A tapping valve with a plastic valve housing for shipping and storage tanks for liquids, which are equipped with an inner tank with a filling socket and a drain socket for connecting the tapping valve, an outer jacket of a metal cage or sheet metal, and a pallet-like metal support frame. The tapping valve is screwed by means of the inlet socket of the valve housing onto a connecting flange, which is designed as a threaded flange, is made of an electrically conductive plastic material, and is welded onto the drain socket of the inner tank. The connecting flange of the valve housing is connected with the support frame or the outer jacket of the shipping and storage tank by an electric grounding conductor.