The present invention relates to methods for preventing corrosion of the vessel, made of a corrodible material, of a storage tank, in particular of buried storage tanks, as well as to storage tanks equipped with devices for checking the vessel which use these methods.
Methods and devices are known for leak detection in a storage tank. For example the French Patent No. 1,551,051 which describes a vessel which includes an inner skin, a liquid-presence detector being arranged on the inner surface of the bottom of the vessel. This type of device exhibits the drawback, on the one hand, of not protecting the outer surface of the vessel from corrosion resulting from the moisture outside the vessel and, on the other hand, does not make it possible to detect the appearance of water as soon as it occurs in the intermediate space. The document Patent Abstract of Japan, Vol. 8 Number 68 (page 264) of Mar. 30, 1984, also describes a vessel surrounded by a concrete wall, a recess having been formed in the gap between the concrete wall and the vessel, in which a water detector is arranged. However, this device exhibits the drawback of not warning the user of the appearance of moisture as soon as it appears, but, as in the case of the device described in French Patent No. 1,551,051, only after a certain time during which the corrosion may already have progressed too far.
A method is known for checking the good condition of the vessel of a buried storage tank, which consists in observing the appearance of corrosion on the outer wall of the vessel by using a camera, the images from which are sent to a monitor which is not buried. This method of the prior art exhibits the drawbacks, on the one hand, of being very expensive and, on the other hand, of not giving a warning until after corrosion has occurred.