By Geert van der Zalm,
Marketing Manager at Bosch Rexroth
It was the biggest assignment Bosch Rexroth from Boxtel had ever faced, and it took more than two years to carry it out. The opportunity to research and supply the hydraulic components and associated local controls for the innovative lifting system on board the Pioneering Spirit, conceived and developed by Allseas, was met gladly.
The request came from Allseas, an offshore specialist, who specially designed the vessel to lift entire offshore platforms on or off their piles, in a single movement. To be able to do so, Allseas had developed in-house a complete motion compensation system and associated controls. The company also wrote the software for the principle behind the motion system. It was then that Allseas asked Bosch Rexroth to further develop the design of the hydraulics and the arrangement of specific components of these lifting beams, and to supply specialist hydraulic components and drive systems.
Enormous efficiency gains
It used to take vessels with cranes and dozens of workers weeks or even months to construct or dismantle a platform piece by piece on the open ocean. Pioneering Spirit, 382 meters long and 124 meters wide, can lift the top section of a platform off its piles in nine seconds. The motion compensation system is activated during preparations to pick up a platform.
It consists of 16 lifting beams operated from the bridge of Pioneering Spirit. Using the lifting beams, a platform is raised 2.5 meters in a single swift movement so that the topsides of the platform become detached from the substructure. Then the ship moves away, and the topside is carried towards the shore. The technology applied in this situation, also known as ‘swell compensation’, is exceptionally complex due in part to the simultaneous movements of the lifting beams along multiple axes.
Grasp the opportunity
Having already worked with Allseas on past projects, Bosch Rexroth had already supplied all sorts of components for special ships laying pipelines in the ocean. It was an opportunity to display their technological knowhow. Working closely with the Allseas engineers, who developed the unique form and functionality of the ship and the principle of the lifting beams for the topside lifting system, the engineering team investigated various technical control options for the individual lifting beams.
They looked at many different variations: hydraulic, electrical, and hybrid combinations of both technologies. The hydromechanics and electro-mechanics were a challenge, but so was the digital technology (controls, software, bus systems, etc.). Allseas wanted the ship to be able to handle platforms weighing up to 48,000 ton, which is not an easy task. It has to be done fast as well as accurately.
During the development process countless tests were carried out and simulations performed so that, together with the engineers at Allseas, Bosch Rexroth could find the optimal solution. After a couple of years’ of development the solution looked correct ‘on paper’, Bosch Rexroth were given the job of manufacturing and supplying the hydraulic components and drive systems for the individual beams.
Engineered to order
Aside from a few catalog components, such as valves and plunger pumps, most of the Bosch Rexroth components and subsystems were developed specifically for the Pioneering Spirit. This includes cylinders, controls systems, generators, mounting plates, etc. The local digital control systems that we supplied for the lifting beams were also developed specifically for this assignment. That applies to both the control hardware and the software.
During the design process, Bosch Rexroth made intensive use of powerful simulation tools to predict system behavior, finite element methods to compute critical parts and components for strength, and analysis techniques to identify risks in the process flow. The first real test was a project that took place last August, and involved lifting the 13,500-ton topside of the Yme platform, off the Norwegian coast. It worked well. Since then, the remaining four lifting beams (including Bosch Rexroth components) have been installed on the vessel, preparing the megaship for even larger lifting jobs.