Self-elevating service vessels have been in service in the US offshore oil and gas industry since the 1950’s. More commonly termed liftboats, they are characterized by a self-propelled vessel hull that can be elevated above the water and suspended on tubular or lattice-structured legs. They provide a stable working platform, increased crane capacity, and minimize down time due to wave action. In an industry with relatively high capital and operational costs, liftboats present increased value with efficient turnaround times within a safe work environment. The key design feature that creates the value for these vessels are the jacking systems which lift and hold the vessels in the elevated positions for performing work.
Supreme Integrated Technology, Inc. (SIT) and its subsidiaries have provided over 65 jacking systems over the past 50 years through SIT, and its predecessors Huber Inc. and Hydraquip Custom Systems. Typical jacking systems supplied by SIT are of the rack and pinion configuration and include custom-designed gearboxes and climbing pinions to meet any jacking and load requirements. The systems fall into two categories, electro-hydraulic and fully-electric.
Electro-hydraulic jacking systems consist of hydraulic power units (HPUs) powered by electric motors. These units consist of redundant pump and motor groups used for increased vessel safety and redundancy of operation. Generally, an HPU is provided for each leg to minimize installation costs yet provide a robust power supply in a small footprint thanks to the increased power density of hydraulics. The overall jacking operation is controlled via a master proportional control system that is operated from the bridge of the vessel.
Fully electric jacking systems replace the HPU in the electro-hydraulic version with variable speed drives (VSDs). [MD1] These drives are provided with built in programming and feedback to increase the level of control of the jacking motors. The increased control allows for an increase in overall system efficiency with programmed load sharing between each drive. The overall jacking operation is controlled similarly to the electro-hydraulic version from the bridge of the vessel.
The master control system for both options consists of an operational console with joysticks for proportional control. The PLC incorporates intuitive monitoring that provides industry-leading smoothness of operation with custom HMI viewing panels for ease of operation. The HMI panels provided can be based on SIT-standard templates or customized to fit customer preferences. Remote access of the control system and HMI screen is also available using secured connections for general troubleshooting.
Today, SIT jacking systems are operating in vessels across the world: in the surrounding waters of the US, Mexico, Middle East, Europe, Southeast Asia, Nigeria, and the North Sea. With vessels operating globally, SIT has developed a network of equipment providers and service specialists to provide the highest quality support for its systems. There is newer market development, as several vessels with SIT jacking systems have recently been utilized in the wind turbine installation industry for offshore wind farms. SIT is excited to continue to provide these systems on an increasing global scale for both the offshore oil and gas industry and the offshore renewable resources industry.