Abstract: Field signature method (FSM) is a non-destructive testing technology widely used in metal pipeline defect detection. It can detect corrosion defects with high accuracy;but its detection capability for crack defects with higher risk coefficient is insufficient. In this paper,a multi-direction field signature method (MDFSM) is proposed. By applying multi-direction excitation to the tested pipeline,crack defects at more angles can be effectively detected,and the strongest set of signals is selected to solve the crack depth. Simulation and experiments show that the proposed MDFSM significantly improves the accuracy of detecting crack depth.

Key words: defect detection, metal pipeline, corrosion, crack, MDFSM, excitation current