Ultrasonic Pipe Inspection with Conventional Transducers or Phased-Arrays? A Comparison Based on POD-Analysis Can Help

摘要

For automated online inspection systems used in industrial applications the inspection speed is one of the major parameters to focus on. Phased-array applications, compared to conventional transducer arrangements, are quite promising, because it is possible to substitute the information obtained via a set of different incidence angles by one sector scan. However, possible advantages in view of inspection time obtained by using more recent inspection techniques have to be crosschecked with regard to the performance of these techniques to detect certain types of defects and defect sizes, respectively. In this contribution, the results of a POD-analysis comparing conventional transducer arrangement versus a phased-array set-up will be presented. For the experimental part, a test pipe (ferritic steel) with a series of artificial defects with varying dimensions has been prepared. Ultrasonic data has been recorded with an automated scanning system for both applications, conventional and phased-array. The maximum indication amplitudes are used to calculate the Probability of Detection (POD) via an "a versus a"-analysis. This paper provides examples of the POD-calculations, where not only the "mh1823"-software according to MIL-HDBK-1823 has been used, but also POD evaluation software specifically developed at Fraunhofer ITWM. The results for both ultrasonic techniques are compared and are discussed with regard to the practical industrial application.