Customized Ultrasonic Systems for Gas Pipeline Girth Weld Inspections

Abstract

Gas pipeline ultrasonic inspection girth weld systems have been well established for typical Canadian conditions, primarily through the efforts of TCPL and NOVA. However, the specific weld profiles, wall thickness, environment and operating conditions found in Canada do not necessarily represent girth weld inspections elsewhere. This paper describes some different inspection conditions, and some of the possible solutions, which may or may not have been implemented to date. For example, the extreme Canadian weather may require heating transducer wedges, or using dummy wedges to measure temperature. Sandy or salty conditions may require different designs and materials. Different weld profiles will require different ultrasonic set-ups, as will different inspection specifications. For flexibility, it is possible to design expandable inspection heads with replaceable probe modules, and to include extra ultrasonic transducers for TOFD or additional scans. Tight time constraints can lead to quick-release levers for speedy head changes, as well as modular, replaceable components. Since the operator is critical in the inspection, a number of software additions can be added to speed inspection, interpretation and set-up. For example, defect locations can be automatically displayed on the weld profile to aid interpretation. A table of defects can be shown so the operator can click on a selected defect to automatically display the appropriate scan region. Defects can be analyzed automatically by length and amplitude to determine accept/reject. Calibration set-up for a particular transducer can be recalled simply by clicking on the appropriate zone in the weld display. Automated recording and acceptance of calibration scans can be performed.