A riser forms the connection between the top side of an off-shore platform and a pipeline on the sea-bed. Such pipeline systems may be equipped with launch and receive facilities for cleaning and general intelligent pigging of the entire pipeline. The riser may be of different material or of heavier wall thickness, making self contained intelligent pigging of the
riser difficult, less effective or cost prohibitive. Today, offshore operators are strongly committed to protect the environment and pigging and riser inspection will assist in determining the condition of the installation and the riser in particular. In this description a new approach for a detailed ultrasonic inspection of the risers only is explained, based on the application of a compact umbilical (cable, tether) operated tool. This requires that the riser is bled down and liquid tilled. The inspection tool
provides on-line presentation of results for immediate evaluation. The system uses straight beam ultrasonic sensors for general corrosion survey in the pipe material and a novel ToFD (“Time of Flight Diffraction”) technique for additional inspection of the circumferential weld area.
Keywords: offshore, risers, environment, inspection, ultrasonic, pigging, cable tools, corrosion, condition monitoring, evaluation, ToFD.