Which type of pipe is not permitted for use under NFPA 13D?

The correct choice regarding the type of pipe not permitted for use under NFPA 13D is aluminum pipe. NFPA 13D specifically governs the installation of sprinkler systems in one- and two-family dwellings and certain townhouses. This code restricts the use of aluminum piping due to its susceptibility to corrosion and its lower strength compared to other materials, particularly under certain environmental conditions.

Steel pipe, plastic pipe, and CPVC (Chlorinated Polyvinyl Chloride) pipe are accepted materials under NFPA 13D, as they meet the required standards for durability and resistance to fire. Steel pipe, while heavier, offers excellent strength and longevity; plastic pipe is lightweight and easy to install; CPVC is favored for its ability to withstand higher pressures and its resistance to corrosion. Each of these materials has specific applications and advantages that comply with the requirements outlined in the NFPA standards, making aluminum the only material listed that does not meet the criteria for use in these residential sprinkler systems.