摘要:
This invention, which pertains to the field of testing of the corrosion-resistance of materials, includes devices (a probe formed by a permanent reference electrode with corrosion coupons and an electronic switch) and a measurement method for evaluating the probability of corrosion of buried ducts due to alternating current (AC), and aims at providing a methodology that eliminates ohmic losses and allows the desired measurement to be obtained. For that purpose, a probe formed by a permanent copper or copper sulphate reference electrode (ECSC) with four corrosion coupons was developed, and an electronic switch which was also developed within the scope of this invention is coupled to this probe. This assembly (probe and switch), associated with a preferably portable digital oscilloscope or a data acquisition device with digital signal processing (DSP), makes it possible to obtain the waveform of the pipe/ground potential AC+DC off, and hence the peak potential of this waveform, this value being used to predict the corrosion of buried, cathode-protected ducts due to alternating current, on the basis of the criterion that corrosion due to alternating current will not occur or will be insignificant if the peak of the waveform of the pipe/ground potential AC+DC off is more negative than −0.85 VECSC. The present invention can also be directly used for monitoring external corrosion of ground ducts and to verify the real cathode protection potential of these ducts. In order to ensure the integrity of the ducts, this equipment can be installed at test points, at valve boxes and cathode protection rectifiers, as well as in zones where corrosion is suspected.