Aiming at the problem that the accuracy of remaining thickness of the field signature method (FSM) is ±(10%~15%) of the wall thickness in pit corrosion and should be modified by empirical coefficient,a new method was proposed to calculate the remaining thickness in FSM using the mathematical model of resistor network, which was based on the analysis of change of current field in monitoring area. The corrosion of pipe can be equivalent to the change of resistor between probes, and a single resistor network can be determined by the distance and amount of probes in monitoring area of pipe. The current of resistor can be calculated before and after corrosion with Kirchhoff’s law. The function relation of resistor before and after corrosion is established,and the formula of remaining thickness in high accuracy is obtained after the factor of change of current field is eliminated. The simulation in finite element analysis software and experiment results showed that the new algorithm of remaining thickness of pit corrosion is much higher than the algorithm commonly used at present in accuracy, and don’t need to modify by empirical coefficient, which showed that the efficiency calculation method is practical.
