Polarization resistance is particularly useful as a method to rapidly identify corrosion upsets and initiate remedial action, thereby prolonging plant life and minimizing unscheduled downtime. The technique is utilized to maximum effect, when installed as a continuous monitoring system. This technique has been used successfully for over thirty years, in almost all types of water-based, corrosive environments. Some of the more common applications are:
Cooling water systems
Secondary recovery system
Potable water treatment and distribution systems
Waste water treatment systems
Pickling and mineral extraction processes
Pulp and paper manufacturing
Hydrocarbon production with free water
The measurement of polarization resistance has very similar requirements to the measurement of full polarization curves. There are essentially four different methods of making the measurement according to whether the current or the potential is controlled and whether the current (or potential) is swept smoothly from one value to another, or simply switched between two values. In addition the measurement may be made between two nominally identical electrodes (a two-electrode system), or a conventional three-electrode system (working, reference and counter) may be used.
The principle of LPR measurements is explained in more details here, with a view of some of the fundamental pitfalls of the technique.