ROVs, AUVs and AIVs

Underwater vehicles play major role in Ex environments

Remotely operated vehicles (ROV), often described as "robot submarines", have been used by the oil and gas industry for many years, mainly for underwater drilling, construction and installation, inspection, maintenance and repair jobs in the wells of offshore oil platforms. Equipped with very sophisticated electronic devices, they are the eyes, ears and hands of those who operate them from ships or offshore platforms.

Autonomous inspection vehicle (AIV)
Autonomous inspection vehicle (AIV) – Subsea 7 (Photo: Heriot-Watt University)

ROVs can reach depths to which no human diver could descend. They look like giant steel boxes, about the size of a small car. Their manipulator arms can pick up tools and some are capable of lifting weights of up to a tonne. They are deployed in a protective cage which carries them to their subsea location, from where they operate, sometimes in harsh conditions and very low visibility, to complete numerous subsea missions, from turning bolts to closing valves.

As an example, during the 2010 oil spill in the Gulf of Mexico, robotic submersibles were sent underwater to contain and ultimately cap the spill on the sea floor, where direct human intervention was impossible.

Going back in time

Attempts to develop a ROV were made as far back as the mid-1860s when Luppis-Whitehead Automobile developed a kind of torpedo, the Programmed Underwater Vehicle (PUV) in Austria. Almost a century later, in 1952, Dimitri Rebikoff, a French engineer, oceanographer and underwater photographer, built the first underwater scooter which evolved into the world’s first tethered ROV, named the Poodle.

In the 1960s, technological advances came from the US Navy. Their Cable-Controlled Underwater Vehicle (CURV) was destined to perform deep-sea rescue operations. A CURV was used to recover a nuclear bomb lost in the Mediterranean Sea after the 1966 Palomares crash of a B-52. Another CURV helped save the pilots of a sunken submersible off the Irish Coast in 1973.

Essential to the oil and gas sector…

The oil and gas industry quickly saw a future for ROVs: they could assist in the development and deployment of offshore oil rigs. From the 1980s onwards, ROVs have been used for an ever increasing number of tasks that could never have been undertaken by human divers, from the simple inspection of subsea structures, platforms and pipelines to connecting pipelines and placing manifolds.

…but not only

While the oil and gas industry has most certainly benefitted from the introduction of ROVs in its operations, other sectors have taken advantage of the technological advances that have allowed the development of a wide range of ROVs, from small inspection vehicles to deep ocean research systems. Those are used mainly for scientific applications. In 1995, an ultra-deep ROV, Kaiko, made by JAMSTEC, a Japanese firm, reached the deepest part of the ocean, the Challenger Deep in the Mariana Trench, at 10 909 metres.

Technological advances

Over the years, there has been a growing need for more powerful and more reliable ROVs that could go deeper and accomplish increasingly complex tasks. One major improvement, in the early 1980s, was the use of control data and video over fibre optic in the offshore oil and gas sector. This meant that ROVs, which previously used data over copper, could operate in greater depths.

Depending on their category, ROVs may be equipped with video cameras and variable lighting; acoustic and tracking sensors (tracking and measurement devices, scanning sonars, profiling sonars, bathymetric systems and pipe trackers); non-destructive testing sensors used to check structural integrity; cleaning devices (rotating wire, nylon brushes, water-jetting, etc.) to clean offshore infrastructure; and multiple single-purpose or multi-mode work tools; simple bars, hooks and knives. 

The lighter category of vehicles, fitted with camera, lights and sonar, are used mainly for observation, although some can perform basic manipulative tasks as well.

The much larger work-class ROVs are deployed in the drilling and construction support sector; they also do subsea pipeline inspection and monitoring. Heavy work-class ROVs are the most sophisticated: they can operate in deep water, have manipulators and grabbers that can lift huge loads and can perform tie-ins and subsea installations.

Today’s most technologically advanced ROVs, equipped with machine vision and motion sensors, can maneuver to a precision of 5-10 mm and attain high levels of safety and efficiency in subsea operations.

AUVs and AIVs

The emergence of autonomous robotic vehicles – self-driving cars, unmanned aerial vehicles (UAVs), industrial and domestic robots – and the groundbreaking technologies they’re associated with has also had an impact on underwater exploration. The development of vision-based robotic navigation has led to the development of autonomous underwater vehicles (AUVs) and autonomous inspection vehicles (AIVs).

AUVs and AIVs can be used for critical infrastructure protection, rapid environment assessment, search and rescue operations, intelligence, surveillance and reconnaissance, harbour and costal surveillance, offshore rigs, subsea work, mining, data gathering and deep water survey and inspection.

Docking stations placed on the sea bed allow AUVs to charge their batteries and AIVs also have their own station underwater, meaning that all power resources are dedicated to the missions they undertake and not wasted on dive and recovery processes.

Ex-proof equipment

Sensors, connectors, switches or cameras are just a few items that equip ROVs, AUVs and AIVs. When these vehicles are intended for the oil and gas industry, they have to meet very specific and strict requirements to be explosion-proof, as any equipment or material used in explosive atmospheres. The fact that they operate underwater doesn’t make any difference.

The IEC solution for Ex equipment

The IEC has been at the forefront in this field for many years, preparing International Standards and establishing a Conformity Assessment System that provides testing and certification for Ex equipment.

International standards

IEC Technical Committee (TC) 31: Equipment for explosive atmospheres, has a complete series of international standards that cover all specific requirements for Ex equipment and systems, from general requirements to protection levels for apparatus used by all sectors that operate in hazardous environments, such as oil refineries, offshore oil rigs, gas plants, mines, sugar refineries, flour mills, grain silos and the paper and textile sectors.

Safe access to global markets

Producing devices and equipment based on Ex standards is not enough. Most manufacturers and suppliers trade on the global scene and have to meet the very strict requirements put in place by national regulations and legislation. Proving their adherence to those requirements can be costly and time-intensive.

The IEC, through IECEx, the IEC System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres, has the mechanisms in place to help industry, authorities and regulators ensure that equipment (electrical and non-electrical) as well as the people working in Ex locations benefit from the highest level or safety.

The System is truly international and has been endorsed by the United Nations Economic Commission for Europe (UNECE) as the world’s best practice model for the verification of conformity to international standards for explosive atmospheres.

Accordingly, UNECE issued a UN Publication, A Common Regulatory Framework for Equipment Used in Environments with an Explosive Atmosphere, identifying the use of IEC TC 31 International Standards supported by IECEx Certification.

Testing and assessment under the IECEx certified equipment scheme are accepted in all its member countries and beyond. The System provides access to global markets and drastically reduces costs by eliminating multiple re-testing and certification.