Vintage boilers: metal(s) ?

[timo888]

After descaling, the inside of my 1970s era Oly Club boiler is the color of Georgia red clay, while the outside is a silverish yellow. Are there two different brass alloys here? Is this a yellow brass boiler lined with red brass?

Regards
Timo

['Q']

Although I'm no expert, I doubt they fused two alloys when building the tank. Instead I would guess that leaching either from the metal to the water or water to the metal has caused the internal surface of the boiler to change color.

[mogogear]

The color says Copper........? Perhaps?

[timo888]

Although I'm no expert, I doubt they fused two alloys when building the tank. Instead I would guess that leaching either from the metal to the water or water to the metal has caused the internal surface of the boiler to change color.

My neighbor, who is pretty experienced with metals, agrees with you. He says the zinc has probably leached out over the years. See selective leaching.

Regards
Timo

[timo888]

The color says Copper........? Perhaps?

I was hoping the interior was copper plated, but I gather not. Haven't heard back from the company that does FDA nickel plating.

Regards
Timo

[espressme]

I was hoping the interior was copper plated, but I gather not. Haven't heard back from the company that does FDA nickel plating.

Regards
Timo

Hi Tim,
What has happened is that you have "pickled" the surface with the cleaner. That removes all the elements other than copper from the surface. During smithing of copper, bronze, and brass; that is the usual effect after annealing when the fire scale is removed by acid etching. But, that is not the only process which does that.
That pure copper surface is only a few molecules thick.
richard

[mogogear]

Good news Tim- Plating is usually only a few molecules thick- you now have a copper plated boiler -! a patina will form quickly and all will be fine

[timo888]

I am considering gold plate on top of a nickel substrate

[timo888]

What has happened is that you have "pickled" the surface with the cleaner. That removes all the elements other than copper from the surface. During smithing of copper, bronze, and brass; that is the usual effect after annealing when the fire scale is removed by acid etching. But, that is not the only process which does that.
That pure copper surface is only a few molecules thick.

What is that whitish-gray powdery coating that keeps appearing?

Regards
Timo

[espressme]

What is that whitish-gray powdery coating that keeps appearing?

Regards
Timo

Hi Tim,
IIRC
Most often, I would believe, that residue would be a tin/zinc oxide ( depends upon the material spec.) And it takes a couple of applications of scrubbing wih Cafix®, Cafiza® or a similar ( Trisodium phosphate,) no foam, custom coffee cleaner to stop the process.

Chemically, the "base" ( alkali ) of the cleaner neutralizes the acidic metallic / acid compound residue from the use of the pickle/acid cleaner. In a washing machine you do the opposite and add a mild acid (white vinegar works)to remove/neitralize the alkali of the detergent during the second rinse cycle. Cheaper than fabric softener.

Hope that helps!
sincerely
richard
PS. Other opinions requested!

PPS What is now sold as TSP® is not! They ( present conglomerate ) copyrighted the chemical name and substituted a detergent. If you read the box, It says "No Phosphates!" Some paint stores have the real thing.

[timo888]

Since I had no Cafiza on hand, I swabbed the interior of the boiler down with a baking soda solution. Two applications appear to have stopped the oxidation.

Thanks for the explanation, Richard.

Regards
Timo

[timo888]

Now, if the nickel plating on the interior of the boiler is active (i.e. not passivated), and the heating element is copper, and there is no sacrificial anode, then, according to this Chart of the Galvanic Series, it is only a matter of time before the nickel plating inevitably corrodes because copper is nobler than active nickel.

Can nickel plating on the interior of the boiler be passivated (in a food-safe manner) so that it is nobler than the copper element? Or, are sacrificial anodes available pre-fab in a standard BSP or NPT thread appropriate for a 3liter boiler?

EDIT: The answer is yes. E.g. at McMaster:

3606K6
Zinc Corrosion-Inhibiting Rod 1/4" NPT, 3" Rod Length, 3/8" Rod Diameter
In stock at $5.88 Each


Now the question becomes, is this kind of zinc rod appropriate for a potable-water system?

Regards
Timo

[espressme]

Hi Tim,

Hi Richard,
The specific wear-issue I was trying to solve is the deformation of the slot in the fulcrum mount and the wearing thin or even the wearing-through of the brass at that location. The abrasion there is much exacerbated by the thousands of pounds of force applied to the hardened steel pin and then to the brass, via the lever. If Delrin is harder than brass (I think it is), it might make a decent slot liner. I don't know how thin it can get before it looses its strength. Perhaps something like this, but less ovoid and more lozenge-shaped:

Well Tim, brass by its nature does work harden and develops a very hard layer on the surface and to a depth determined by the force ( No, I cant give you a formula! )
Delrin is a good bearing material for a radial bearings or rotational bushing but can be pressure cut. ie. A cut made by displacing the material by extreme unit are pressure. Thats what a knife does. Applies the greatest pressure to the smallest area.
The deformation of the slot is mostly just plain pressure bending of the material, by and after wear has reduced the thickness of the parent material.. Unless a stainless steel insert were placed above the slot there is no way that abuse will not deform it. I can not think of a fastening system to accomplish such a feat. But, that said, I would suppose a hardened 440 series Stainless steel bar could be inserted and J-B wWelded in place in the top of the slot.
I would believe that the lubrication of the pin roller tube would be of immense value. That changes the force from a pressure friction to a rolling pressure and would reduce the scraping of the top of the slot. But, within the slot and supported by the parent material.

Teflon-coating of the piston cylinder is something I would consider; you know the EPA's take on brass in potable water systems.... Wink I have been reading about electroless nickel-teflon coatings, but will look for Magnaplate.

BTW, the company that originally said it would take on the job of replating my boiler has gone incommunicado. Can you recommend another who might have experience with Magnaplate?

Regards
Timo

The materials are applied by select electro-platers around the country.
This is Magnaplate' url
http://www.magnaplate.com/
andhttp://www.magnaplate.com/solutions/certification.html
enjoy!
richard

[timo888]

Teflon-coating of the piston cylinder is something I would consider; you know the EPA's take on brass in potable water systems.... Wink I have been reading about electroless nickel-teflon coatings, but will look for Magnaplate.

BTW, the company that originally said it would take on the job of replating my boiler has gone incommunicado. Can you recommend another who might have experience with Magnaplate?

The materials are applied by select electro-platers around the country.
This is Magnaplate' url
http://www.magnaplate.com/
andhttp://www.magnaplate.com/solutions/certification.html

Thanks for the certification link.