Zinc Electroplating

What material will the tubing be, if not galvanized steel?

If you give more specifics on what, exactly, you are doing, it will yield better answers.

Electro-galvanizing, which is a variety of electroplating, is one choice. It looks about like aluminum. Hot dip galvanizing is usually the "thickest", with a characteristic "spangled" texture. Spray galvanizing is a third choice, with a grayish stippled look.

You might look under "metal finishers" for possible local services.

Why not weld up the assembly in steel, then apply a zinc rich paint? Instead of touch up painting?

Or get a quote from a local hot dip galvanizer to coat the final weldment? Check out http://www.galvanizeit.org/search/results/34b91d01fcc4f9e571b0d5755036994b/ for information.

BTW, I do not fault your welder for declining to work with welding galv material. The fumes are noxious and toxic. It can be done, but it is risky for anyone close to the action even with good ventilation.

You Say,

"Electroplate zinc varies in thickness depend on how long it's in the bath and you must specify what thickness you require. You cannot electroplate inside a tube."

If the tube is open on both ends so the bath can move through the tube, Why would it not plate the inside also?

Just curious as to why not?

Joe

the tube would be bout 5 feet long and 1/2 inch in diameter and like 18 ga wall

so getting an anode inside and yet not to touch anywhere would be next to impossible.

"...1/2 inch in diameter and like 18 ga wall" This sounds about like 1/2" thinwall wire pipe, or EMT. Is this what you are using?

After fabrication, will the inside of the tubes be exposed to atmosphere?

Do you wish to ensure this will never rust? If yes, why has steel tube been selected?

[edit] In review, you have not told us steel, but there is an implication steel is what we are discussing. What is the selected tube material?

yup EMT

EMT is available (in USA) as steel or aluminum...

I know you think you are telling us everything, but we don't have much to work with here.

What is the desired service duty and life? What is the consequence of corrosion or the price of a replacement fixture?

I think that is worth a GA.

Also it makes complete sense to me. The "distance" to the electrodes being different inside the tube to the outside.....

I am not up to speed with galvanizing in any way shape or form.....but find it interesting....

I gather a magnetic field forms inside the tube and stops the process. I believe a very thin coating forms, but its more colour than protection. Strange things happen at the ends of the tube too, its not an even coating.

Tony

I am no expert, but a few years ago I re-taught myself, after a 50 odd year gap, to weld, but using MIG/MAG this time. FANTASTIC!!!!.

My favourite material is Stainless Steel, I simply love working with it.

Consider making your object in SS and saving having any coating to apply or touch up or repair in the future.

It also looks good.

Which SS type you will need is a further question that we have enough experts here to assist you. I am only an amateur.

If properly cost checked, I would not be surprised if it is in the end, no more expensive to manufacture in SS, than in any other steel where rust/corrosion might be a concern.

I have no idea whether a version in brass, Bronze, copper, plastic, fiberglass or even aluminium might be even better, as you have not supplied constructional details. Even casting or similar might save money if large numbers are needed.

By the way, your welder is right, never weld on galvanize.....you need a special booth and filters to negate the poisonous gases produced.

Powder coating might also provide the resistance to corrosion, but I don't see that you have provided enough info into the final application to make a proper assessment. There are some powder coat systems that can be done in a consumer grade kitchen oven if you need only a few pieces and are experimenting.

If the main problem is the safety of the welder then proper safety devices can solve the issue. A certified breathing mask or SCBA ( Self Contained Breathing Apparatus ) will ensure safety of the welder as well as proper ventilation of all fumes is mandatory. I have welded on galvanized with proper PPE with no issues. There is available a zink rich coating to cover the welded area after cooling that works well. Industrial supply companies can advise.

Morning Roy,

I Googled for a

"A certified breathing mask" for when welding on galvanized metals. And had as usual hundreds of sites come back with suggestions. But i found a very common theme.

First I thought this was a "Vapor" problem. is it not? or is it actually a very fine particulate problem. Reason asking is, I at first was thinking of a face mask like a scuba gear, or like what firemen wear type of thing.

\

But 99% of the web page suggestions came back with a mask like this.

http://www.masksnmore.com/3m82n95paref.html

3M 8214 N95 Particulate Respirator w/Exhalation Valve and Face Seal

3M™ 8214 N95 Particulate Respirator w/Exhalation Valve and Face Seal recommended for welding on stainless steel, aluminum, galvanized steel, and other applications where low level ozone and nuisance organic vapors may be present. The 3M N95 Particulate Respirator 8214, N95, with Nuisance Level Welding Odor Relief provides a minimum filter efficiency of 95% against non-oil based particles. This product includes a faceseal with fully adjustable straps and a patented exhalation valve to provide comfortable and durable protection for extended periods of time. Available in one size only.

Is this truly real. That the welder wearing this would be safe to do welds on galvanized materials now? It then must be a particulate problem. for if it was a vapor problem this would protect nothing true?

Joe

While there are procedures that will allow the welding of galvanized metals, the bottom line here is that it will add to the total cost of production. The structural strength of EMT is minimal. Would a non corrosive material provide a better cost alternative? PVC, Styrene, Acrylic, all come to mind as alternatives that would not need corrosion protection, or expensive welding procedures.

Thanks everyone for all the thoughts here.

It gives me a LOT to think about and possible directions to go.

I'll be back in the future when I choose a path to take.

Joe

Forget plating and use a powder coated painted surface which is used by all the manufacturers of equipment that is used outside.

While I have to concur that equipment made of steel or iron used in and exposed to the weather will certainly rust, saying it only rusts on the inside has me baffled, just as Lyn has stated. I have seen what I term surface rust on the outside of metal, while an interior surface appears to be untouched. Sanding or grinding the outside, priming and painting or powder coating has been adequate for extended outdoor exposure, while no changes occur on the still untreated interior surfaces. I would like very much to understand your statement and ask if you would elaborate a little for the less educated among us, primarily and most certainly myself.

My point is that all it takes is moisture and air to make rust. Painting and powder coating the outside, protects the outside from exposure.

Without knowing more about the OP's requirements, it's hard to say how much rust is too much.

I don't blame your welder. Galvanized metal produces bad fumes. Most of the options have been covered quite well but just to round out this Zinc coating discussion with a few more options have a look at this process called Sheradizing. It uses Zinc vapour to coat the metal.

http://en.wikipedia.org/wiki/Sheradizing

This is the high end version that may lend itself to internal coating of tubes. The old fashion version as practiced in the late 1800s was to etch the metal with acid, rinse it to neutralise. Then pass it to the team of 10 year olds who are equipped with a small hammers and a big tub of powdered Zinc. They would take a handful of Zinc powder, place it on the etched area and bang it on with the hammers.

Some years ago I saw a modern application of the same thing. It used glass beads as hammers and was done in a tumbler. The parts being treated were springs and screws. They had been tempered and hot dip galvanising would have been detrimental.

Maybe the starting point is wrong and it needs to be made from something else. At this time, the forum does not know the temperatures and pressures and the nature of the fluids with which these assemblies will be wetted, nor anything about the structural strength required of them.

So why metal? How about ceramic instead? Carbon block? Glass? Plastics various?