Figure 1: Gate valve
Plug and gate valves are both stop-valves suitable for a wide array of applications and media types. For example, they can both be used for clean media and media containing solids or stringy material. Therefore, it may be difficult to determine which is more suitable for a specific application. This article looks closer at the similarities and differences between gate valves and plug valves to help ensure the correct valve is chosen and used for varying applications.
Before deciding between the two valves, it is important to consider the following:
Plug and gate valves are named after the method that each uses to allow or block flow. A plug valve uses a plug with an opening running through it. When a gate valve is closed, its disc sits perpendicular to and blocks the flow, operating much like a gate.
Plug valves are quarter-turn valves, meaning the valve stem needs to turn only 90° for the valve to fully open or close. With mechanical lever actuation (pneumatic and electrical actuation are also possible), the valve’s lever is turned 90° to accomplish this. When turned on, the opening in the plug is in line with the ports, and media can flow through the valve. Closing the valve rotates the plug, so the opening is no longer aligned with the ports, and the plug’s body blocks the flow.
Gate valves are multi-turn valves, meaning the valve stem needs to turn more than 360° for the valve to fully open or close. Therefore, a gate valve closes significantly slower than a plug valve. Turning the valve’s handwheel (mechanical actuation) can raise or lower the disc within the valve’s body. Fully raising the disc allows media to flow unobstructed, and fully lowering the disc blocks the media. Discover more by reading our gate valve and plug valve articles!
Figure 2: Plug valve
The four distinguishing design characteristics of a plug valve are the plug shape, plug opening, whether the valve is lubricated or non-lubricated, and the number of ports.
Beyond how to actuate a gate valve (mechanically, pneumatically, or electrically), the primary distinguishing design characteristics are the valve’s disc, how the bonnet connects to the valve body, and whether the stem is rising or non-rising.
There are many materials available for plug and gate valves, so finding the right material for an application is possible. Learn more by reading our chemical resistance guide!
Plug valve Gate valve Installation space Requires less space but has a long handle relative to valve size that must be considered Requires more space, particularly space above for rising stem valves Response time Quarter-turn valve, faster Multi-turn valve, slower Operation frequency Designed for more cycles Designed for infrequent cycles Leakage Can provide a bubble-tight shutoff Strong sealing capabilities except for low-pressure systems Corrosion/Wear Less corrosion and wear on the stem because it doesn’t sit in the flow path. May cause water hammer if incorrectly operated. The stem sits in the flow path and will experience more corrosion and wear Pressure Excellent design for low-pressure systems More suitable for high-pressure systems and may leak if used in low-pressure systems Temperature Lubricated plug valves are more suitable for high-temperature applications than non-lubricated plug valves Suitable for higher temperature systems but check with the manufacturer as too high of temperatures may warp the valve body, which will cause the disc and seats to become unaligned Flow control Provides on/off functionality and diamond opening plug valves can throttle flow Can only provide on/off functionality. Throttling flow will damage the valve. Flow restriction/Pressure drop Plug valves with restricted openings cause some pressure drop, full-bore plug valves are available Full-bore valve, pressure drop is insignificant Flow capacity Lower Higher Flow direction Bidirectional and multiport Bidirectional Power requirement Higher under high pressure Lower under high pressure Torque High, especially under high pressure LowA plug valve’s plug opening can be full bore but is also available in reduced flow for applications where pressure drop is not a large concern.
A big difference between a gate and plug valve is that a gate valve is multiturn, and a plug valve is quarter-turn. So a plug valve can be opened or closed faster than a gate valve.
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