Rust Never Sleeps: Prioritize corrosion control to lengthen an asset's lifespan.

• Author: Orr, Vanessa

Just as the wood siding on a house will deteriorate if it is not painted or treated, the steel used in pipelines, buildings, machinery, and more will corrode if not protected from the elements. The most common cause is electrochemical reactions. Galvanic corrosion is when different kinds of metal are in contact with one another; electrolytic corrosion occurs most commonly when water becomes trapped between two conductors that have an electrical voltage between them, creating an electrolytic cell.

"There are four elements to a corrosion cell; anode, cathode, electrolyte, and a metallic path. The goal is to try to reduce or eliminate one of the four items that makes up that cell," explains Cynthia Cacy, corrosion control engineering principal at Coffman Engineers. "Applying a coating, for example, removes the metal from contact with the electrolyte, or you can change the corrosion cell by introducing a cathodic protection system."

For the latter case, Cacy gives the example of a water tank in someone's home that has an anode screwed into the top of the tank. Because the anode is more reactive than the steel of the tank, it will corrode preferentially instead of the tank corroding.

"A cathodic protection system can be applied to any metallic structure, including pipelines, docks, offshore platforms, and tanks," she explains. "Boats have cathodic protection systems, and there are companies that specialize in designing cathodic protection systems for bridges."

Depending on the object that needs to be protected, there are different corrosion control methods or approaches. In some cases, corrosion can even be prevented by choosing a noncorrosive material during the design stage.

"In older homes with copper piping, homeowners may experience pinhole leaks, which can become a nightmare," says Cacy. "Newer construction uses various forms of plastic pipe that aren't susceptible to corrosion."

Knowing what kind of systems can help prevent corrosion is a specialty of Coffman Engineers, which provides cathodic protection system design. commissioning, monitoring, and maintenance for new and existing structures for the oil and gas industry, water/wastewater, federal, utility, and commercial markets.

"We do this as part of the design process," says Cacy, adding that each client may also have its own specific guidelines or regulations that are required for corrosion control.

"The types of coatings recommended can depend on where you are putting the structure...