Current 'State of the Art' Piping Examination Technology
S. Walker, J.F. L. Landrum, D.E. MacDonald, EPRI NDE Centre, Charlotte, USA
ABSTRACT
Improvements are currently being made in non-destructive evaluation (NDE) equipment, which have advanced the state of the art of piping examinations. Phased array ultrasonic examination technology has an increasing potential for utility applications with the availability of high-performance piezocomposite array probes and more affordable industrial array control systems. The demand for accuracy and efficiency of inspection techniques can be met by inspection techniques that use ultrasonic phased arrays where a single array probe can be controlled electronically to generate ultrasonic beams of many different angles and to focus at many different points in the inspected component. Likewise, electromagnetic acoustic transducer (EMAT) systems are becoming less expensive and have the potential to save examination costs while improving flaw discrimination capabilities. EMAT systems are being developed which produce horizontally polarised shear (SH) waves which are less affected by austenitic weld metal than are conventionally used vertically polarised shear waves. EMAT-produced SH waves have been used to successfully detect intergranular stress corrosion cracking (IGSCC) through austenitic piping welds and with fewer scan lines than are conventionally used, allowing single-sided examinations and reducing examination time. Lessons have also been learned concerning ultrasonic examination of dissimilar metal welds and welds in cast stainless steel. These difficult examination challenges require examiner familiarity with the materials and crack characteristics which have been observed in similar configurations.
Publication Source: First International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurised Components , 20 - 22 October 1998, Amsterdam, Netherlands. Held by the Joint Research Centre of the European Commission. Publisher:Woodhead Publishing Limited
NDTnet
