What is the purpose of thread sealant and where would you apply it?

• A. To lubricate threads for easier assembly; apply on all threads.
• B. To color-code connections for identification; apply on exterior threads.
• C. To seal thread joints so fluids do not leak; apply on mating threads of pipes or fittings where specified in the TM.
• D. To clean surfaces before sealing; apply to dry surfaces.

Answer: (C)

Thread sealant’s job is to prevent leaks by filling the tiny gaps that exist between mating threaded joints. It’s not a lubricant, nor is it used for color-coding or cleaning. You apply it only to the threaded portions that will engage to seal the joint, and only where the Technical Manual specifies. This ensures you use the right product and the correct amount for the particular pipe or fitting, and it keeps sealant away from surfaces that shouldn’t be sealed or from the bore where debris could cause problems. Follow the TM’s guidance on where and how to apply (and which type to use), then assemble and tighten to the required specification.