INSPECTION METHOD, INSPECTION DEVICE, TEMPERING STATE INSPECTION METHOD AND APPARATUS THEREFOR

摘要

PROBLEM TO BE SOLVED: To inspect the tempering states of a plurality of steel pipes flowing along a manufacturing line for tempering treatment over the total number of those steel pipes on-line with high accuracy in a nondestructive manner. SOLUTION: In the inspection method for inspecting the tempering state of the steel pipe 2, the steel pipe 2 is passed through the coil 4 constituting an oscillator 14 and a change in the oscillation frequency outputted from the oscillator 14 is measured to inspect the tempering state of the steel pipe 2.