PDA

View Full Version : Home Shop Hot Dipped Galvanizing



JoeLee
04-05-2016, 10:58 AM
Any one ever tried it before???

I have six small rods that I need hot dipped. Every place I've called has any where from a $200 to $400 minimum and they are all out of state. Just not feasible.

There isn't much to the process other than a sulfuric acid bath to remove mill scale and other contaminates.

Not sure if there is any flux bath required and then the zinc bath at about 850 degrees or so.

I could make a small tank or easier yet, get one of those long stainless food pans. Where do I get the zinc????

JL.................

adatesman
04-05-2016, 11:01 AM
Where do I get the zinc????

Got a penny jar? :)


(EDIT: Modern pennies are nothing more than a copper-clad zinc disk, and it's easy to separate the two... put a nick in the copper, apply heat, and the zinc runs out)

GEP
04-05-2016, 11:11 AM
Go to a marina they sell pure zinc that is used on boats to keep all-gee of the hulls also a roofing supply will sell pure zinc strips, you also need some washing soda the rest you will find in you kitchen
https://www.youtube.com/watch?v=Wy6u2kikAA4

JoeLee
04-05-2016, 01:06 PM
The youtube video is the electro plate process. I'm talking hot dipped.
Good thought on the marina and the zinc anodes.

JL................

RWO
04-05-2016, 01:22 PM
Just flux them up with plumber's acid flux and tin them well with old style 50-50 lead tin solder. You then have a very corrosion resistant coating similar to what use to be used to make auto gas tanks, sheet metal roofing, etc., so called Terne metal. Real Terne is actually 10-20% tin and the rest lead. However, I coated some gas tank brackets with 50-50 solder for my old PU and they lasted at least 20 years with no apparent corrosion when I sold it.

RWO

Baz
04-05-2016, 01:35 PM
There is also a technique where you feed a zinc wire into a small but air blown gas flame. The force of the air is sufficient to blast small droplets of zinc as it melts to hit the target. Gosh, it still exists (http://www.plattbros.com/zincwire.php)and not banned by HSE.

JoeLee
04-05-2016, 01:39 PM
I talked to a guy at a galvanizing supply place. He was real helpful. The pickling or acid wash can be done with muriatic acid followed by a cold water rinse
and then the flux bath. They use some salt type flux that is diluted with water. I didn't ask him if soldering flux would work. Pure zinc is what is used.
Boat out drive anodes will work ok I can by the zinc ingots. The stuff is cheap. A steel tank and a propane burner is all that is needed. The zinc starts to melt at 800 deg. and 850 is the preferred temp.
This is my next project when the weather warms up.

JL...............

GEP
04-05-2016, 01:55 PM
The youtube video is the electro plate process. I'm talking hot dipped.
Good thought on the marina and the zinc anodes.

JL................

I had some parts i make for old tractors that needed to be coded for rust more substantial then paint the cheapest and effective way to protect steel was the zinc plating processes. Hot dipping is a more drawn out processes that i did not want to deal with at that time but maybe in the future let me know of the way to do it you come up with

cameron
04-05-2016, 02:12 PM
I've used sal ammoniac as a flux. Too long ago to trust my memory, but I seem to recall the salt was floated on the molten zinc so that the part passed through it .

wierdscience
04-05-2016, 02:15 PM
Aladdin galvanizing bar-

http://www.xpress-test.com/catalog3.htm

I've used it to repair Galv surfaces and do small items,it works good,contains all fluxes etc.Just do it outdoors with a fan blowing the fumes away.

old mart
04-05-2016, 04:11 PM
Be sure to bone up on the hazards of molten zinc before starting.

boslab
04-05-2016, 04:33 PM
+1 to molten Zn. Watch out for closed chambers, vent them
Mark

Rosco-P
04-05-2016, 04:47 PM
Be sure to bone up on the hazards of molten zinc before starting.



Wouldn't a yellow zinc (zinc chromate) plating offer sufficient protection for four rods? What kind of environments will they be exposed to?

JoeLee
04-05-2016, 04:48 PM
Be sure to bone up on the hazards of molten zinc before starting.I'm going to be doing this out side so ventilation isn't going to be an issue.

JL................

firbikrhd1
04-05-2016, 07:30 PM
I'm a hot dipped galvanize fan myself but more and more I am seeing epoxy coatings in place of hot dipped. What's driving it? Expense, EPA regs, other?
I think If I were going to do a home corrosion resistance job I'd be looking into epoxy coatings myself for bother safety and ease of application reasons, after doing a lot more research of course. Apparently the coatings I'm referring to are pretty good though, I see them used on rebar for applications near salt water.

Stepside
04-05-2016, 07:45 PM
I had some welded gates galvanized. Because they were welded tubes, every tube had to have a vent hole. they wanted a 1/4 inch diameter hole. The preferred placement of the hole was so the whole thing could drain while hanging vertically.

boslab
04-05-2016, 07:52 PM
I'm going to be doing this out side so ventilation isn't going to be an issue.

JL................
I guarantee you outside won't make a bit of difference, if you smoke you will find cigarettes will start to taste really funny, shiver shake and ****e will follow closely, oh and a hangover without drinking.
Respiratory protection is a must with Zn, there are filters for it.
Try cutting some galv steel with a torch, you soon find out!, zinc sublimes, the vapour gets in quick, and doesn't like leaving.
Apart from that it's quite doable in small batches, it might be safer to electro galv but where's the fun in that.
Warm everything, thoroughly
Mark

JoeLee
04-05-2016, 09:54 PM
I know exactly what you mean about cutting or welding through zinc.

JL................

JoeLee
04-12-2016, 09:54 AM
Does anyone know what one cu. ft. of zinc weighs. I pulled up some info and I get about 435 Lbs. If this is true even with a small tank of about 4" wide x 4" deep x 13" long what would that weigh?? and what would it cost me to fill it?? What this project is looking like is not feasible for me to do.

I've called all the local scrap yards and they don't bother with the stuff or separate it.

The other issue I've been thinking about is will I be able to get a tank that size hot enough with propane to melt the stuff??

JL..............

lbender
04-12-2016, 10:18 AM
Pure zinc weight 440 pounds per cubic foot.

metalmagpie
04-12-2016, 01:41 PM
I have prepared dozens of weldments for hot-dip. Pay attention to the advice to vent ALL closed areas. If you had a square tube that was welded shut at both ends, but there was a tiny pinhole in one weld, then liquid can come in during the pickling bath or rinse steps. Then if you submerge the thing into zinc at what, 800 degrees or something, that liquid flashes to steam and then you get a bomb. Which could blow melted zinc all over you. Which could kill you.

My galv guys require 3/8" holes at the tops and bottoms of blind holes. Then they lower the part so the tube parts go in vertically and the inside can fill with zinc. Also, when you lift it out, then the excess zinc can drain back out. And your tubes get galvanized on the inside as well as the outside.

There are several preliminary steps to hot dip galvanizing. It usually starts with a hot caustic soak which removes all traces of paint and grease. That is followed by a pickling (acid) soak which removes any rust, leaving the part chemically clean. This is followed by a hot water rinse. Only then does the part go into the molten zinc.

Also be aware that doing this at home is almost certainly illegal. No new galvanizing businesses are or ever will be built again. The old ones are grandfathered in but they are almost constantly inspected. Disposal of the various chemicals is a big issue. If a neighbor snitched on you and you get caught you could be in serious trouble.

The galvanizing shops in Seattle have a $75 minimum. If I were you I'd ship your parts to a commercial business and be done with it. They will be competently processed and shipped back to you.

As for epoxy instead, I am skeptical. I believe it may be effective to apply an epoxy coating over a hot-dip coat, but don't forget the maxim that rust always wins. The very best solution is a top quality paint over a hot-dip base. That will last for many years, and the paint can be renewed as needed.

metalmagpie

oddball racing
04-12-2016, 03:16 PM
Boat anodes are no longer pure Zinc. Been there done that.
I Was told that the " new alloy" works better and is not as sacrificial. Bought one to try anyway and it turned my electrolyte into a murky mess.