Shavarsh Reader
9/13/21 7:24 p.m.

Hello All,

I am trying to make a filler plate for my fuel cell and trying to tig weld stainless without a back purge is giving me fits. I've got some solar flux here and it works fairly well, however I don't want the residue falling into the fuel at some point and clogging the filter/carb. The bottle on the tig I have access to is only a single regulator. What are your cheap/simple back-purge setups? Lets see em

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
9/13/21 8:31 p.m.

I have a T and a second regulator.  When I don't back purge, I just turn the second reg down to zero flow. I use tinfoil for plugging tubing, or creating a "dam" around the backside of an object.

I've used lots of Solar Flux.  Any reason why you can't clean the residue off before putting it into service?

Shavarsh Reader
9/13/21 9:57 p.m.

In reply to SkinnyG (Forum Supporter) :

Thanks Skinny, here is the part I'm currently working on. I'm thinking that the access to the inside of the part will prevent me from effectively grinding it off.

I'd like to get away without a second regulator. Could a T, and a constriction in the second line, work well enough to get this part done? 

malibuguy GRM+ Memberand HalfDork
9/13/21 10:05 p.m.

I use this.  Had it for 5 years with no problems.

I do exhaust and turbo fab.  In the early days I ran the purge hose thru a finger of a latex glove and tape or foil off the other side with a few pin holes to allow for purge thru.

Now days I have purge plugs for my more common sizes and use the glove for oddball stuff.

Shavarsh Reader
9/14/21 2:21 p.m.

Alright, my bad, I should have googled first. Here is what I was looking for. Hopefully someone else finds it useful as well:

malibuguy GRM+ Memberand HalfDork
9/14/21 6:33 p.m.

edited mine...I didnt realize it didnt post the link for whatever reason


TVR Scott
TVR Scott GRM+ Memberand SuperDork
9/15/21 8:42 a.m.

I've been down this road.

Simplest way is just foil tape and a hose stuffed in the end:

You'll have to clean off tape residue, but it comes right off with acetone.

Another bargain tip: nitrogen works great as a back-purge gas for stainless!  And it's way cheaper than argon.

I have built some specific purge plugs too, but the tape works pretty well.

For your parts, the Solar Flux would maybe be a good way to go.

stafford1500 GRM+ Memberand Dork
9/15/21 9:50 a.m.

The Solar Flux that can be brushed off is easy to remove. The stuff that gets hot and melts is next to impossible to remove, so I would not bother trying to gring it out. Leave it alone and carry on, it will never fall off on its own.

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