Microwave Nondestructive Evaluation and Characterization of Tank Inner-Liners

Abstract

Tanks containing caustic and hazardous materials are found in many industries. For example, the petro-chemical industry uses tanks for containment of a variety of potentially hazardous liquids, in both mobile (railroad and truck transport) and fixed site installations. Most tanks contain an inner-liner that is intended to protect the exterior structural vessel containing the liquid. If this inner-liner is damaged the caustic/corrosive liquid may attack the exterior tank which can then result in leaks and serious damage. Inner-liners in railroad tank cars intended to transport caustic liquids are typically inspected using a high-voltage „spark“ test to check their condition. This method suffers from a number of serious limitations. We have performed a series of experiments using a new approach employing near-field microwave NDE techniques to measure and determine the integrity of tank innerliners. It will be shown that this advanced technique can effectively detect and characterize a variety of inner-liner defects including damage such as cuts or breaks, dis bonds between the inner-liner and exterior tank, and incursion of liquid between the liner and tank. The method can also be used to determine the efficacy of required repairs. It is important to note that this approach can be used for all types of tank liners as long as they are non-conductive, such as rubber, polymer, plastic, paint, etc.