"Welding" Unknown Pot Metal

On 2/8/2019 3:58 AM, Richard Smith wrote:
>
>> >>> Hi Gunner >>> >>> The "best" I met of welding on heavy hot-dip zink galv. which was
>>> infeasible to remove was welding in new deck-supporting truss >>> structure on a seaside holiday-town pier. >>> >>> Because it is >>> * a truss with slender members not blocking or setting up eddies in >>> the air >>> * there is a constant onshore breeze >>> this was the one-and-only occasion where you really could keep your >>> head out of the zink-fume plume and it was OK. >>> >>> Welding transversely across the truss members, you could look at the >>> weld end-on and manipulate the rod to puddle-up a correct-shaped >>> fillet despite the galv. kicking the arc around and the fume kicking >>> the weld-pool around. >>> And the arc was very lilac coloured indeed...! >>> >>> Best wishes, >>> Rich S >>> >> >> How did you rust-proof your welds? > > Galv.-spray. Zink-rich paint. Only thing you can really do (?) > Rich S >
What, you didn't build a vacuum chamber around each weld area and use vapor deposition? Shame. LOL.
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After welding some rust holes on the bed fenders of my truck I brushed cold galvanizing paint on sandblasted inner areas around the repair, with disappointing results. Although it didn't flake off, rust pinpoints appeared after a few years and slowly spread. New England roads are salted to melt ice.
The wheel wells were much easier to work on with the bed inverted and raised on blocks.
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In UK, where mildish winters but a lot of salting with temperatures around zero C, galv.-spray over grit-blasted lasts only a couple of years or so. Maybe three of four - nice. But it's quick to blast back and respray. Do it as the summer goes on (warm and dry), mindful your vehicle will look after you as we tip into the long cold darkness.
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On Fri, 08 Feb 2019 14:11:14 -0700, Bob La Londe wrote:

Actually zinc is routinely flame sprayed in open air. (Vapor deposition is too slow for anything but very thin coatings anyhow.)
https://acblastingservices.com/zinc-hot-flame-spray/
First hit I found, a bit more searching should turn up details. The equipment is expensive, but entire bridges have been coated with this method in corrosive coastal areas where paint has a short lifetime.
Not really practical for the home or small shop unfortunately.
Glen
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On Sunday, February 10, 2019 at 6:01:51 PM UTC-5, glen walpert wrote:

One company that makes zinc spray equipment is in _Silverdale Washington . They use two miller power supply and feed two zinc wires so the arc is be tween the two wires and use inert gas to blow the molten zinc to the bit t hat is being coated. At least that is what I was told. I would like to try using just one wire in a MIG welder. But have not really looked for th e wire. I expect the use of two wires reduces wire sticking and jamming.
Dan
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