re: Welding a plate on top of my keg

Postby Fishleg » Sat May 12, 2018 3:28 pm

I reckon purging is a waste of gas especially on something as large as a keg. Besides if you have your heat/penetration right you don't really need it. If you're putting so much heat in that you're blowing holes in your base material then you will need it.

:text-+1: on what the others say about it not really mattering with a keg

If you already have a mig you can do it with that too just switch to stainless wire and use your regular 5/2 gas mix. That works ok for me. Although now I have a TIG I mostly use that for stainless.

Also make sure if you're buying a TIG unit get one with high frequency start and a foot controller :handgestures-thumbupleft:
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Re: Welding a plate on top of my keg

Postby StillDrinkn » Sat May 12, 2018 3:51 pm

I plan to tape a piece of cardboard about 10cm inside the keg to reduce the amount of gas needed to purge. I understand that it may not be needed, but I do feel like it will oxidise over time on the back side. I am having trouble uploading my photo of my keg, but I need to butt weld a circle in (there will be penetration regardless because of the gap), otherwise I'll have to cut my sides off to weld a 250mm ferrule in - there's also the added cost of a large ferrule and end cap. Perhaps I should just locate another keg that is intact and in good condition for now and instead put a 4" ferrule on the side like a had originally planned.
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Re: Welding a plate on top of my keg

Postby scythe » Sat May 12, 2018 7:34 pm

If it were me my first option would be to source a different keg.
Its going to cost you over $50 to mess around and weld the plate in, your going to have issues with weld quality, specifically pin holing if your only a novice using a bunnings TIG unit.

Also as for taping some card board to the inside that just sounds like a pain in the butt, especially as you need to get it back out afterwards.
Just fill it with water till just below (10mm) your weld, perfect air tight seal and minimal volume.
Another problem with back purging welds is the amout of argon you end up using.
Typically a TIG will use 15-20L/hr, the backpurge needs to be roughly the same rate.
So straight away you have doubled your gas usage.
You have to make sure the argon is moving otherwise you may as well not have used it at all.
Last edited by scythe on Sat May 12, 2018 7:36 pm, edited 1 time in total.
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Re: Welding a plate on top of my keg

Postby StillDrinkn » Mon May 14, 2018 9:34 am

Thanks scythe. I'm seriously considering grabbing another keg. I do have a few options for getting one in good condition luckily.
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Re: Welding a plate on top of my keg

Postby A&O » Mon May 14, 2018 10:37 pm

You can always use the keg with the chopped top as a fermentation vessel :handgestures-thumbupleft:
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Re: Welding a plate on top of my keg

Postby bluc » Tue May 15, 2018 8:48 am

Or mash tun :handgestures-thumbupleft:
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Re: Welding a plate on top of my keg

Postby RC Al » Thu May 17, 2018 1:06 pm

Sorry for the late reply, havent had access to a computer and i hate searching on a phone - i usually end up with 20+ windows open
The product is called weld backing tape, turns out there are heaps of different products out there, some are for holding bits of hot pipe together, some are for sealing pipes for argon purging, the stuff of interest to us is constructed like a continuous sticky wound dressing
ceramic tape demo https://www.youtube.com/watch?v=97ufJ2uLg3U
fibreglass tape https://www.youtube.com/watch?v=a4NlNHltRsc

The ceramic stuff seals and spreads heat, whereas the fibreglass stuff is supposed to capture argon from the welder to purge with

at the end of this thread using the masking tape is suggested http://www.ferrarilife.com/forums/ferra ... nless.html
saw it elsewhere a few weeks ago too in a couple of places

A lot of references i found for masking tape was for gas sealing not as a backing - using a high heat tape would seen appropriate though, have seen plenty of references to how messy and hard it is to clean melted masking tape off, so another reason for something better i think. An aluminium backed tape or something from 3M is most often mentioned

The Truth is out there somewhere!
http://www.aquasolwelding.com/fiback
https://www.blackwoods.com.au/part/0306 ... -64mmx23mm
Last edited by RC Al on Thu May 17, 2018 1:08 pm, edited 1 time in total.
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Re: Welding a plate on top of my keg

Postby scythe » Fri May 18, 2018 5:55 pm

Those look like a really good idea for industry, probably not cheap enough for us.
Especially when 48L or whatever it takes is basically free (in the scheme of things).
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