Difficult to Pig and to Inspect Offshore Pipes
Proceedings Publication Date
This paper presents the advanced subsea inspection technology and tools that have been developed in response to market demands for the inspection of subsea pipelines which are difficult to inspect. Very often, a single inspection technology is not able to achieve all the required condition information for a valuable asset integrity assessment. Different NDT technologies are sometimes complementary and capable of providing a larger extent of condition data when used in combination. As a result, the MEC-Combi Crawler has been developed to enable the inspection of subsea pipelines and structures. A versatile inspection tool, it combines the advantageous SLOFEC technique already proven in the field to be suitable for splash zone and subsea inspections with other supporting inspection techniques like Ultrasonic, Pulsed Eddy Current and camera system to provide comprehensive inspection data within a single inspection deployment. Deployed by ROV or divers and powered by a hydraulic drive unit, the MEC-Combi Crawler is able to move along subsea pipelines or crawl up subsea structures at depth of up to 400m while performing the inspection. Experience from a subsea pipeline inspection job in western Australia will be presented. The patented MEC-FITTM technology has been developed to provide a reliable and technically advanced inspection solution for general and flexible risers as inspection techniques available in the market are able to inspect only the near side layers for wire disruptions while the far side layers remain uninspected. The MEC-FITTM technique combines the direct magnetic field lines with eddy current field lines to allow a deeper penetration into the ferrite steel material for the detection of localised material defects such as cracks and corrosion beneath the riser coating at the single wire or wire areas. An electromagnetic technique, it also does not require annulus flooding. Field experience from a flexible riser inspection job performed in the North Sea will be presented.