In order to protect the environment as much as possible, it is indispensible to monitor tanks containing substances which are harmful to water, such as hydrocarbons, and other insidious leaks. When new tanks are designed, such a monitoring system should be designed into the new construction. Existing tank storage systems should be modified and subsequently fitted with adequate monitoring systems.
In a state of the art method, intermediate floors are welded into existing flat bottomed tanks. The chamber produced in this way is evacuated or kept at a pressure below atmospheric pressure. If a leakage occurs, it can be detected at an early stage by monitoring the pressure difference.
The state of the art solution, however, is rather complicated because the inner bottom must be of a very stable construction capable of withstanding high loads. When modifying existing flat bottomed tanks, first a bitumen layer has to be applied onto the tank bottom, then a first sheet metal floor is welded into the tank, followed by a second welded floor, leaving a chamber between the two. The latter floor has to be welded in because the primary tank bottom is susceptible to corrosion from outside and can therefore not be used to create the chamber. This process is very cost-intensive and technically complicated. A major shortcoming is the fact that the location of the leakage cannot be detected.
Furthermore, there is a state of the art process for detecting leaks wherein a sensor tube is laid out horizontally in relation to the tank bottom. The sensor tube is laid in a perforated protective tube and consists of a gas-permeable material. In certain time intervals, such as 24 hours, gas samples are taken and analyzed. This means, however, that the occurrence of a leakage is not immediately detected and thus it is not possible to trigger an alarm immediately. The gas analyses require complicated measuring instruments which are expensive and sometimes even unrealiable, because the gas samples often have to be conveyed over quite long distances, which may change their composition.
There is a need for a process for monitoring flat bottomed tanks for leakages. This process must allow for easy modification of existing tanks, must work reliably and localize a leakage without delay, upon its occurence. Furthermore, the measuring process should be as simple as possible.