Which of these valves is most commonly used for on-off applications?

The solid wedge disk gate valve is most commonly used for on-off applications due to its design and functionality. Gate valves, in particular, are intended to be fully opened or fully closed, which allows for minimal resistance to flow, making them ideal for applications where the goal is to shut off or allow fluid to flow without creating significant pressure drops.

The structure of a solid wedge disk gate valve features a disc that moves perpendicular to the flow, fully sealing when closed, which provides an effective seal against backflow. This feature makes it excellent for applications where damaging liquid or gas leaks need to be prevented.

While globe valves can regulate flow and are often used for throttling, they do not excel in on-off applications due to their design, which contributes to pressure drops when fully opened. Pressure relief valves serve a very different purpose, focusing on releasing pressure in the system rather than controlling flow in on-off scenarios. Corrosion-resistant valves are characterized by their materials and suitability for certain environments but do not specifically denote on-off functionality. Thus, the solid wedge disk gate valve stands out as the most appropriate choice for on-off control in piping systems.