L51523 Modeling Ultrasonic Transducer Performance

Although automated ultrasonic inspection systems show considerable promise for pipeline weld inspection, they are used infrequently because difficulties with sensitivity, weld zone coverage, and the discrimination of imperfections from weld features lead to missed defects and false calls (mistaking weld geometry for defects). The present standards for pipeline construction require radiography for detection of girth weld defects. Radiography has inherent limitations for detection and sizing of serious planar defects; therefore, attention is turning to ultrasonic testing, which has advantages for detecting and sizing these defects. The ultimate objective of this work is to produce guidelines for the design of ultrasonic procedures that reliably and efficiently detect serious defects in pipeline girth welds without producing false calls. This is the final report for a contract which assesses the ability of EWE, an existing AECL computer model, to accurately simulate ultrasonic response from defects typically found in pipeline girth welds by modeling situations commonly found in pipelines and comparing modeled results with equivalent laboratory experiments. The main goal of this work is to determine if EWE can help improve the accuracy and reliability of ultrasonic testing of pipeline girth welds by answering the following questions: Are numerical A-scans in pulse echo mode accurate predictions of experimental A-scans? Are scattered waves predicted by EWE confirmed experimentally? Is EWE a useful tool for designing effective ultrasonic procedures?