Diaphragm-Based Pipeline Corrosivity Monitoring System

A water corrosivity sensing system is currently under development that combines 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 similarly to the pipeline.  Small changes in diaphragm thickness can be detected by monitoring the diaphragm response to the applied pressure intrinsic to the pipeline process.  Diaphragm response, as with traditional pressure sensors can be measured using any of several instrumentation strategies.  To date, Luna has designed and tested diaphragm corrosion sensors that operate using optical interferometric techniques and traditional electrical foil strain gages, each having inherent advantages depending on the intended application.  This paper contains details of the sensing element design and representative corrosion data for optical and resistive strain gage sensor variants.  The prototype system currently under development will be field demonstrated in an Army water system.