Cast iron valves or ductile iron valves, which is better?

Customers in all industries require a variety of valves to meet their demanding processes. Valves are available in a wide range of materials for any conceivable application. Some of these materials are PVC, carbon steel, stainless steel, cast iron, and ductile iron. This article focuses on cast iron valves and ductile iron valves.

Cast Iron Valves

Cast iron (also known as gray cast iron) is a metal that has been used for centuries. Cast iron is strong and usually does not break even after severe vibration. It is an alloy made of 96-98% iron, 2%-4% carbon, and a small amount of silicone. It has impressive temperature tolerance, with some cast irons able to withstand temperatures in excess of 2100F (1150C). In terms of pressure, the strength of cast iron depends on its pressure rating. The two most common are Class 125 and Class 250. At less extreme temperatures, Class 125 cast iron flanges are rated between 150 and 200 psi. Class 250 cast iron is much harder and is rated from 300 to 500 psi. these pressures will vary by end type. The main disadvantage of cast iron valves is that they are not very ductile at all.

Ductile Iron Valves

Ductile iron is a synthetic metal material invented in the mid-twentieth century as a type of iron used to make cast iron. By adding trace amounts of other elements to the iron, the carbon is made to form a spherical shape instead of flakes. This is what allows the material to change without fracturing. Ductile iron has excellent ductility, so it will not necessarily fracture when bent. Temperature limits are slightly lower than cast iron, but still quite high at 1350F (730C). In terms of pressure, ductile iron valves are also available in pressure grades: 150 and 300. 150 grade ductile iron can maintain a seal up to 250 psi at standard outdoor temperatures. 300 grade can withstand pressures up to 640 psi.

Differences

Installation

◑ Cast iron: This material offers the user many options when it comes to installation. Cast iron valves are typically flange bolted. Welding is difficult, but not impossible. Our cast iron valves are available with flanged ends, as this is an excellent method for high or low pressure applications.

◑ Ductile Iron: Ductile iron offers many of the same installation options for the user because of its similar construction to cast iron. Welding is not recommended, but bolting with flanges is still the best option for most applications.

Cost

◑ Cast Iron: The manufacturing process for cast iron valves is simpler than for ductile iron valves, which can save you a lot of money. If you don't need the additional benefits that ductile iron offers, cast iron is the smart choice.

◑ Ductile Iron: Ductile iron is the more expensive option, but for good reason. In many cases, it offers significantly better properties than cast iron.

Durability

◑ Cast iron: Cast iron is a strong material that can withstand higher pressures than any plastic. However, when a cast iron valve or pipe exceeds its pressure rating, it will bend and break. Cast iron has almost zero ductility, which means it is rigid and will break if bent. Cast iron also rusts over time, so regular maintenance is necessary to prevent valve corrosion.

◑ Ductile iron: Ductile iron also has impressive structural integrity. It can withstand high pressures and temperatures without retreating. Due to its ductility, the

This material is also less likely to crack when bent. Over time, ductile iron will also rust, but not as easily as cast iron.