Piping and fittings for clean agent systems are permitted to be welded. When listed threaded fittings are used, what method is followed to prevent leakage?

• A. Sealant on the female threads
• B. Joint compound, Teflon tape, or sealing lubricants are applied to the male threads
• C. Threadlocker on both sides
• D. No additional measures are required

Answer: (B)

In threaded piping connections for clean agent systems, the seal is created by applying a thread sealing material to the male threads before assembly. Joint compound, Teflon tape, or sealing lubricants fill the gaps between the threads and prevent leakage of the agent. Sealing on the male threads is essential because it directly seals the path where the gas would escape as the connection is tightened. Using sealant on the female threads is not typically effective and can risk contamination of the internal surfaces. Threadlocker is meant to prevent loosening of fasteners, not to provide a gas-tight seal for pipe threads. And of course, some sealant is required—no additional measures would leave leaks.