Interferometric synthetic aperture sonar in pipeline inspection

Accurate and reliable inspection of subsea pipelines traditionally requires the use of multiple sensors, which again have different requirements for range and geometry. This makes pipeline inspection a time consuming and costly process. The use of high resolution synthetic aperture sonar (SAS) can potentially change this substantially. Current state of the art interferometric SAS systems offer very high resolution imagery and bathymetry over a very wide swath. Mounted on an autonomous underwater vehicle (AUV), such a system can provide highly detailed data sets of a pipeline with just one or two passes - either fully autonomously, or with operator supervision as desired. In June 2009, a Kongsberg Maritime HUGIN 1000-MR AUV equipped with a HISAS 1030 interferometric SAS performed such a pipeline inspection mission in Western Norway. The paper will show examples of the data recorded during the above mission.