Flying to safety

Confined space entry is one of the most dangerous types of work that inspectors perform. According to the Bureau of Labor Statistics, from 2011 – 2018 a total of 1030 people died due to occupational injuries involving confined spaces.1 These numbers are only for the US – the global count is likely much higher. In addition to the dangers of work inside confined spaces, inspectors who carry out tank inspections often face the additional hazards of working on ropes or at height on scaffolding while within a confined space.

Despite these dangers, confined space entry has historically been a necessary risk that inspectors assume for conducting tank inspections. But in the last few years, drones made specifically for operating in confined spaces are helping to change this reality.

Generally called indoor drones, these drones are protected by a cage and come with collision-tolerant features that allow them to bump and collide while operating in confined, cluttered environments, and continue flying unharmed.2 Advances are being made in this field all the time.

Flyability has recently developed a patented technology that enables its indoor drone to right itself after being turned upside down by a collision.

How indoor drones make tank inspections safer

A reliable indoor drone allows inspectors to collect visual or other data inside a tank remotely. The drone serves as a proxy for the inspector, flying into the confined space,

Zacc Dukowitz, Flyability, USA,

explains how drones are helping to improve safety for tank inspections.

collecting the data needed for the inspection, and then flying out, all while the inspector remains safely outside of the tank.

Here’s how a drone inspection inside a tank works: n Beforehand inspectors make a plan, identifying the outputs they need for their reporting and the data they need to collect. n On the day, inspectors plan a flight path that allows them to collect all of the visual data they need to meet the requirements of the inspection. Often, multiple flights may be required to get all of the data needed. n During the flight, inspectors identify potential defects, such as a crack in a weld, and collect as much visual data as they need to satisfy the requirements of the inspection. n After collecting the data (typically photos and videos), inspectors review it to identify any potential defects that need to be included in their reporting.

The video footage that the drone collects acts as a historic record of the conditions inside the tank, allowing all the stakeholders involved in the maintenance process to see the same data and monitor changes within the tank over time.

Tank inspection by drone – three case

studies

This article will provide three examples of ways that indoor drones have been used by inspectors to improve safety in their work for inspecting ballast tanks on a drilling rig, cargo tanks on an FPSO, and an oil storage tank.

Drilling rig ballast tank inspection

In Brazil, administrators at a shipyard in the city of Angra dos Reis were looking for a new way to inspect their drilling rigs.3 They had previously carried out inspections by sending inspectors into their columns and ballast tanks via rope access. This approach was dangerous and expensive, since it extended the downtime in which the rig could not be used to drill.

To improve safety and reduce downtimes, shipyard administrators decided to test using an indoor drone for a tank inspection, and hired drone inspection service provider DR1 Group. The tests were a success, and DR1 Group was able to demonstrate that a drone could be used to collect visual data inside the ballast tank, reducing the danger to the inspector from confined space entry.

Figure 1. The Elios 3, an indoor drone made by Flyability.

Figure 2. An indoor drone flies into a ballast tank on a drilling rig to collect visual inspection data. Credit: DR1 Group.

Figure 3. An indoor drone inside a cargo tank on an FPSO. Credit: Texo. Benefits:

n Safety: no confined space entry or work on ropes was required for the inspection. n Savings: 60% cost reduction by using the indoor drone instead of a traditional approach. n Reduced downtime: an 80% downtime reduction was achieved by using the indoor drone instead of a traditional approach, cutting the total time for the inspection from five days to just one.

FPSO cargo tank inspection

A typical cargo tank inspection on an FPSO takes about two weeks, and often requires the use of scaffolding or rope access to allow inspectors to work at height.

The lost oil production caused by the two-week downtime presents a significant loss of revenue for the oil company. An added cost for the inspection is scaffolding, which can be expensive and time consuming to put up and take down.

To improve the process, inspectors at Texo performed a test cargo tank inspection with an indoor drone.4 To create the safest, most organised approach for the inspection, Texo partnered with DNV. Working with DNV and the FPSO operator, a new step-by-step process was created for how to perform an FPSO cargo tank inspection by drone.

Atmosphere explosible (ATEX) considerations were an important part of the process, given the potentially explosive environment in which the inspection would take place. To address ATEX issues, inspectors worked with the FPSO owners to undertake extensive hazard identification and comprehensive risk assessments, ensuring that the drone operations could be safely undertaken. The following steps were taken: n First, all isolations were managed as per the operator’s standard procedures in order to eliminate any sudden combustible medium entering the tank during the survey. n Next, the tanks were thoroughly cleaned to ensure that no manned entry would be required. n Finally, the tank underwent active venting.

All the operations were conducted with gas monitoring prior to every launch. All of this was conducted under a Cat 2 Hot Works permit, with the appropriate risk assessment taken according to the requirements of the permit.

Benefits:

n Safety: using an indoor drone allowed inspectors to collect visual data inside the cargo tank remotely, which meant that no one had to perform confined space entry, use rope access, or work at height on scaffolding to collect inspection data. n Speed: using an indoor drone reduced the time needed for the inspection from 14 days to just 4 days.

n Reduced work hours and savings: using an indoor drone reduced the number of people needed for the inspection from four to two. This meant significant savings, both in terms of labour costs and in terms of space needed for housing on the FPSO.

Bulk crude oil storage tank inspection

In an effort to improve its maintenance processes, Pertamina hired Halo Robotics, a drone technology company based in Jakarta, Indonesia, to help with a massive maintenance project at one of its oil refineries in Balongan, Indonesia, a refinery with a capacity of 125 barrels per stream day.5

The specific asset at the Balongan refinery that needed to be overhauled was a huge bulk crude oil storage tank. The tank shares features that are identical to those found in API 650 tanks, which are used for bulk crude oil and gasoline storage throughout the world, hypothetically making the results of – and methods used for – the maintenance project applicable to any refinery that uses API 650 tanks.

Pertamina’s requirements for this maintenance project were: n To update the tank’s original drawings from 1972 with as-built schematics and blueprints. n To systematically inspect the interior of the tank to determine engineering, procurement, and construction (EPC) requirements. n To mitigate risk for inspection personnel by reducing the need for rope access and manned entry into tanks throughout the refinery, using this tank as a test case. n To improve the overall efficiency of EPC maintenance processes, including evaluation, planning, and project execution.

The inspection was completed successfully with the indoor drone. It took five days to complete the inspection, with inspectors conducting approximately 20 flights in that time.

Figure 4. Inspectors from Halo Robotics preparing to fly a drone inside a crude oil storage tank. Credit: Halo Robotics.

Benefits:

n Safety: using an indoor drone to collect visual data inside the oil storage tank removed the need for manned entry via rope access and scaffolding, significantly improving safety for the inspection.

Figure 5. A drone pilot looks at a 3D live map created by an indoor drone.

n Return on investment (ROI): costly, time-consuming inconsistencies between asset owners and EPC contractors were reduced with data collected by the indoor drone.

Savings were also realised from reduced downtimes and not needing to build costly scaffolding. n Efficiency for the oil storage tank inspection was significantly improved using an indoor drone, with processes created that can enable systematic, repeatable inspections of ageing assets for long-term analysis in the future.

The future of tank inspections with drones

In some instances, inspectors using indoor drones for tank inspections must still enter the tank to ensure that the drone is getting full coverage. This means that inspectors still face the hazards of confined space entry in some instances. But advances in drone technology are removing even this limited need for confined space entry.

By using LiDAR data and SLAM (simultaneous localisation and mapping) technology, new indoor drones can create a 3D map of the environment in which they are flying as they fly.6 These 3D live maps provide inspectors with enhanced situational awareness of the environment in which they are operating, and can help ensure that they are getting full coverage without the need for them to enter the environment at all.

As drone technology continues to develop, the safety benefits it provides for those working in oil and gas, and specifically in tank inspections, will only continue to grow.

References

1. 'Fact Sheet - Fatal occupational injuries involving confined spaces - July 2020', US Bureau of Labor Statistics, https://www.bls.gov/iif/ oshwc/cfoi/confined-spaces-2011-18.htm 2. 'The best indoor drones of 2022 (new guide)', https://www.flyability. com/indoor-drone 3. 'Elios 2 cuts downtime by 80% in drilling rig ballast tank inspection', https://www.flyability.com/casestudies/drilling-rig-ballast-tankinspection 4. 'Texo pioneers remote inspection method in FPSO cargo tanks with the Elios 2', https://www.flyability.com/casestudies/fpso-cargo-tankinspection 5. 'Oil storage tank inspection sees improved safety, cost, and efficiency with the Elios 2', https://www.flyability.com/casestudies/oil-stroagetank-drone-inspection 6. 'What is simultaneous localization and mapping (SLAM)?', https:// www.flyability.com/simultaneous-localization-and-mapping

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