A new design of storage tank with a hollow pontoon is proposed. A toroid-shaped component and a hermetically secured flexible sealing strip are located about the perimeter of the pontoon. The pontoon and its toroid-shaped component are filled with an inert gas. The pontoon design fully prevents loss of oil products during various technological operations such as filling of the tank or the draining of oil products, as well as during the prolonged storage of oil products in the tank under various climatic conditions, etc.