Conventional non-destructive techniques for inspection of weld in pipelines require
significant test time and high cost. In order to overcome these drawbacks in conventional NDT
techniques, various techniques using ultrasonic guided waves have been developed and applied to the
pipeline inspection. Recently, a fast calculation technique for guided wave propagation using a
semi-analytical finite element method (SAFEM), PIPE WAVE ver.1.0, has been developed by T.
Takahiro et al [1]. In this paper, the calculation of torsional mode propagation in a pipe using PIPE
WAVE ver. 1.0 is introduced as a preliminary study and the application of the torsional mode of
ultrasonic guided waves to long range pipe inspection is presented.. The characteristics and setup of a
long range guided wave inspection system and experimental results in pipes of various diameters are
introduced. The experimental results in mock-up pipes with cluster type detects show that the limit of
detectable wall thickness reduction with this guided wave system is 2~3% in the pipe cross section
area and the wall thickness reduction of 5% in cross section area can be detected when actual
detection level is used. Therefore, the applicability of the ultrasonic guided wave technique to long
range pipeline inspection for wall thickness reduction is verified.
