|Live asset inspection with remotely operated aerial vehicles (ROAVs) offers benefits not delivered by traditional methods
Maximizing uptime is a major concern for utilities all over the world. Accordingly, there is an ongoing requirement to carry out close visual inspections of plants and equipment as part of a planned maintenance schedule.
Additionally, there is a continual desire to improve the health and safety performance and this is especially prominent in potentially dangerous locations found in the utility sector.
Power stations and network operators traditionally use rope access techniques or scaffolding to access high or difficult-to-reach structures such as chimneys, cooling towers and transmission towers. These ‘traditional’ access methods have associated drawbacks, including the requirement to shut down the asset if it is live or hot. This provides potentially huge commercial and health and safety disadvantages for the power station or network operators.
In addition, rope access and scaffolding involve working at height. Falls from height are statistically the single biggest cause of workplace fatalities and account for as many as 31 per cent of all such fatalities in the UK, according to recent figures from the Health & Safety Executive.
Rope access inspection can be time-consuming, both in terms of crew setup and inspection duration. Scaffolding is an expensive option and may take weeks to erect. The third traditional inspection technique is the use of full-sized helicopters to inspect transmission towers. Although effective, there can be problems with low cloud cover, availability, disturbance to people and animals on the ground and significant costs involved.
Live asset inspection using remotely operated aerial vehicles (ROAV) addresses these problems and delivers further benefits not offered by traditional methods.
A safe alternative
This new method of inspecting live and difficult-to-access assets has been pioneered by Scottish inspection company Cyberhawk Innovations and combines ROAVs, highly skilled pilots and engineering experts to carry out close visual and thermal inspections. Using ROAVs for inspection requires flying close to the structure of interest and capturing hundreds of detailed photographs and high-definition video.
This data is then analyzed by inspection engineers and a comprehensive engineering report on asset condition is produced. This report enables fact-based asset maintenance decisions to be made by the owner.
The ROAV inspection method offers operators a safe and comprehensive alternative to traditional approaches. Live asset inspection using ROAVs can also enable the operator to avoid the significant costs associated with asset shutdown. Unplanned shutdowns can often be prevented by using ROAV inspection to accurately assess the defective asset in question, rather than shutting the asset down at the first sign of an issue.
Planned shutdowns can be made more efficient by using ROAV inspection to identify precisely the condition and exact specification of parts that need to be replaced – an important consideration in an industry where parts may have to be pre-manufactured. The miniature flying vehicles or ROAVs use high-definition video and high-definition still and thermal cameras to provide detailed information for inspection purposes.
The battery-powered ROAVs weigh less than 2 kg – about the weight of a large seagull – and are less than 1 metre in length. They are operated by a highly trained two-man crew which comprises a pilot and a qualified inspection engineer. A two-man crew is critical for safe industrial inspection using ROAVs.
The ROAV is flown from the ground by a pilot who remains within sight of it at all times. Typically the take-off and landing positions are close to the base of the structure being inspected. With the pilot’s attention focused solely on the operation of the ROAV, the inspection engineer is able to concentrate on controlling the camera payload.
This ensures the ROAV team is able to capture clear close visual inspection (CVI) images and produces a comprehensive and authoritative technical report that enables asset owners to make informed maintenance decisions.
With an experienced and qualified inspection engineer on every assignment and the presentation of an interim report before leaving the site, the customer is able to have a timely, peer-to-peer discussion about the condition of their asset.
Although ROAVs have certain automated features, safely piloting one in an industrial setting requires a high degree of pilot training and skill. These elements are required to enable them to accurately and consistently position the ROAV close to the asset and to ensure that they can respond safely to unexpected events, from a gust of wind to signal interference.
Cyberhawk refers to this as the ability to fly in full ‘manual’ mode and this is a cornerstone of its pilots’ training regime. Certain asset inspections, such as the underdeck of an offshore oil rig, require 100 per cent manual flying and, especially in this case, a high level of pilot skill is vital to safe operation.
Over the last four years, Cyberhawk has established the use of ROAVs for close visual and thermal inspection of structures across the energy industry, at power stations, wind farms, oil and gas sites and across electricity networks. Assignments have been completed in Europe, the Middle East and Asia for customers such as SSE, RWE Npower, Centrica, E.ON, Statoil, Shell, BP, Total, ExxonMobil and ConocoPhillips.
The first deployments of micro multi-rotor ROAVs were in the oil and gas industry at onshore refineries and processing plants in the UK in 2010. In 2011, Cyberhawk took its technology offshore in the UK’s North Sea.
Improving inspection regimes
The model of live inspection means that, for the first time, operators have an opportunity for a safe and cost- and time-efficient method to understand the condition of their assets before shutting down and without exposing personnel to the risk of working at height.
As a result of this inspection methodology being available, many electricity operators are now inspecting their assets on an annual basis as part of a planned inspection regime while others prefer to monitor on a monthly basis to track deterioration or known problems.
This can extend time between shutdowns by allowing informed decision-making based on an accurate record of asset condition. This is a technology that not only supports ongoing production but extends it wherever possible, based on real data and real assessments of asset integrity.
Even when a problem does occur at a site, with this new technology a shutdown may not always be required. Emergency inspections can be carried out to gain engineering certainty, often avoiding the need for an unplanned shutdown as a result of the images and analysis provided by the engineers on site.
Cyberhawk recently completed a close visual inspection using an ROAV to determine the external condition of two 170-metre chimney stacks at a power station. The purpose of the inspection was to quantify the current condition of the chimney by capturing high definition video footage and photographs of the entire asset.
Post-processing the visual data captured during the inspection allowed the creation of a highly accurate three-dimensional model of the structure. This was provided to the client as record of their asset, together with a bespoke database listing every defect, its type and accurate dimensions.
Additionally, thermal inspection of the elevated chimney ducting was completed. This provided analysis of the condition of the ducting and areas of refractory breakdown that could be addressed at the next shutdown.
By using ROAV technology, the need for steeplejacks was removed, resulting in a huge cost saving, quicker turnaround, a step improvement in safety and improved asset management information.
|Damaged transmission line
ROAV inspections are an extremely cost-effective way of determining the condition of not just structures at power stations but transmission towers for network operators. Cyberhawk has won a major contract to inspect 1000 electricity pylons for SSE’s (formerly Scottish and Southern Energy) transmission business. The six-figure contract will provide SSE with the detailed inspection reporting it requires to plan the maintenance of its electricity network. The ROAV inspection method delivers significant safety benefits by eliminating the working at height risks associated with traditional climbing inspections. It provides detailed inspection reporting that enables SSE to accurately assess tower condition and plan future spend on the transmission network.
The inspection information gathered by the ROAV is comparable with what SSE get from climbing the towers, but is more systematic and objective, with an image behind each part’s inspection rating.
Having the asset-condition data at their fingertips enables companies to optimally allocate their maintenance, repair and upgrade resources – and that means increased value to their customers in terms of service delivery.
ROAV inspection provides a high-quality photographic record of the condition of each tower together with accurate defect classification, which removes subjective opinions of the structural condition and provides evidence behind each inspection. In addition, it also provides a step improvement in safety by reducing working at height and provides dramatic cost savings by reducing outages to the power lines.
The ROAV inspection method has become an established alternative to inspection by full-sized helicopter as it offers a range of operational and safety benefits.
These include the ability to obtain inspection images from key angles that are not possible using a full-sized helicopter. For example, when inspecting an insulator disc, the engineer can dictate the angle of the image captured, thus giving the advantage of being able to detect corrosion underneath the discs.
This is also apparent with the inspection of shackles and U-bolts where shots can be taken at a level height, giving a clear view of the wear, as opposed to simply capturing images from above. ROAV inspection removes the dangers of full-sized manned aircraft operating at low levels close to structures, high voltage lines and people. It also means a much lower level of disturbance to neighbouring houses and livestock.
|Unmanned aerial vehicles (UAVs) can provide construction progress imagery such as this view of a substation
Technology for land survey
ROAV technology is not just about existing asset inspection: it can also deliver survey information more quickly and safely, and in much higher detail, than has been previously available.
Cyberhawk’s land survey department provides topographic surveys that are quicker to acquire and of higher resolution than those achieved by traditional survey methods. It has proven to be a transformational way of gathering survey data for transmission line routes and for substation planning and construction.
Carried out using unmanned aerial vehicles (UAVs), the information is highly beneficial for assessing potential site locations, designing site layouts, generating 3D visualizations, assessing site visibility, calculating earthworks volumes, monitoring construction progress and producing as-built records.
As well as the topographic data, high-resolution aerial photography are supplied. Oblique panoramic images taken from up to 120 metres above the ground give a unique overview and an understanding of a site’s scale and setting, while vertical photography is overlaid on elevation models to show topographic features and surface types. The photography resolution can be up to 2.5 cm/pixel, as opposed to off-the-shelf aerial imagery where the resolution can often be 12.5 cm/pixel at best.
A Cyberhawk land survey can cover more than 100 ha in a day and generate more than three million points of detail combined with high resolution orthophotos. In comparison, traditional survey methods using ground-based total station instruments or GPS may observe 1000 points of detail in a day.
The accuracy of the survey information derived by UAV is in the region of 100 mm vertically and 50 mm horizontally depending on the required resolution of the images and the number of ground control points.
Many sites and related infrastructure, particularly in the case of renewables, are often situated in hostile environments such as hilltops, moorlands, remote valleys, cliffs and tidal areas, so when a survey lasts for several weeks the exposure to risk at such sites can be significant. By contrast, UAV surveys provide cost savings together with huge safety benefits by reducing survey time and removing the risks to people, as only minimal site access is required by personnel. Safety is a paramount concern.
Just like operating a full-sized aircraft, UAV operators in the UK need to be approved and certified by the CAA (Civil Aviation Authority) and carry the appropriate insurances. Pilots need extensive training and qualifications to be able to safely and consistently operate a UAV.
Craig Roberts is chief executive of Cyberhawk Innovations
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