How many linear feet of well-coated 2-inch nominal diameter steel pipe can be protected for 20 to 30 years by two standard 17-pound magnesium anodes?

The correct choice indicates that two standard 17-pound magnesium anodes can protect approximately 1000 linear feet of well-coated 2-inch nominal diameter steel pipe for a duration of 20 to 30 years. This assessment is based on the principles of cathodic protection, where magnesium anodes corrode preferentially, providing a protective barrier against corrosion for the metal pipe.

In a cathodic protection system, the anodes function by sacrificing themselves in the electrochemical process, allowing the steel pipe to remain intact and undamaged over an extended period. The selection of magnesium as the anode material is relevant because it is highly effective in galvanic corrosion protection and provides sufficient galvanic current over the expected lifespan of 20 to 30 years under typical conditions.

Calculating the linear footage that can be protected involves understanding several factors, including the size of the anodes, the environment in which the pipe is placed (such as soil resistivity), and the condition of the pipe coating. The standard 17-pound anodes are designed with a specific current output, which is sufficient to protect a certain amount of pipe length.

Overall, the fact that 1000 feet is a standard industry estimate for this type of installation reflects a balanced approach to