BACKING MATERIAL CONFIRMATION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a backing material confirmation method capable of confirming whether a backing material is present on a rear surface of a weld zone and further confirming an end face position of the backing material even if the rear surface of the weld zone is unable to be visually recognized.SOLUTION: Provided is a backing material confirmation method using an ultrasonic probe 105 arranged on a front surface of a steel plate 102 of a plate 101, including: detecting whether a backing material 104 is present on a rear surface of a weld zone 103 by determining whether an echo is detected; and acquiring an end face position of the backing material 104 on the basis of an echo propagation distance.