Rust: The Slow Burn
I once heard someone describe life as “a slow burn”. The speed of the burn probably depends on your lifestyle. I like rat rods and steam punk, neither of which necessarily translates to a fast lifestyle. Common to both - and in both cases, desirable - is rust.
Rust is a slow burn. It’s the oxidation of the host, and the elements involved determine the burn rate.
Rust vs. Corrosion
Rust is a term typically used to describe the oxidation of iron. Corrosion is a more general term used to describe the wearing down, or oxidation, of metals or surfaces. The fading of a painted surface is a form of corrosion. The green patina on copper is corrosion. The hazy surface on aluminum and stainless steel is corrosion, but a desirable corrosion that provides protection. If that surface gets scratched, the corrosion layer has to regenerate itself. Weathering, or Corten, steel is the same way. It’s covered with red rust that acts as a protective layer.
There are very few things that need to be present for rust to occur. There is the host, of course. After that, moisture and oxygen or hydrogen is all that is required for rust to begin. Other things like salt, UV, abrasion, stray electrical currents, temperature, stress and/or fatigue, and chemicals are merely accelerants of the process.
The Transition/Corrosion Zone
Almost anywhere you walk on this planet; there is a corrosion zone beneath your feet. Depending on how dry or wet, and how sandy or rocky the soil is, there exists enough moisture AND oxygen to cause corrosion. In a large portion of the United States, the corrosion zone is between 24 and 36 inches deep. For the rest of the earth’s surface, which is covered in water, the corrosion zone is that area where air and water coexist in waves and tides throughout the day.
The BIG PROBLEM!
Almost everyone wants renewable energy. Right now in the U.S. there are thousands upon thousands of acres of solar farms being built. A large portion of that construction is to take advantage of tax credits offered by the government, while they last. They are currently set to expire at the end of 2016, but that likely will not happen.
Solar panels are supported by a framework of galvanized steel, which rests upon galvanized steel embedded in the ground at varying depths. Galvanizing is a layer of zinc, about 3 to 6 thousandths of an inch thick. It’s called a sacrificial layer. It goes away. The folks in charge of this construction are relying on soil testing to determine if the soil is corrosive enough to warrant extra protection over the galvanizing, but who sets the limit, and what is it?
The builders of solar farms are either relying on this artificial corrosivity limit in the soil and deciding that corrosion protection isn't needed, or they're kicking the can down the street for someone else to worry over. Rust and corrosion will happen, and the farms will begin to fail because of it.
“…moisture and oxygen or hydrogen is all that is required for rust to begin.”
Experts within the utility industry have been sounding a warning for the over a decade now about the “coming Tsunami” - a red tsunami, if you will - of failures because of poor planning when it comes to corrosion management. Much of the infrastructure in the U.S. is decades old, and it was installed when designers didn’t know what is known now about rust and corrosion. It’s not just about solar farm pilings: Steel towers and utility poles, oil & gas pipeline and structures, cell towers, irrigation systems, traffic signal and signage structures - they can all fail because of…
moisture and oxygen...and a failure to plan.