Long Range Guided Wave Testing- A Novel Tool for Rapid Screening of Piping for Corrosion

Corrosion in pipe work is a major problem. While most plants have reliable information on most equipment, the least data available is always with respect to their piping. Significant portions of plant piping and pipelines are insulated or buried and hence, even external corrosion cannot be readily observed. Ultrasonic guided waves in the pipe wall provide an attractive solution as the waves are excited from one location of the pipe and travel meters of distance, with the returning echoes indicating the presence of corrosion or other pipe features. The Wavemaker Pipe Screening System (WPSS) developed by Guided Ultrasonics Limited exploits this benefit of Ultrasonic Guided Waves and has been deployed successfully on a wide range of application for screening of pipes for corrosion. An offshore operator had got Escon to inspect several risers and tests were conducted on a mock-up sample prior to the commencement of field inspection. The initial focus was the assessment of the inaccessible region under the riser clamp. The inspection subsequently focused not only on the riser clamp region but at the whole length of the riser with several defects found at welds, supports, interfaces etc. This paper provides an overview of the technique, the methodology adopted to implement the tool at actual conditions offshore & other proven applications for the technique.