Groove dimensioning using remote field eddy current inspection

The remote field eddy current technique is used for dimensioning the groove s that may occur in the ferromagnetic pipes. We propose a method to estimat e the depth and the length of corrosion grooves from measurement of a pick- up coil signal phase at different positions close to the defect. Groove dim ensioning requires the knowledge of the physical relation between measureme nts and defect dimensions; therefore finite-element calculations are perfor med to design parametric algebraic functions for modeling the physical phen omena. Different models are possible; the choice of this algebraic function is discussed from identification criteria. By means of new measurement for malism and two previously defined measurement relations, estimates of groov e sizes may be given. In the first approach, algebraic function parameters and groove dimensions are linked through a polynomial function; this approa ch is proved to be better than a second one which tries to take advantage o f more physical considerations.