A Novel Electrical Based Breach Detection System for Flexible Pipe

An outer shield breach is the most common form of damage that can occur to a subsea flexible pipe during both installation and operation. Definitive and accurate detection and location of such damage is imperative in triggering the appropriate repair response. The overall aim is to minimise corrosion damage to the carbon steel strength elements in the pipe annulus, which occurs from the resulting ingress of seawater. GE Oil & Gas, in collaboration with Photon Fire Ltd have developed a new method of detecting seawater in a subsea flexible pipe annulus. This paper describes a novel breach detection system developed to monitor pipes using very low energy electrical signals appropriate for use in hazardous areas. The technique provides an enduring record of the occurrence of a breach and the extent of the subsequent flooding. A brief outline of the development programme is presented. The work involved determining the sensing technique used, development of appropriate electronic instrumentation, the optimised method for installing the sensor into the riser, and bespoke connection to the instrumentation. A prototype system, approved for use in Hazardous Area ATEX zone zero has been implemented on midscale pipe samples and the transient and steady state ‘scans’ of the pipe have been investigated. A summary of the test results and a proposed testing regime is presented. Results show that using this technique can accurately determine that a breach has occurred in the wall of the riser and the extent of the flooding.