New underwater digital radiography inspection system
18/10/2010
TWI, together with its project partners, has recently completed an EC collaboration funded FP6 project called FlexiRiserTest (COOP-CT-2006-032680).The work undertaken in this 2.5 year project has resulted in the development of a new prototype inspection system for the inspection of flexible risers. Existing radiography-based inspection of underwater structures uses film or phosphor imaging plates. These methods are time consuming because in between each exposure to the radiation source both film and phosphor plates have to be returned to the surface for development and processing. It is believed that it is the first time that a digital flat-panel detector has been used for underwater radiography inspection. The application of a marinised digital detector allows for rapid acquisition of radiographic images of the riser, and the results can be instantly relayed via an umbilical to a host computer located topside.
A robot crawler has been developed for deployment of the radiography-based inspection technique. The robot is capable of crawling along the external surface of the flexible riser, and is also able to rotate 360° about the riser axis so that the riser can be completely imaged. The inspection technology has been tested to an equivalent water depth of 20 metres. The project partners are confident that much greater depths (>100 m) are possible with further development and funding. The marinised detector technology is deployable now and can be used in underwater inspection solutions for TWI member companies.
Future work includes more underwater trials including sea trials and further development to achieve deployment at greater depths. TWI is currently seeking sponsors for sea trials. For further information contact ian.nicholson@twi.co.uk or visit the website www.flexirisertest.com
