Patent ID: 11965856
Assignee: NIPPON STEEL CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  B | IPC B  G

Claim 9:
10. The method for detecting a metal residue present in an electric-resistance-welded steel pipe according to claim 1,
wherein a plurality of the detecting coils is disposed in the longitudinal direction of the electric-resistance-welded steel pipe, and
the second step includes
a step of averaging the output signals of the plurality of detecting coils output at the same time to compute a first signal,
a step of subtracting the first signal from the output signals of the plurality of detecting coils output at the same time to compute second signals respectively corresponding to the plurality of detecting coils, and
a step of detecting the metal residue present in the electric-resistance-welded steel pipe on the basis of at least any one of the plurality of second signals.