Name two typical coatings used on underground steel pipelines.

• A. Fusion-bonded epoxy
• B. Coal tar epoxy
• C. Fusion-bonded epoxy and coal tar epoxy
• D. Cement-mortar coatings

Answer: (C)

Underground steel pipelines need a protective exterior coating to keep moisture and soil chemicals from corroding the metal. Fusion-bonded epoxy is a dry, powder coating that is melted onto the pipe, creating a uniform, highly durable barrier with strong adhesion. It stands up well to burial conditions and works nicely with cathodic protection, which is commonly used to prevent corrosion in buried pipelines.

Coal tar epoxy is another long-standing, robust coating option. It provides excellent moisture and chemical resistance and has a proven track record in harsh soil environments, making it a go-to choice for underground protection as well.

Cement-mortar coatings do appear in some installations, but they’re not as typical for modern underground steel pipelines as these two polymer coatings. That’s why fusion-bonded epoxy and coal tar epoxy are the two most common choices you’ll see in practice.