A gate valve lock is a lockout tagout device used to prevent access to a valve. Once a valve is turned off, a properly installed valve lock can keep it turned off. A lock like this has to be made of a durable material that can withstand extreme temperatures, chemicals, and other things found in industrial workplaces. The lock will thus be difficult to destroy.
In terms of design, a gate valve lock is made to almost completely cover a valve. When the lock is installed, it is essentially impossible to access the gate valve handle. Thus, it will also not be possible to turn the valve back on while the lock is installed.