Abstract: A cooling device for liquid cooling of at least one member of a welding device and a welding device with such a cooling device is described. The cooling device comprises a coolant tank, an outlet pipe for coolant from the coolant tank to the member, which outlet pipe comprises an outlet for connection to the welding device, a return pipe for returning heated liquid from the member back to the coolant tank, which return pipe comprises an inlet for connection to the welding device, and a pump which is connected to the outlet pipe for pumping coolant from coolant tank to the member. The cooling device comprises means for preventing flow through at least one of the outlet pipe and the return pipe when the pump is shut off.