High-energy X-ray Computed Tomography/Digital Radiography (CT/DR) technologies are being investigated in order to develop a significantly enhanced non-destructive examination (NDE) capability for in-service inspection of flexible risers. Statoil Research Center, in concert with U.S. and European manufacturers, have studied advanced industrial high-energy X-ray, CT/DR, and robotics systems for potential use in offshore oil & gas production facilities. The objective is to adapt these technologies for in-service NDE of flexible risers and end-fittings on FPSO vessels and TLP structures, as well as other configurations. Both topside and sub-sea versions of the device are envisioned. The device will use a miniature electron linear accelerator as the X-ray source. The CT/DR detector consists of an array of photodiodes and signal amplifiers, an advanced computer workstation, and integral robotics used to rotate and translate both the X-ray source and detector array. For topside applications, an external radiation shielding unit will be installed around the system. For sub-sea applications, the X-ray source, detector array and integral robotics will be mounted on a ‘clamping-walking’ robot that attaches to the outside of the flexible riser. The tool is to be installed on the riser by a large Remote Operated Vehicle (ROV), with control logic and power supply provided by cables embedded in the Tether Management System (TMS). Image data captured and transmitted to the workstation are processed, stored and displayed digitally. Reconstructed CT/DR X-ray images generated offshore can be rendered in 2D or 3D display, and transmitted to remote terminals anywhere in the world.

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