If _________ tie-rods are used for restraining pipe, they should be coated or covered for protection against corrosion.

• A. Stainless steel
• B. Brass
• C. Nonalloyed carbon steel
• D. Aluminum

Answer: (C)

When tying and restraining pipe in a water distribution system, protection against moisture and aggressive water chemistry is essential because the metal components are exposed to corrosion. Nonalloyed carbon steel has relatively low inherent corrosion resistance, so it needs a protective barrier to prevent rust and material degradation. Coating the tie-rods—such as with galvanizing, epoxy, or paint—or covering them with a protective sleeve keeps moisture and oxygen away from the steel surface, greatly extending their life and maintaining the strength of the restraining system.

Stainless steel would already resist corrosion and often wouldn’t require coating, which is why it’s not the recommended answer when focusing on the need for protection for carbon steel. Brass and aluminum behave differently in water systems and are not the typical choices for tie-rods in this context because of their own mechanical and corrosion considerations, making carbon steel the standard scenario where coating is needed.