(I posted this to RCM -- 'didn't think to post it here, where it would do more good)
The question of how to remove the oxide discoloration resulting from welding stainless comes up from time to time. Praxair has a new solution, said to be safe.
I don't know anything about it but there is a brief mention in our new magazine, _Welding Productivity_.
formatting link
You're seeing that issue before the rest of the world will see it. It probably will go live tomorrow. It's still undergoing some editing.
Anyway, if you're interested, call Praxair.
BTW, if you like the magazine, you can subscribe for free. The website isn't quite ready for you, but the subscription form should be up in a week or two.
I was using citric acid and 24 volts DC to passivate and clean stainless welds 20 years ago. It is not a new process. I liked it because I had to do work in breweries and kitchens. Very safe and non-toxic.
The stuff I used is called Citrisurf, by Stellar Solutions.
Yes, there have been electrolytic solutions for decades. What's different about this is that it's just a brush-on, with no electrical involvement.
It appears to be a straight replacement for hydrofluoric acid. They say it contains "no free hydrofluoric acid." Maybe it's unfree.
Again, I know nothing else about this stuff. If anyone is interested and can't get straight info from Praxair, let me know. They're a partner on one of our publications.
Tried looking up this weld cleaner on the Praxiar site, got 135 hits. Slow internet down here, so wondering if you know the exact name of this safe weld cleaner.
Being an abattoir, most of our welding is 304, and welds must be cleaned. We use a nitric acid solution with an electric wand, sold by Wurth, and a gel from someone else that is an acid.
Want to see if I can interest our welding supplier in trying to source the Praxier or Citrisurf stuff. On the safety committee at work so part of my job now is to look for safer alternatives.
Fast Acting, environmentally friendly solution that better protects workers
improves and makes the removal of chromium oxide and heat tint from stainless steel safer. The new, 3-in-1 exclusive formula contains no hydrofluoric acid. It is available in a paste which can be applied by brush or sprayed on and a gel for dipping complex fabrications without the need for extensive PPE or the risks of hydrofluoric acid burns. When ready, it can be water-rinsed or wiped off with a damp cloth.
ProStar Stainless Steel Heat Tint Remover is water-soluble and employs "smart technology" that only attacks the oxides which cause the weld heat tint and reduction in corrosion resistance. And, when the oxides are gone, it turns off, protecting your fabrication - it can be left on indefinitely.
"The metal fabrication and welding industry has long-awaited this solution," said Chris Vihnanek, Director of Metfab Productivity at Praxair. "The ProStar line of worker- and environmentally- friendly products will save our customers a lot of time, allowing them to focus efforts on other ways to improve productivity and boost their bottom lines."
Praxair's ProStar line also features the De-RUST rust remover and DE-BOND paint and coating remover products which also employ "smart" technology which targets the problem areas, protecting the substrate.
Ok, I talked to our contact at Praxair, and this stuff is even better than they let on in the press release. It won't attack the stainless at all, only the various oxides, so the heavy-metal problem is vastly reduced. It's safe enough that you can brush it, spray it, or dip it (different versions of the material). If you rinse off hydrofluoric acid or the acid you're using with an electrolytic process, and let it settle in a tank, the draining frequency for hazmat purposes, by comparison, is only something like 1/4 as much.
I didn't talk to a guy who's involved in shipping, but they gave me a name and number for you to call. You want to talk to Mark Clemente at
1-262-938-6300. If calling is a problem for you from Australia, let me know.
Good luck with it, Jon. The guy I talked to is Larry Cherne, by the way.
It is available, Bill, and they have some big customers using it. I talked yesterday with one of the Praxair managers and he sounded annoyed that the website isn't up to speed with it.
You might have to call Praxair at 262-938-6300 and ask for Mark Clemente. If he's not available and you need to try for someone else, use the product name that's at the top of the press release I posted for Jon.
They'll catch up with their promotions. Praxair has a lot of products.
Did you get any idea of the cost? A look at the MSDS would give you an idea of what it is.
Instead of using something to remove the oxides, one could use Solar Flux or Superior Flux No 9 to shield the metal from oxygen.
I am always interested in new products, but I do not see any stainless welding coming up in the near future, so I will not be bothering the Praxair reps until I see a need for it.
No, I didn't ask. I sent an email to them after talking to Larry Cherne, thinking I might write a short item about it, but I haven't heard back yet.
I think that most applications involve the three biggest TIG-welding stainless applications in industry: food-processing equipment (especially dairy); pharmaceutical processing; and industrial chemical processing. All three involve a lot of tanks and fittings. All three also are very specific about what methods are allowed. I don't know what fluxes are allowed.
It may just be a little bit too early. They've been selling it to some customers, but I was just going on a press release, except for what I got from Larry. They may not be actively marketing it yet.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.