'Ultrasonic Phased Arrays for Pipeline Girth Weld Inspections'

摘要

Mechanized ultrasonics is rapidly replacing radiography worldwide for gas pipeline girth weld inspections. Compared with radiography, mechanized ultrasonics is more reliable, faster, has better detectability for critical Lack of Fusion defects, and poses no safety hazard. Phased arrays present major improvements over conventional ultrasonics, particularly for offshore use. Probe pans are lighter and smaller, permitting less cutback; scans are quicker due to the smaller probe pan; phased arrays are considerably more flexible for changes in pipe dimensions or weld profiles, and for different scan patterns; phased arrays potentially can compensate for variations in pipe wall thickness. This paper describes the evaluations of an ultrasonic phased array system for girth weld inspections, using standard ASTM E-1961 Mechanized Ultrasonics calibration blocks. Phased arrays detected all known defects, and gave similar results to conventional mechanized ultrasonics. The paper will describe the latest phased array UT results, plus new developments like automated set-ups and improved imaging using an increased number of zones. A brief comparison of E-1961 and the recent API 1104 19th Edition codes will be made.