Pipeline Girth Weld Inspections Using Ultrasonic Phased Arrays

Abstract

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 multiprobe ultrasonics, both for onshore and 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 have great potential for the future, such as compensating for variations in pipe wall thickness or temperature. This paper describes the evaluation of the PipeWIZARD ultrasonic phased array system for girth weld inspections, using standard ASTM E-1961 Mechanized Ultrasonics set-ups. Some typical results will be shown. The paper will describe the latest phased array UT results, plus 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, plus a summary of approvals and track record to date.