Pipeline Bonded Joints Assemble and Operation Health Monitoring with Embedded FBG Sensors

Off-shore oil and gas platforms present a harsh environment for their installed infrastructure, with pipelines that are both subjected to a corrosive atmosphere and transport aggressive chemicals being the most critical. These conditions have prompted the industry to substitute metallic pipelines for composite counterparts, often made of fiber reinforced plastics assembled with bonded joints. Various technologies have emerged in the recent years to assess the health of these composite pipelines. In particular, robust speckle metrology techniques such as shearography have produced very satisfactory results. However, these inspection techniques require specialized equipment and trained personnel to be flown to off-shore platforms, which can incur in non-trivial inspection costs. In this paper we propose and demonstrate a robust and cost-effective approach to monitor pipeline bonded joints during assembly and operation using fiber Bragg grating (FBG) sensors embedded into the joints’ adhesive layer. This has been achieved by instrumenting bonded joints between 4” nominal diameter industrial grade Chlorinated Polyvinyl Chloride (CPVC) pipes with 12 sensing fibers, each fiber contains 3 FBGs for a total of 36 strain measurement points. To validate this approach, we present and compare data collected from both structurally sound joints and joints with controlled defects for various situations, including joint and pipeline assemble and operation. Computed tomography has been used as the control technique to evaluate structural soundness of tested joints. This approach allows for informed decisions on when to perform targeted in-depth inspections based on both real-time and long-term feedback of the FBG sensor data, resulting on lower monitoring costs, a severe increase on monitoring uptime (up to full uptime), and increased operational security.