Cold Zinc Galvanizing

[dstig1]

I need to make a couple of post bases, as the posts are not a standard size for typical hardware. It looks like the best method (with what I have on hand...) is to weld them up from plain old bar stock. These will get buried in concrete next year, so they need more than a rattle can of primer and black. I was thinking about using one of those cold galvanizing "paints" to get them protected, and then possibly painting. I have done some web searching and found some options. The one from ZRC looks pretty solid, but everyone has their claims of Super Awesomeness (tm) so who knows? Thinking of cold zinc then primer and some topcoat, but I see the zinc guys say "no alkyd containing paint to topcoat" which covers just about everything out there in rattle can land. I'm looking for tips, suggestions, experience, etc. Posts are 8 3/4" square. Open to other additional suggestions, but the posts are already on site, so I am not getting smaller or larger ones...

Thanks Welding crew,
Dave

 

[yomax4]

I've used cold galv. for primer many times and put rustoleum paint over it. Never had an issue. Lots of brands out there. I've used CRC, Rustoleum,Arc Air and Welco. All seem the same but may have different properties. I've even welded through it with fair results.

 

[dstig1]

Thanks. I ordered a can of the WRC stuff as nobody had anything locally. I was a bit surprised by that... I'm sure it will work fine. I may have to coat some parts before final weld as they will be inaccessible after I put the last couple plates on, so it will be time for the respirator for sure (heck, I almost always wear a respirator when welding anyways...)

 

[Gary Fowler]

ZRC brand is 98% zinc and is what we always used to do field repairs to galvanized parts after welding. It works really well. We (industrial construction folks) never paint galvanized so I cant speak to how well paint would adhere but I would think it would hold better on the ZRC than on the galvanized. It takes an acid etching on galvanized to make paint stay on which is one reason we never painted it. Galvanized doesn't need additional paint for protection.

 

[Texasmark]

I have used whatever is sold locally in the rattle cans; don't remember brands. Put on an ample supply. Worked for me.

Mark

 

[yomax4]

Also if you bury in concrete, There may not be any air in there and the posts wouldn't rust anyway. Only where they stick out.

 

[LD1]

It would cost more but for piece of mind, you could fab up the bases with stainless. Perhaps dig through a stainless scrap pile at your local supply to get it a bit cheaper?

 

[Reverser]

Also if you bury in concrete, There may not be any air in there and the posts wouldn't rust anyway. Only where they stick out.

That's what I was thinking. In all the pipe I've seen buried in concrete that have rusted through, the weak spot has always been where the post meets the concrete at the top of the ground. But still the post will last for many years before it rusts through. Many times it will be an old sign post that long outlasts the business they were advertising.

 

[Reverser]

It takes an acid etching on galvanized to make paint stay on which is one reason we never painted it. .

Many years ago, I skirted a building with galvanized roofing. I was thinking about painting it to match the building and was told that an old time way was to coat the galvanize with vinegar, then paint after it dried.

I put vinegar in a pump up sprayer and wet it down, and later painted it with the same latex house paint I used on the building. I expected it to flake off, but it never did. It was still on there when I sold the place 10 years later. I suppose the acid in the vinegar etched the galvanize well enough to paint.

 

[CNC Dan]

Also if you bury in concrete, There may not be any air in there and the posts wouldn't rust anyway. Only where they stick out.

Not just lack of air(O2), but the alkalinity of the concrete tends to passivate the steel.

 

[Soundguy]

could hit it with asphalt based paint if really worried...

 

[Reverser]

Soundguys post made me think of a storm shelter I bought one time, made out of sheet metal. The guy that built them said he usually encased them in concrete, but said I could save $1000 by coating it with asphalt roofing tar (mastic?), and then buried.
Since I was watching pennies at that time, I went that way.

He delivered the shelter and I coated it with several gallons of roofing asphalt. He came with his backhoe a couple weeks later and buried it.
As far as I know it's still OK after about 30 years.

 

[Soundguy]

we put in culvert pipe. it's galvanized pipe, and in some cases, it's asphalt coat galv pipe. ACCMP is what we call it.... ( asphalt coated corrugated metal pipe )

 

[dragoneggs]

could hit it with asphalt based paint if really worried...

Yep solid advice in my book. Clean it up with some vinegar first and it should last longer than you.

 

[dstig1]

Thanks guys. Not sure if the asphalt paint would work as this galvanizing stuff has some organic binder in it. Has to, to be paintable. That seems to be why they tell you not to coat with an alkyd paint. I'm going to just goop it up good with the zinc and call it good. The stuff above grade might get some paint at some point, but probably not as it is going to all be covered with decorative stone work down the road.

I got the bases cut and welded up today, mostly. Still need to weld on the faces to tie it all together (like it is going anywhere... ) but I need to zinc coat it first as I won't be able to access the inside easily after that. 1/4" flat bar stock, except the 2 flat horiz plates that are 3/8" (mis-communication from the supplier - was supposed to be 1/4 also, but thicker won't hurt.) And I thought 1/4" was overkill ....

 

[dragoneggs]

Thanks guys. Not sure if the asphalt paint would work as this galvanizing stuff has some organic binder in it. Has to, to be paintable. That seems to be why they tell you not to coat with an alkyd paint. I'm going to just goop it up good with the zinc and call it good. The stuff above grade might get some paint at some point, but probably not as it is going to all be covered with decorative stone work down the road.

I got the bases cut and welded up today, mostly. Still need to weld on the faces to tie it all together (like it is going anywhere... ) but I need to zinc coat it first as I won't be able to access the inside easily after that. 1/4" flat bar stock, except the 2 flat horiz plates that are 3/8" (mis-communication from the supplier - was supposed to be 1/4 also, but thicker won't hurt.) And I thought 1/4" was overkill ....

Looking good!

 

[Soundguy]

I doubt there would be any problem, when we cut ant join pipe with band couplers, the sawed or torch cut ends get painted with a grey zinc rich paint as well, the it gets the asphalt recoat, if it was accmp. In our case we do the asphalt for county specs, etc.

I think you will be fine either way, good luck.

 

[Reverser]

Looking good!

Agreed! +1
It'll probably still be standing when the pyramids crumble.

 

[Reverser]

I doubt there would be any problem, when we cut ant join pipe with band couplers, the sawed or torch cut ends get painted with a grey zinc rich paint as well, the it gets the asphalt recoat, if it was accmp. In our case we do the asphalt for county specs, etc.

I think you will be fine either way, good luck.

Soundguy, by band couplers, are you talking about using the type that have a compression ring, like Dresser fittings/couplers?
We used to use them out in the field in emergencies when we couldn't repair the threads, or had to torch cut the ends of the pipe.

 

[firemanmike69]

What about having them hot dipped?