Cast iron butterfly valves, commonly referred to as gray iron butterfly valve, are made of an alloy containing iron and 2-4% carbon, and may contain trace amounts of other impurities like sulfur or phosphorus. The cast iron butterfly valves are a cheap option for non-critical applications.

The cast iron butterfly valves are not new. Cast iron has been known for centuries, and it’s known as a very durable material for butterfly valves. It has excellent damping qualities, meaning that when intense vibrations disturb the cast iron butterfly valve, it is unlikely to suffer any damage. However, the cast iron butterfly valves have low ductility.

It is normally impractical for marine use butterfly valves because pipes and valves tend to bend slightly as a ship moves on water, and this can cause the iron to crack. In fact any bending of the material of these butterfly valves will cause it to crack.

These types of cast iron butterfly valves are most commonly used in applications that require high amounts of flow along with quick, tight shut off. Some applications include hot and cold domestic water, HVAC, condenser and chilled water. These applications are often found in commercial or light industrial utilities.