A drone has successfully inspected a 19.4-metre high oil tank on board the Floating Production, Storage and Offloading vessel (FPSO) Petrojarl Varg as part of a test project. The video shot by the drone was interpreted in real-time by an algorithm to detect cracks in the structure.

The test (see video below) is the latest step in a technology qualification process by Scout Drone Inspection and classification society DNV GL. The autonomous drone system is to overcome the common challenges of tank inspections.

For the customer, costs can run into hundreds of thousands of dollars as the tank is taken out of service for days to ventilate and construct scaffolding. The tanks are also tough work environments, with surveyors often having to climb or raft into hard to reach corners. Using a drone in combination with an algorithm to gather and analyse video footage can significantly reduce survey times and staging costs, while at the same time improving surveyor safety.

‘We’ve been working with drone surveys since 2015,’ says Geir Fuglerud, Director of Offshore Classification at DNV GL – Maritime. ‘This latest test showcases the next step in automation, using artificial intelligence (AI) to analyse live video. As class we are always working to take advantage of advances in technology to make our surveys more efficient and safer for surveyors, delivering the same quality while minimising our operational downtime for our customers.’

LiDAR and live stream

The drone, developed by Scout Drone Inspection, uses LiDAR to navigate inside the tank as GPS-reception is not available in the enclosed space. A LiDAR creates a 3D map of the tank and all images and video is accurately geo-tagged with position data. During the test, the drone was controlled by a pilot using the drone’s flight assistance functions, but as the technology matures, it will be able to navigate more and more autonomously. DNV GL has been developing AI to interpret the video to spot any cracks and eventually, the camera and algorithm will be able to detect anomalies below the surface such as corrosion and structural deformations.

‘This is another important step towards autonomous drone inspections,’ adds Nicolai Husteli, CEO of Scout Drone Inspection. ‘Up until now the process has been completely analogue, but technology can address the urgent need to make the process more efficient and safer.’

Altera Infrastructure hosted the test on the Petrojarl Varg as part of its drive to improve safety and efficiency through innovative technology. The video was streamed live via Scout Drone Inspection’s cloud-system back to Altera Infrastructure’s headquarters in Trondheim, where the footage was monitored by engineers. DNV GL can also simultaneously watch the footage, opening up the possibility for stakeholders to work together from different locations.