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Metal corrosion question

I want to use some free pieces of granite to make water features. This will probably evolve or go down in flames, but I'm going to start with two types.

The first will be horizontal, using a large base piece of 3/4 granite, then successively smaller jagged pieces to form a rough pyramid. I want to use rod to support these, so that there is maximum see through space. Each "tower" would probably have no more than four square feet total pieces of granite to support. I want to tie them all together for strength and stiffness so that no "tower" is really free standing.

On the other, they will be mounted in a sheet fashion vertically, and the water will flow down the face. On those, I will have to bend hanger rods.

What would be the best metal rod to use? Stainless? Brass? Bronze? Marine stuff? I do have one of those shop benders that I have never used before, so should be able to get nice looking repeatable bends.

I don't mind it patinating, but don't want it to eat through. The water here is hard, and this will be using the local irrigation water because it's cheap, cheap, cheap.

Sources appreciated, but will try to buy local and save shipping. Might even get lucky and get some scrap. I can get stainless scrap, but it's all sheared flat goods. That would work, too, but then I'd have to get some TIG gear, which is a possibility. On edge and braced, that would be very strong, and visually attractive.

Steve

Reply to
SteveB
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"SteveB" wrote in news: snipped-for-privacy@news.infowest.com:

If, by "water feature", you're meaning "fountain" then you'll need to have a way to pump water to the top and, then, have it come back doen again.

A pyramidal structure consisting of multiple square/rectangular supporting SS plates held up by sections of rod/tube with a central tube through which the water would flow would be fairly straightforward.

Since, as you stated, you have access to a supply of scrap plate, all you'd need would be rod/tube to act as seperators and, for the water supply, the lift tube.

By using plate to support the stone - the stone's edges could, of course, be unsupported as long as you use enough SuperGlue to affix the stone to the plate - the support structure could be built far more easily _before_ having to dodge the stone.

[It would also let you experiment more easily by letting you do your prototyping with cardboard, plywood, or anything else that's cheap and handy and, during this phase, use styrofoam as a dummy "rock".]

One nice thing about using stainless: it's fairly simple to clean the CaCO3 off by simply soaking it down with 15% Vinegar, HCl, or whatever other mild acids are available.

BTW, had you considered using SS Allthread with nuts and washers to hold up SS plates upon which the stone would rest? These could easily be concealed by short sections of SS tubing.

That way, you could defer the purchase of that new TIG unit a little while longer...

Reply to
RAM³

Another option is to use weathering steel. CorTen is one type from USS. Other mills have roughly equal stuff. Plus there are generics. Figure a pretty significant corrosion rate and make your water feature metallic parts heavy enough to have a reasonable life. You'll notice the relatively new light towers on highway interchanges in the US are rusty looking. They're made from this stuff. No paint. Lasts a long time. Make sure you use reasonable estimates on the weight that the pieces are holding and keep the stresses low. In the 12-15ksi range I'd say. Less stress makes less corrosion. Stress and corrosion work together to accelerate decay. Plus the high safety factor minimizes your risk. If you can't run the numbers, get an engineer. If it's a public feature, you might find one who'll do it pro bono. I like the color of wet weathering steel. It's a deep, deep brown with great texture. You'll need to get special electrodes to match the colors if you need multipass welds, but they're available with a little effort.

I like the bronzes too. Silicon bronze, aluminum bronze and nickel aluminum bronze are available in plate sheet and bar. They're pretty metals and quite weldable but they're going to be a lot more expensive. Matching stick electrodes are available (I think - at least for some).

Using Stainless, you'll need to perform certain chemical or electro chemical post weld cleaning operations if you want them to remain stainless. Remember "Stain less is not stain free." Use the "L" grades if you can get them. Watch out for dissimilar metals at your anchors.

j
Reply to
John Gullotti

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