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Jacket Crawler Robot
Steps In For Hazardous Jobs

A project presented by Morten Hesselager Pedersen, Hans Pedersen, Henrik Lisby, Søren Hansen and Kenneth Guldager

Morten Hesselager Pedersen

Best Innovators

The steel frame supporting an offshore platform is known as the jacket, and is particularly exposed to corrosion, but weather and sea conditions can make maintenance work in the vicinity of the water line extremely risky. This situation can compromise the efficiency, scheduling and safety of maintenance operations in the splash zone. To solve this problem, we worked with SubC Partner to develop an offshore maintenance robot called a jacket crawler. This remote-controlled robot, which can climb along the jacket, represents a major revolution in offshore platform inspection, maintenance and modifications.

The Hazards of Jacket Maintenance

Because the jacket of an offshore platform is hit by waves, it is particularly exposed to corrosion from seawater. Maintenance, inspection and other tasks are carried out by specialized teams of divers and rope access technicians. This work is risky due to the harsh weather and sea conditions. It’s often compared to being in a washing machine, as the divers have to remain stable while making sure they don’t get trapped under the structure as they carry out their work. These challenges can compromise the efficiency, scheduling and safety of maintenance operations.  

For a number of years, it has been too dangerous to carry out the inspection work needed on the Tyra platforms in the Danish North Sea due to subsidence of the field’s chalk reservoir, which has caused the platforms to sink six meters since first gas in 1984. Consequently, the structure designed to be above the water is now located in the water line. The field is currently being redeveloped to secure safe production in the future. As part of the project, numerous operations have to be performed to extend the lifetime of the existing jackets. One of these operations posed a major dilemma for the project team: as part of the redevelopment, we had to verify the structural integrity of the platforms — but the only way to do this was to send personnel into the dangerous splash zone.

A Very Short Innovation Cycle

To solve this problem, we decided to quickly design and manufacture a jacket crawler robot that could replace people in this hazardous work zone. In less than five months, the jacket crawler came off the drawing board and a prototype was tested offshore. It features numerous functions that were constantly enhanced as the project moved forward. These include the ability to grip onto the jacket, move along the surfaces to be cleaned, inspect the structure’s integrity and remove defective parts. The jacket crawler is connected to a cable that allows it to be remotely operated from a control room using six cameras mounted on the robot. The remotely operated vehicle (ROV) uses its two claws — with a grip strength of 500 kilograms — to crawl along the tubular structure, just like a bird sitting on a wire. Each claw is equipped with six wheels that allow it to rotate 360 degrees around the element to which it is attached.

The first prototype was successfully deployed in February 2018 and the robot solved this major dilemma by completely eliminating the need to send personnel into the dangerous splash zone.

A Reliable, Flexible, Multitask Solution with a Lower Cost

Four generations of robots have been developed since this first prototype to handle various tasks. The modular jacket crawler now takes different tools on its trips and carries out a variety of missions. For example, it was equipped with a diamond wire-cutting system to cut and remove non-essential structural items in the splash zone on the Tyra platforms. The latest version of the robot offers a wide range of functions, including the ability to:

  • Cut and lift structural parts weighing up to one ton.
  • Conduct ultrasonic thickness measurements from all angles with an accuracy of ± 0.1 millimeters.
  • Remove buildup of marine organisms with a 500-bar pressure washer.
  • Visually inspect welds close up with an integrated high-definition camera.
  • Perform work in waves up to two meters high.

The use of the jacket crawler on Tyra made it possible to conduct the offshore construction work safely and on time. Additionally, the project saved approximately $2 million on the first campaign by avoiding the major logistics and costs that would have been involved in deploying equipment and manpower from a diving support vessel. Only four people were needed to operate the robot. When it comes to halting and restarting work, this solution offers great operating flexibility at a marginal cost compared with diving support vessels.

Initially designed to clean marine buildup and measure steel thickness, the jacket crawler could also be used for jobs like sandblasting or painting. In theory, any tool can be mounted on the jacket crawler, customizing it for specific offshore jobs. Other industries have already shown an interest in this major innovation.

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