A water corrosivity sensing system is currently under development that has the potential to combine the strengths of rate measurement techniques such as linear polarization resistance with longer-term cumulative damage measurements typically provided by electrical resistance probes.  This sensor technology is applicable not only to water pipeline systems, but a broad range of liquid and gas piping systems used in military facilities as well as electric power, chemical, pulp and paper, and fossil fuel industries.

The corrosion sensing system operates on a diaphragm-based principle, where the diaphragm is a sacrificial element that corrodes as the pipeline.  Minute changes in diaphragm thickness can be detected by monitoring the diaphragm response to applied pressure.  Diaphragm response, as with traditional pressure sensors can be measured by any number of methods, including resistive strain gage, capacitive, and optical interferometry.  The current sensor embodiment described in this paper uses a high-resolution optical approach to determine the effective diaphragm thickness loss.  This development effort will culminate with a field demonstration of the prototype sensing system installed in an Army trial facility.

This paper describes the operational principle of the sensing elements, which is based on observing the mechanical response of the sacrificial element to the applied pipeline pressure.  Sensor design and fabrication considerations are presented along with the experimental hardware used to conduct the laboratory tests.  A brief discussion of the signal processing strategies is followed by representative accumulated corrosion test results.