What should you put on valve stem threads?

• A. Thread tape
• B. Lubricant spray
• C. Grease
• D. Oil

Answer: (C)

Lubricating valve stem threads with grease keeps the moving parts operating smoothly and helps prevent seizing, galling, and corrosion in the salty, humid shipboard environment. The grease forms a protective film on the threads, reducing friction as the stem turns and aiding future disassembly. It also helps preserve the sealing surfaces so the valve can be opened and closed reliably over time. Thread tape is for static pipe threads and isn’t suitable for the small moving interface of a stem; it can contaminate seating surfaces. A spray lubricant or oil tends to wash away or drip and may not stay on the threads where you need lasting protection. Grease stays put and provides the right balance of lubrication and protection for valve stem threads.