Abstract: A lock and support device for fuel tanks holding acetylene gas and the like. The lock and support device includes an outlet cap, a locking bar, and an intermediate lock connecting ring that is connected between the outlet cap and the locking bar. The outlet cap screws over the outlet of the valve that is permanently attached to the top of the fuel tank in order to connect the lock and support device to the fuel tank and to cover the valve outlet. The locking bar may be used as a handle and as a means to prevent removing the outlet cap. The lock connecting ring is used as a means to support the tank in an upright position, and as a connection means for locking the tank to a fixed object.