It's from a coupling or connector for a hose or flexible pipe called a camlok/cam lock. There's usually one on each side of the female end. The male end has a groove. The cam holds them in place. Tony
I agree with Icewing, hydrant handle. That symbol on it may even mean water. Tony has a great idea too, there's some of them around the plant here, I'll take a look.
It's from a coupling or connector for a hose or flexible pipe called a camlok/cam lock. There's usually one on each side of the female end. The male end has a groove. The cam holds them in place. Tony