Submersible Assisted Cathodic Protection Surveys Of Subsea Pipelines

Video inspection of offshore pipelines immediately following installation using either manned or unmanned submersibles is becoming an increasingly common practice, particularly as pipelines are installed in deeper and deeper water. A method has been developed and put into practice during the last year to perform detailed cathodic protection surveys of offshore pipelines in conjunction with the post lay video inspection. The information provided by this survey includes a continuous pipe-to-electrolyte potential profile, location and comparative output of bracelet anodes, detection of poorly or improperly coated field joints, and detection of coating flaws. This information is useful as baseline data for future comparison and as a check on the installation of the pipelines cathodic protection and coating systems. Description of the basic theory, procedures and apparatus, and survey results will be given. Data recorded during surveys using both manned and unmanned submersibles will be presented and current and future applications will be discussed.