Quantitative Ultrasonic Testing of Pressurized Components Using Sampling Phased Array

Ultrasonic testing and evaluation procedures typically depend on reference reflectors to establish detection sensitivity and evaluation of test data. Rules and regulations governing safety-related components emphasize on test procedures that assure the detectability of discontinuities at all over the component and oriented in any arbitrary direction. Existing procedures, however, do not provide information for a quantitative presentation of type and size of the detected discontinuities. To size the defects it requires additional measurements and analysis, involving complex inspection procedures and highly qualified expert personnel, are required. Furthermore, critical flaws evaluated with fracture-mechanics analysis appear much larger than comparable detectable reference reflectors. For ultrasonic testing results to become relevant input for the fracture-mechanics analysis, the ultrasonic test data must deliver high-quality flaw images that are quantifiable. For industry to use such an approach these test techniques and procedures should be able to perform inspections at normal inspection speeds and without the need for specialized or extraordinary inspection resources. To satisfy the condition to detect defects oriented in any direction requires the inspection to be done with all beam angles (from -90° to +90°), with high sensitivity and resolution. Fraunhofer Institute Nondestructive Testing has developed sampling phased array technique to overcome the existing limitations of ultrasonic imaging. Using welladapted reconstruction algorithms and highly efficient integrated computer architectures the Sampling Phased Array technique is capable of producing quantifiable flaw images for various industrial applications. A special adaptation of this technique with virtually controlled aperture high resolution focusing is possible at long sound paths. This paper presents the results of the applications where this technique is used on industrial components, such as heavy wall components, piping system weld joins and turbine shafts.