After installation, bolted joint accessories must be cleaned and coated with which material?

The correct answer is the use of asphalt or another corrosion-retarding material for coating bolted joint accessories after installation. This option is critical for protecting the durability and functionality of the joints from adverse environmental conditions.

Bolted joints in fire service mains are exposed to moisture, soil, and various chemicals, which can lead to corrosion over time. A coating of asphalt or a similar material creates a protective barrier that helps prevent moisture ingress and chemical reactions that could compromise the integrity of the joint. This ensures reliability and effectiveness in the fire protection system over its lifespan.

Using materials that specifically retard corrosion is essential in maintaining the safety standards outlined in NFPA 24. Coatings that are not specifically designed for corrosion prevention could lead to premature failure of the joints, thereby jeopardizing the integrity of the fire service mains.