Silicon Bronze Tig Troubles

[AllyBill]

I've only ever had contaminated gas once in the past hundred or so years but it was disastrous. I don't use 100% argon on steel. I use it on aluminium, stainless or pretty much anything else but on mild steel I prefer an argon / CO2 mix because it just seems better able to tolerate mild contamination if working on old metal and overheating when you hit a thin patch.
If I use silicon bronze it's usually a last resort to save something that ought to be replaced so I do it with a neutral flame, lots of flux and lots of heat to keep it flowing and it will sort out its own pin holes.

Will

[Dave Z.]

Interesting...Ive heard of bad gas already. Its a bottle of straight Argon. I thought you couldn't use CO2 mix for tig welding. I have a bottle of Argon CO2 here for my mig. Maybe try that? Thinking about this in my sleep...maybe I had a dirty weld with the steel filler. Not the rod but my "technique"? And that just carried thru to the SiB? Seems I'm chasing the leak also...as if its not even at the original weld joint but under and onto the patch plate. Well I have all day to ponder this at work...lol...hope to hear more ideas from you guys. Thanks much!

[Oldnek]

It is definitely Silicon Bronze you have and not Silver Solder.???
I have used the wrong stick before with not to good results.

[neilho]

I've had good luck sealing weld porosity with Loctite 290. (One of its intended uses.) Steel boatbuilders use a lot of it to seal welds before painting, for example.

The old instructions say heat the weld to 170 degF and apply, let cool and wait 24hrs, but for tanks I feel more comfortable brushing it on and applying vacuum or low pressure till seen on the other side, then heating to 170, etc.

New instructions here...
http://www.na.henkel-adhesives.com/a...dTab=technical

No mention of preheating to 170 deg.

The last tank I did was my galvanized preheat water tank- the difficult part of the job was cleaning the uncured 290 off the inside surface of the tank. That was 4 years ago, still working well at 40psi.

[neilb]

have you tried SiBr on any other sheet steel than the tank in question?

if so what results did you get

[John Buchtenkirch]

Whenever I get any porosity with tig welding I lightly grind / clean the weld and then go over it again with the tig but using several feet of .030 mig wire from my larger mig welder. I’m told that there are more cleaners or de-oxidizers or some such thing in mig wire but whatever it is, I don’t care, it works for well me…….. has saved me quite a few times . I agree with Marty, let’s get a photo or two posted, that guarantees more accurate answers to problems. ~ John Buchtenkirch

[Dave Z.]

Ive used the Loctite 290. Ive used it to seal an oil leak in the casting on my Harley engine case. It worked great. I did consider it on my fuel tanks also. I guess I'm trying for "perfection" tho. I plan to coat the inside with a sealant to protect it from rust and its designed to stop leaks...but again...I'm hoping to not rely on a coating. Yes...they are SiB rods. All just purchased new. I did some thinking and I'm going to make a practice "tank". I build drivelines and do machine work for a living. I plan to use a short piece of 3 1/2" diameter by .065 wall driveshaft tube and weld ends on it and weld in a bung to put some air pressure to it to test my welds. I figure I can cut and weld and add things to this piece for practice. And...test it with a few psi of pressure. Maybe Ill see where I'm going wrong. Everyone I tell this problem to is stumped. I ran it by our welder today at the shop I work in and hes clueless. Hes said especially seeing bubbles following the edge of a weld...pin holes yes but that's odd.

[Dave Z.]

Neil...I tried it on other steel but just running a bead on a flat piece of sheet. I didn't test it with air. I did that before I welded my tank. I felt confident that I could weld my tank but once it went sour I focused on finding a cure. I should try different steel doing a butt weld and test with air. I plan to make a test piece out of a piece of tubing that I can practice on. As far as pics go...I'm a bit embarrassed to post what I have now with my gas tank...It looks like Stevie Wonder welded it with a rose bud tip on oxy acetylene...

[John Buchtenkirch]

Originally Posted by Dave Z.

As far as pics go...I'm a bit embarrassed to post what I have now with my gas tank...It looks like Stevie Wonder welded it with a rose bud tip on oxy acetylene...

When I read this I quickly lose interest in posting any further . Be a man and forget about your embarrassment......... don’t you think every one of us struggled a bit when we attempted a new type of welding. From your description of your poor welding it sounds like the more experienced welders in the group may be able to pick up on several mistakes you are making but not without some good photos . ~ John Buchtenkirch

[neilb]

I'm only thinking and may be way off but if the first weld with steel rod was porous then the second attempt with the SiBr may be porous but not as bad.

i will ask if the electrode in the tig was contaminated. also have you checked that gas is coming out continuously when you press the trigger and not just at the start?

its hard to diagnose a fault with a weld or welder when your not there.

don't worry about the tank if it looks bad, we all have crap we have done