Neoprene washers are used with sheet metal and lagging to provide

• A. Watertightness
• B. Thermal resistance
• C. Electrical insulation
• D. Air sealing

Answer: (A)

Neoprene washers act as flexible gaskets, creating a compressible seal between sheet metal joints and the surrounding lagging. When you tighten the fittings, the washer deforms to fill small gaps, blocking moisture from getting behind the metal and insulation. That moisture exclusion is what gives the joint its watertightness. Neoprene brings elasticity and water resistance to the seal, so it remains effective even as materials expand or contract with temperature changes. While neoprene has other useful properties, the primary purpose in this context is to prevent water leaks, not to provide major thermal resistance, electrical insulation, or air sealing.