This paper describes original ultrasonic testing(UT) technologies
developed by JFE R&D and JFE Steel in non-destructive inspection(NDI) systems
that assure the quality of JFE Steelﾕs steel pipes. High-speed digital-signal-processing
techniques of synchronous averaging and chirp-pulse compression have been developed
to improve the signal-to-noise ratio and been installed in ultrasonic flaw
detectors at welding steel-pipe miles. To improve detectability of flaws located
at the center of wall thickness of the weld, a normal-incident-beam technique
for UOE steel pipe and a multi-probe technique for ERW steel pipe have been
developed. The analytical technique of ultrasonic field and ultrasonic-wave
propagation is applied as a basis of the technical development.
