METHOD FOR CALCULATING DEPTH OF PITTING CORROSION

PURPOSE:To accurately and nondestructively estimate the depth of pitting corrosion caused by local corrosion by installing a plurality of monitoring device to heat exchangers or pipelines and subjecting the current value of each monitoring device to an extremal statistic process. CONSTITUTION:Local monitors are respectively provided at the downstream joints 1B-3B of liquid sump sections of sample tubes 1-3. The local monitors are respectively provided with sensor sections 1a-3a and ammeters 1c-3c. Then testing water contained in a testing water tank 10 is circulated through a pipeline 18, tube 1, pipeline 20, tube 2, pipeline 22, tube 3, and pipeline 24 by means of a pump 18A by adjusting the flowing speed of the testing water in the tubes 1-3 to prescribed values by means of a flow meter 18C. Thus anode currents flowing to the lead wires 1b-3b of the local corrosion monitors are measured with the ammeters 1c-3c. When estimated depths of pitting corrosion found from a model formula of pitting corrosion by using the measured anode current values are subjected to extremal statistics, the maximum depth of pitting corrosion can be estimated.