Large Scale Central

Galvanic corrosion of Stainless Steel track?

I noticed this during the winter, but didn’t connect the dots until yesterday. The stainless steel rails through my concrete Walk Crossing have rusted over the winter. These rails have been embedded in concrete for over 5 years with no ill effects until recently. What changed? Since late last summer 12V @ 5A power charges the rails for a lighting buss 12 or more hours a day. Only one polarity rail is rusting…

Had I realized this would happen I could have shut the power off to this section as it is still controlled by block switches. I actually attempted to get this look once with the steel wool and vinegar solution, but it bleached away quickly in the sun. I guess I just have to swap polarity for the next six months to even it out

The track condition is not an issue as I am 100% battery or live steam power for locos but I might try and polish the rail tops for appearance sake.

I had something similar with DCC, but both rails because it is AC… I used to leave the power on 24/7… all the connections underneath my Aristo switches dissolved. I did just pull up a piece of track that apparently was moist all the time and the web had rusted/corroded/eaten away. (I’m all stainless Aristo)

Greg

Regarding the Steel Wool and Vinegar: it doesn’t bleach.

Being stainless, only ‘rust dust’ sticking to the rail is what you see. I found I had to mist a clear Acrylic Clear Coat to keep it robust. Some clear coats blew the rust away, so I found one with a misting tip and let it drift down for the 1st coat.

Run trains to polish the rail! Darn took longer than I thought… win win.

John Caughey said:

Regarding the Steel Wool and Vinegar: it doesn’t bleach.

I won’t argue, but it did “weather” away rather quickly - even where I stained the concrete. Same with ballast that I tried it on.

Greg Elmassian said:

I had something similar with DCC, but both rails because it is AC… I used to leave the power on 24/7… all the connections underneath my Aristo switches dissolved. I did just pull up a piece of track that apparently was moist all the time and the web had rusted/corroded/eaten away. (I’m all stainless Aristo)

Greg

Ouch! Maybe I should re-think using the rails as a power buss, or at least the amount of time I leave it powered up. When it is very wet my power supply shuts down due to over-current draw then ‘flashes’ ever 5 seconds or so to test if the short has been removed. I’ll flip the timer switch off when I notice this. Maybe a rain sensor in the lighting circuit would be something to consider.

OK maybe my rust was different…

I won’t doubt you.

Probably not any different. I didn’t seal it an the rust would not really penetrate the concrete to any degree. Probably just washed away over time. On the ballast it was just on the surface. Rain and wind move the ballast around so it probably just migrated away to where it was no longer prominently visible.

This staining is a LOT heavier. It may last the summer.

I think that is because the galvanic action was following the path of the electricity. Interesting, I would guess that your power supply is not floating, but one side is grounded, and I would guess it is the minus side.

You might check your 12v power supply, normally you would want it floating.

Greg

Greg Elmassian said:

I think that is because the galvanic action was following the path of the electricity. Interesting, I would guess that your power supply is not floating, but one side is grounded, and I would guess it is the minus side.

You might check your 12v power supply, normally you would want it floating.

Greg

It may be. The supply is a cheap Chinese made commercial LED supply salvaged from a sign that was taken out of service. I have several other supplies connected to the track which may or may not add to the ground path. I would need to isolate the lighting supply being used to test your theory. So, to check this would you measure continuity to earth ground from the supply output, or would a current measurement be helpful? I have good earth ground from my ham radio gear available near at the supply. I could always put a bulb (or my meter) between earth and the supply to see if I get current flow.

Yep, just stick one probe on the plus side, and the other to your AC ground, or any other good earth ground.

Greg

I would check from the plus side to ground, and if that doesn’t show on your meter as a path, then check from the negative side to ground. I have worked on some equipment where the chassis isn’t the negative rerun to the supply, its the positive return to the supply.