A gate valve is the point of access to a fluid flow. When open, the gate valve allows a full flow in a pipeline. When fully closed, the valve shuts the flow off.
Typically, gate valves are most effective in either a fully open or a fully closed position. They cannot regulate the flow or pressure of fluids, and they also cannot be kept partially open. Keeping a gate valve partially open can also cause damage to its parts.
To open or close the gate valve, one will have to turn the wheel handle many times. Thus, a gate valve lockout tagout lock has to fit over the handle to keep it from turning.