Confined spaces inspection in industrial assets: is drone a solution?

[ February 15th, 2018] The need to inspect confined spaces is present in virtually all industries. Patrick Thévoz explores the modern ways to perform confined space inspection and explains the role that drones will play in the coming years.


By: Patrick Thévoz

Confined-space.jpgThe need to inspect confined spaces is present in virtually all industries. Stricter regulations, HSE guidelines and ageing assets require increasingly frequent, more thorough and more complex inspections of elements such as silos, tanks, sewers, pipes, access shafts, chimneys, boilers, manholes or underground cable galleries.

Work in confined spaces typically carries the following risks:

  • Insufficient amount of oxygen for the worker to breathe, or the presence of asphyxiants
  • Presence of hazardous chemical or biological substances
  • Risk of fire or explosion
  • “Mechanical” hazards: moving parts of equipment, structural hazards, engulfment, entanglement, slips, falls, collapse or falling debris

These risks are mitigated at a high cost in terms of protective equipment, staging, administrative time to apply and process entry permits, and very often the need for a worker to stand by the opening to ensure it remains open as one of its colleagues is working inside.

Man-entering-confined-space-with-breathing-apartus.jpgFinally, the downtime of the infrastructure is very costly, the time required for the preparation of the confined space entry and setup of the possible access method such as a scaffolding often results in tens of thousands of dollars in asset immobilization.

It doesn’t come as a surprise  that a large number of the industrials we talk to in power generation, oil & gas, water management, maritime and chemical industries are looking for new solutions to the challenge of replacing hazardous, slow and costly human entry for visual inspection.

The available solutions for Visual Inspection of confined spaces? 

On recently commissioned assets, a lot of work is being done on designs to limit the need for entry into confined spaces, but in most cases, it cannot be avoided completely.

DIY or industrialized “camera-on-a-stick”, or cameras lowered from the top of the confined space with wires can sometimes represent a very cost-efficient and effective solution to get images without human entry. These approaches are however limited to a small number of simple geometries as they cannot be operated beyond the spaces accessible with a 1-dimensional movement from the access point.

Camera-on-a-stick.jpg

Figure 1 - Searchcam's Recon - Camera designed for search and rescue

“Crawler” robots are the tool of choice for the inspection of long spaces with a consistent geometry such as pipes and ducts. Usually connected to the outside world  by a tether providing power and a data link, they allow to perform live inspection several hundred meters down a pipe for an unlimited time. However, they are mostly applicable in situations where there are no significant obstacles, T-junctions, or large change in the diameter of the pipe such as reservoirs.

Crawler-robot.jpg

Figure 2 - Pipe inspection crawler from Inuktun

Other notable developments include “snake” robots, that are able to enter through a manhole and be operated inside a tank to maneuver around the internals and access virtually any place located close enough from the entry manhole; the drawback of such systems being its large weight and footprint. Those systems are currently mostly at the prototype stage and we are not aware of scaled-up deployments.

Snake-robot.jpg

Figure 3 - "Snake" robot from the Petrobot research project

Finally, other bespoke robotics systems such as “climber” robots use magnets to climb vertical surfaces and thus freely navigate the surface of metallic confined spaces, provided that the environment does not feature sharp angles that might block the movement. While some miniature versions of such climbers have been developed, most “climber” robots are typically heavy and expensive equipment.  

Climber-robot.jpg

Figure 4 - GE Inspection Robotics climbing robot for boiler inspection


The case for drones
 

Using drone, or Unmanned Aerial Vehicles (UAVs) for indoor use, moreover in a confined and complex space could sound like a stretch, as most well-known use cases for drones feature wide open spaces that require coverage of large areas such as fields for agriculture or power line inspection.

However, UAVs have a serious advantage over other mobile robotics: their versatility. Their mobility in three dimensions allows to access virtually any place, from any angle, regardless of the shape, material and geometry of the environment.

This versatility also enables users to perform multiple tasks with the same device inside the plant, strongly shortening the time to return on investment. In addition, as those versatile tools can be often manufactured in larger volumes than bespoke machines, UAVs tend to be cheaper than custom ground robots.

However the use of drones indoors require one major problem to be solved: the risk of collisions. Indeed, in-flight collisions is the nightmare of any UAV pilot as a single contact can result in a crash and send the UAV to the ground. Even the best of the pilots cannot reliably avoid contacts with obstacles in complex confined spaces, moreover when flying beyond visual line of sight. Multiple other challenges await drones flying indoors: turbulences due to the small air volume or to drafts inside the confined space, presence of dust, signal transmission beyond line of sight, complete darkness and presence of reflective surfaces reducing image quality.

At Flyability, we tackled this issue through observing how insects solve this challenge: by using obstacles instead of avoiding them in order to navigate efficiently indoors. Think of a housefly finding its way out through an open window. Through specific flight algorithms and a mechanical design including a carbon-fiber decoupling system between the outer cage and the UAV itself, our Elios UAV can tolerate any collision in flight without perturbation. Moreover, on this drone designed for confined spaces inspection, the lighting and transmission system were designed to adapt to this particular environment.

This unique capability has won the trust of over 300 companies worldwide, which are using Elios to perform indoor visual and thermal inspection in confined spaces instead of sending workers in environments such as boilers, sewers, stacks or tanks.

An important limitation persist with the use of drones: the weight they can carry is limited by their size, and only small devices (for instance, Elios is only 40cm in diameter) can be conveniently used in small confined spaces. This means that they are unable to carry heavy sensors, but are perfectly capable of embedding cameras and thermal imagers.


Outlook: what can be expected in the coming 10 years?

By lowering the costs and risks associated to confined space inspection through robotic solutions, it is to be expected that these inspections will be performed more often, in order to further reduce the risk of an emergency shutdown or accident. We forecast that no human will have to enter confined spaces for inspection by 2025.

Gathering more comfortably and more frequently data will allow for predictive maintenance and to a greater digitalization of the assets.

Elios-entering-a-spherical-tank.jpg

Figure 5 - Flyability Elios drone entering a confined space

Drones will go in the direction of automated machines able to gather data without the intervention of any pilot. The data gathered will be organized on 3d models and analyzed to automatically identify defects and bring the attention of the asset operator immediately.

While the social and economic challenges arising from an increasing presence of robotics are numerous, their ability to go instead of us humans in dangerous, dull and dirty environments is definitely something we are looking forward to!

Check out our case studies

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