Gas valve with molded PTFE / flexible graphite as packing, opening and closing parts are plug shaped valve, sealing surface flat or cone, the valve along the centerline of the valve seat for linear motion, the packing gland provides the initial seal, when the wear caused by dynamic seal leakage, available packing gland nut adjustment. Gas valve used in the city of liquefied petroleum gas storage station, is also used in oil refineries, petrochemical plants, liquefied gas system of petrochemical plant, as the opening and closing device to control the gas medium.