PURPOSE: To identify 5% or less flaw depth of the pipe wall thickness of an electrical resistance welded part in a product such as the pipe and 10% or more flaw depth.
CONSTITUTION: A device for identifying approximately 5% or less and approximately 10 % or more depth of the pipe wall thickness of the electrical resistance welded part of a product such as a pipe detects reflected ultrasonic wave surface waves and shear waves by generating ultrasonic wave surface waves using at least two first and second electromagnetic acoustic transducers and propagating the surface waves along the surface of a welded line and generating ultrasonic shear waves by a second electromagnetic acoustic transducer and propagating the shear waves through a welded line. The flaw depth of the product is identified by using the amplitude of the detected surface wave and shear wave signals and cooperating with a logic circuit means 22. The logic circuit means 22 operates an alarm 24 for a flaw depth that is 10% or more but does not operate it for a flaw depth that is 5% or less, thus avoiding the unneeded elimination of a fine flaw and hence avoiding the waste of time and material due to the elimination of the product with a fine flaw as a nonconforming article.
JIYON EICHI FUROORA
POORU JIEI RATEIMAA
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