A closure fitting for a PET keg comprising a cover with a central opening, the fitting comprising: means of connection configured to connect with a keg neck, a hollow rod , a valve element with a central valve opening, a spring , a ring nut , wherein the first end of the rod is made open and the second end of the rod is made closed and fitted with a collar step , the surface of the rod having at least one rod opening , wherein the valve element which is configured to move along the rod is installed on the rod , the central opening of the valve element has an inner collar recess which is configured to engage with the collar step of the rod and an external collar recess which is configured to engage with a collar step of the cover , and the spring is installed between the valve element and the ring nut , wherein the cover is made in the form of a mushroom comprising a stem and is connected to the ring nut using a threaded fastener for direct installation of the fitting on the keg neck, wherein openings for gas passage are provided at the bottom of the ring nut , a ring gasket is placed between the shoulder of the cover and cylindrical surface of the stem of the cover to seal the connection between the cover and the keg neck, wherein the valve element is made of polymeric material with a Shore hardness of 40-60 and is configured to function both as a safety relief valve and as an operation indicator, characterized in that the valve element comprises at least one non-through channel with the diameter of 3 to 5 mm open on the bottom side and bounded by a thin material layer with the thickness of 0.2 to 1.5 mm on the top side. means of connection configured to connect with a keg neck, a hollow rod , a valve element with a central valve opening, a spring , a ring nut , wherein the first end of the rod is made open and the second end of the rod is made closed and fitted with a collar step , the surface of the rod having at least one rod opening , wherein the valve element which is configured to move along the rod is installed on the rod , the central opening of the valve element has an inner collar recess which is configured to engage with the collar step of the rod and an external collar recess which is configured to engage with a collar step of the cover , and the spring is installed between the valve element and the ring nut , wherein the cover is made in the form of a mushroom comprising a stem and is connected to the ring nut using a threaded fastener for direct installation of the fitting on the keg neck, wherein openings for gas passage are provided at the bottom of the ring nut , a ring gasket is placed between the shoulder of the cover and cylindrical surface of the stem of the cover to seal the connection between the cover and the keg neck, wherein the valve element is made of polymeric material with a Shore hardness of 40-60 and is configured to function both as a safety relief valve and as an operation indicator, characterized in that the valve element comprises at least one non-through channel with the diameter of 3 to 5 mm open on the bottom side and bounded by a thin material layer with the thickness of 0.2 to 1.5 mm on the top side. <EOS>