Issue link: https://geospatial.trimble.com/en/resources/i/1415432
32 Spring 2019 height and for lengthy periods of time. In the case of internal tank inspections, personnel are also exposed to confi ned, hot, low visibility environments. As well as safety issues, inspections using these techniques usually take weeks, if not months, which leads to escalating costs. Across the industry, there is an ongoing drive to develop and apply new technologies to counter these problems. One such technology which has signifi cantly challenged the norm in recent years has been unmanned aerial vehicles (UAVs), more commonly known as drones. First internal tank inspection Cyberhawk has been using drones to inspect high, hazardous and diffi cult-to-access locations for more than a decade. In 2015, the company partnered with Maersk Oil (since acquired by Total) to conduct an internal tank inspection onboard the Gryphon floating production storage and offloading (FPSO) vessel. The inspection was completed in just one day – a major time reduction compared with the traditional rope access inspection, which would typically take 3 – 4 days. This project also highlighted how a drone could be used to conduct a safe, first audit of a tank and from there, any tactile inspection, repair or maintenance required could be focused into priority areas. The successful completion of this workscope meant a full tank inspection service could be introduced to the marketplace. Since then, multiple projects have been completed around the world in the upstream and downstream oil and gas and chemical sectors. What is involved in the inspection process? A two man team is typically mobilised, including a highly experienced drone pilot with hundreds (if not thousands) of hours of fl ight experience and an industry qualifi ed inspection engineer. This means that the pilot can focus on fl ying the drone while the inspection engineer can ensure that relevant visual data from the correct areas is captured. The latter is an important factor in providing the end client with engineering analysis, reporting outcomes and evidence that can be used for further planning and decision-making. Hardware developments were also a key factor in enabling internal tank inspection to become possible. For the external surface of tanks, a multi-rotor drone, designed for outdoor use, is typically used. However, for the tank's internal surface, a more robust, collision resistant drone is required in order to get into tight spaces and obtain detailed, close-up imagery. The introduction of such technology signifi cantly advanced how inspection in confi ned spaces is conducted (Figure 1). Tank inspection case study Following the introduction of the tank inspection service, Cyberhawk was tasked with a tank inspection project for a leading chemical manufacturer in North Teesside, UK. The workscope required an examination of the quality of the welds for the entire internal surface of an oil storage tank. This type of inspection would usually be conducted by rope access technicians who are suspended on ropes to inspect the internal structure. However, drones were selected as the preferred method of inspection for this project, primarily to reduce the safety risks posed to personnel working at height and in a confi ned space. With the added challenges of limited GPS signal inside the tank and dark conditions, the pilots had to work with an extremely high level of precision during the inspection to ensure a successful end result. The company successfully completed the workscope, delivering high resolution images which enabled the client to understand any defects present within the tank. The client reported that the project was carried out within budget and with signifi cant time savings, along with other positive feedback. Figure 2. Water storage tank. Figure 1. Collision resistant drone.