Gasket materials for gas flanges must be full-faced and be made of which materials?

• A. Bronze and cast iron
• B. Rubber and neoprene
• C. Aluminum and steel
• D. Copper and brass

Answer: (A)

In gas flange connections, a full-faced gasket is required to seal the entire mating surface and distribute the bolt load evenly, preventing leaks at the edges or through small gaps. The gasket material must be able to withstand the gas environment and mating flange materials without degrading.

Metallic gaskets made from bronze or similar copper alloys, paired with cast-iron flange faces, are well-suited for natural gas services because they resist corrosion and keep a reliable seal under the temperatures and pressures typical in gas piping. Bronze offers good resistance to gas contaminants and cooperates well with iron or steel flange faces, while cast iron is a common, compatible flange material in gas systems.

Elastomeric gaskets such as rubber or neoprene can degrade in gas service and with varying temperatures, making them less reliable for many gas-flange joints. Other metal pairings (like aluminum/steel or copper/brass) don’t provide the same proven combination of compatibility, durability, and seal integrity for these flanges.

So the better choice aligns with using a full-face metal gasket from bronze and cast iron, which supplies a durable, leak-tight seal appropriate for gas piping.