Improved formula for localized corrosion using field signature method

•We analyzed the low detection accuracy of localized corrosion in FSM.•An improved formula was proposed to assess localized corrosion.•The detection accuracy of localized corrosion can be greatly improved by this new formula.

Field signature method (FSM) is based on a potential drop (PD) technique and has been applied for nearly three decades for online metal pipe corrosion monitoring in many industrial areas. However, the detection precision of FSM for localized corrosion is still very low because the current field distribution in the measured pipe will be changed during the corrosion process but the formula used to assess corrosion-depth at present ignores the changes. This paper proposed an improved formula to calculate localized corrosion. The theoretical analysis and experimental results verified that the evaluation accuracy of FSM for localized corrosion can be greatly improved by this new formula.