Brass vs steel

[KarlKobel]

I made my tender tank with 316 stainless steel
I was fortunate enough to obtain sheets of 4x7 0.07 sheets.
It was a challenge to make it possible to transport them from Texas to Illinois in my sub-compact, but that's another story.

The choice of 316 SS made it difficult to work with, but the price was right.

Rather than post pictures in this thread, visit http://www.karlkobel.com/Tender/TenderTank/index.html if you are interested.


Also consider that stainless steel is only stainless due to the oxide layer. If that layer is removed, for example during soldering, it must be restored by a process called passivization. I learned that the hard way for one of my turret valve stems. The worst thing you can do to SS is use a wire wheel (it removes the oxide layer and embeds ferrous material in the pores). There may be industrial chemicals to do this process, but I used oxalic acid powder (Barkeepers Friend also contains this compound).

Karl

[michaellynn2]

My tender is all brass and I built an auxiliary water car out of brass.

[Steve Goodbody]

Some great ideas and good points here.

To throw another option into the mix, for my saddle tank I went down the route of using a copper inner tank surrounded by a dummy steel tank. While extra work, I did this for a few reasons which may or may not be applicable to others:

1. It allowed me to fully insulate the inner tank to keep the water cool for injectors.
2. It avoided having to worrying about rust-proofing the water tank.
3. For me, it was more forgiving and the end result was ultimately neater. On the inner tank I could concentrate on getting everything soldered water-tight without worrying too much about appearance, and on the outer tank I could concentrate on appearance without worrying about leaks.

Best regards
Steve

[rkcarguy]

I'm with Steve (above). Also, companies like plastic mart offer a huge selection of sizes and shapes of various tanks for boats and RV's, so fitting a nice polymer tank into a steel shell is also an option.

[gwrdriver]

To throw another option into the mix, for my saddle tank I went down the route of using a copper inner tank surrounded by a dummy steel tank.

Steve,
For tanks I might build a copper liner is impractical, but for general information, what size was your saddle tank and what gauge copper did you use?

[Steve Goodbody]

Hi Harry,

If I remember correctly, I made the main wrapper of the tank from 14 gauge copper and the end plates from 16 or 18 gauge brass (I don't recall which). There are also two inner baffles, made I think from 18 gauge brass. The tank holds about 3 gallons and is roughly 16 inches long, 12 inches wide, and about 3 inches wide around the boiler.

This raises a downside of copper/brass tanks in today's world - those materials would be very expensive if bought today.

Best regards
Steve

[gwrdriver]

Thanks Steve. A 16x12x3 isn't all that big, I had envisioned larger, still . . . small enough to make it fiddly in places.
Did you use anything to isolate the Cu metals from the steel to avoid galvanic corrosion?

[Steve Goodbody]

Hi Harry,

In answer to your question, one of the advantages of the dummy exterior is that the whole outer tank (including all of the faces that form the mounts for the inner tank) can be thoroughly painted before assembly. Hence paint provides most of the galvanic isolation between the dissimilar metals.

However, the front of the outer saddle tank is mounted directly to the smokebox by two brackets which obviously get hot. At this location, to avoid conducting that heat to the inner tank, I installed a gasket between the inner and outer tank mounts. This gasket provides additional galvanic isolation, but that wasn't my primary aim.

Best regards
Steve