Cast Iron Gate Valve VS Cast Steel Gate Valve

Let’s explore the characteristics of both cast iron gate valves and cast steel gate valves, and highlight when and why you should use each.

What is a Cast Iron Gate Valve

A cast iron gate valve is a type of gate valve made primarily from grey cast iron or ductile iron. These valves are recognized for their good compressive strength, excellent machinability, and vibration-damping properties. They are most often used in low-pressure and non-corrosive applications.

Key Features

• Material: Grey cast iron or ductile iron

• Pressure rating: Typically PN10–PN16

• Temperature range: Up to 200°C (392°F)

• Coatings: Often epoxy-coated for corrosion protection

• Connection type: Flanged ends (standard for water systems)

Advantages:

• Cost-effective for large systems

• Excellent damping of vibrations

• Easy to manufacture in large sizes

• Suitable for clean water and air systems

Despite their benefits, cast iron gate valves are more brittle than steel, which can limit their use in applications with temperature fluctuations, high pressure, or mechanical shock.

What is a Cast Steel Gate Valve

A cast steel gate valve is made from carbon steel or alloy steel through the casting process. Known for their superior mechanical strength and resistance to high temperatures and pressures, these valves are ideal for demanding industrial and marine environments.

Key Features:

• Material: Carbon steel (e.g., ASTM A216 WCB) or alloy steel

• Pressure rating: PN25–PN100 or ANSI Class 150/300/600

• Temperature range: Up to 425°C (797°F) depending on material

• Corrosion resistance: High, especially with stainless steel trim or coatings

• Ends: Flanged, welded, or threaded

Advantages:

• Excellent tensile and impact strength

• Withstands thermal cycling and pressure surges

• Better ductility and shock resistance than cast iron

• Longer service life in harsh conditions

Cast steel gate valves are widely used in marine valve systems, where saltwater corrosion, high pressure, and continuous operation are key concerns.

When To Choose 

Choose cast iron gate valves when

• You are working with water or air systems at low pressure.

• You want an economical solution for a non-aggressive environment.

• Your application involves large-diameter pipelines with limited stress exposure.

Choose cast steel gate valves when

• The system operates under high pressure or high temperature.

• You need greater mechanical strength and corrosion resistance.

• The application involves steam, oil, gas, or saltwater.