Abstract: A method of detecting a locally generated corrosion of a first metal element when exposing the first metal element (2) to a corrosive environment. A first surface of the first metal element (2) is exposed to the corrosive environment. A sponge (3) is sandwiched between the first metal element (2) and a second metal element (4). The sponge (3) constituting in dry state an electrical insulator and constituting an electrical conductor when wetted in the corrosive environment. An electrical insulator together with the first metal element (2) encapsulates the second metal element (4) and the sponge (3) for preventing the second metal element (4) and the sponge (3) from being directly exposed to the corrosive environment. An impedance between the second metal element (4) and a ground electrode is measured, and a decrease in the impedance from an infinite impedance to a finite impedance caused by a pinhole being generated in the first metal element (2) is monitored.

Abstract: A method of detecting a locally generated corrosion of a first metal element when exposing the first metal element (2) to a corrosive environment. A first surface of the first metal element (2) is exposed to the corrosive environment. A sponge (3) is sandwiched between the first metal element (2) and a second metal element (4). The sponge (3) constituting in dry state an electrical insulator and constituting an electrical conductor when wetted in the corrosive environment. An electrical insulator together with the first metal element (2) encapsulates the second metal element (4) and the sponge (3) for preventing the second metal element (4) and the sponge (3) from being directly exposed to the corrosive environment. An impedance between the second metal element (4) and a ground electrode is measured, and a decrease in the impedance from an infinite impedance to a finite impedance caused by a pinhole being generated in the first metal element (2) is monitored.

Abstract: A method of diagnosing corrosion risk of a buried pipe due to DC stray currents and/or AC voltages induced in soil employs a metal probe including a first, exposed part having a first specific resistivity, and a second, sealed reference part having a second specific resistivity. The probe is buried in the soil, and the AC current and voltage between the pipe and the probe are measured, from which the spread resistance is determined. The resistances of the first and second probe parts are determined by respectively passing first and second excitation currents through the first and second probe parts and measuring the voltages across them. The resistance measurements are stored, and the steps are repeated periodically. The corrosion of the first probe part is determined from the measurements according to an algorithm, and the pipe corrosion risk is diagnosed from an empirical combination of the corrosion of the first probe part, the spread resistance, and the AC voltage measured.

Abstract: A method of diagnosing corrosion risk of a buried pipe due to DC stray currents and/or AC voltages induced in soil employs a metal probe including a first, exposed part having a first specific resistivity, and a second, sealed reference part having a second specific resistivity. The probe is buried in the soil, and the AC current and voltage between the pipe and the probe are measured, from which the spread resistance is determined. The resistances of the first and second probe parts are determined by respectively passing first and second excitation currents through the first and second probe parts and measuring the voltages across them. The resistance measurements are stored, and the steps are repeated periodically. The corrosion of the first probe part is determined from the measurements according to an algorithm, and the pipe corrosion risk is diagnosed from an empirical combination of the corrosion of the first probe part, the spread resistance, and the AC voltage measured.

Abstract: Apparatus for measuring accumulated and instant rate of material loss or material gain of metal elements for the detection of metal deposition and corrosion includes a metal probe that is inserted into a measurement environment, causing the probe to experience metal deposition or corrosion. The probe has a corrosion-resistant first section and a corrodible second section. A temperature-compensated circuit receives an input signal from each of the first and second sections of the probe, whereby the circuit maintains a substantially constant voltage across the first section and generates a reference signal and a measurement signal. The circuit conditions and converts the reference signal and the measurement signal to produce first and second digitized output signals for inputting to a microprocessor.

Abstract: The present invention relates to a method and an apparatus for measuring accumulated and instant rate of material loss or material gain of metal elements for the detection of metal deposition (material gain) caused for example during deposition of coatings used in plating processes and corrosion (material loss) caused for example in pipelines during transportation of hazardous media. The apparatus and the method provides means for measuring accumulated and instant rate of material loss or material gain by inserting a probe in a measurement environment causing a probe experience metal deposition or corrosion. Further the apparatus and the method provides means for performing a temperature independent measurement of accumulated and instant rate of material loss or material gain accomplished without use of a temperature sensor device.