TIG stainless backing "flux"..?

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I have a weld set-up that makes it hard or impossible to use backing gas or solid backing for welding sanitary 316..My question to You is: Does it exist a type of paste/flux that can be used on the back-side of the weld? What about the penetration enhancing flux? What is it called/where can I buy it, and does it work as a backing in addition to increasing the weld penetration?Regards from NorwayBjornar
Reply:Its called Solar Flux type B. Mix it with alcohol and your good to gohttp://www.solarflux.com/Pages/Productinfo.html
Reply:Hey Bjornar,'Solar flux type b' can be used for protecting the backside of stainless welds. Not really suited for sanitary work though as it leaves a hard tenacious residue behind. Google will get you their web siteThe penetration enhancing flux,... i'm thinking you're referring to 'tip tig'. Never used it so no idea if it provides additional shielding but i doubt it. All i've heard about it (aside from the advertised increase in productivity) is third hand comments that it's nasty stuff you don't want to be breathingFor increased welding speeds and cleaner welds you could look at argon+ 2 - 5% hydrogen blends- won't add anything protection wise to the root thoughFluxcore TIG wire is another possability, TGX is a well known brand but again less than ideal for sanitary work
Reply:SolarFlux is garbage.  If you're welding anything more than drain pipe or something for chemicals or something that doesn't have to be that clean, it's ok...but nothing more.  In other words, if you could run a stick rod and tolerate the slag inside the pipe, then you could use Solar Flux.For sanitary work, you will not find any option that works like purging with Argon.  There's always a way to get argon into purge a weld.
Reply:Ignore 'tip tig' that was a brain fart, A-TIG is what i thinking about Originally Posted by EngloidFor sanitary work, you will not find any option that works like purging with Argon.  There's always a way to get argon into purge a weld.
Reply:brace yourselves - rookie question coming here.Why do you need to gas the back of a TIG weld on stainless? Is this solely an appearance thing or is it structural as well? Any pics out there to illustrate TIG welds with and without back-gassing ?
Reply:VERY basically stainless is, err, stainless because it contains more than 10% chromium. Chromium is pretty reactive and oxidises in air forming a chromium oxide layer a few atoms thick which is sufficient to protect the underlying material from corrosion. Provided a source of oxygen is available this film is self renewingAs you'd expect at higher temperatures the reaction is more vigorous, the colours you get on the metal when welded are due to a thickened oxide layer. Taken to extremes (not protecting the back of a weld) you get severe oxidation which looks like a pile of black crystals stuck to the back of the weld- known as a 'sugared' or 'coked' weld. This severe oxidation leaves the metal with less chromium available for corrosion resistance. How big of a deal is it,... depending on the application extremely to not very. Not too big of a deal for an exhaust pipe, more so for a manifold. I'd be more bothered about bits of the oxide being eaten by the turbo in the case of a manifold than corrosion thoughBottom line, it's easy to avoid by purging/flux or if the application is low stress by getting the weld parameters right so that the back of the weld doesn't get hot enough to oxidise heavilyThere's some pics of coked welds around here somewhere- try searching the site for 'stainless + sugar'
Reply:Originally Posted by EngloidSolarFlux is garbage.  If you're welding anything more than drain pipe or something for chemicals or something that doesn't have to be that clean, it's ok...but nothing more.  In other words, if you could run a stick rod and tolerate the slag inside the pipe, then you could use Solar Flux.For sanitary work, you will not find any option that works like purging with Argon.  There's always a way to get argon into purge a weld.
Reply:Originally Posted by hotrodderBottom line, it's easy to avoid by purging/flux or if the application is low stress by getting the weld parameters right so that the back of the weld doesn't get hot enough to oxidise heavily