Capstan Reel Installation System

Exploration and subsequent oil and gas production in ever deeper subsea environments have created a greater market requirement for a cost-effective means of installing pipes and cables to subsea assets in a safe, reliable and efficient manner.

Current pipelay systems require large towers, huge tensioners and high gripping forces all of which necessitate larger vessels with significantly higher costs. Parkburn has spent many years following and understanding the requirements associated with product installation and has used its own research and development activity to develop new capstan methods to combat the increase in both size and cost of the equipment in use today.

The new Capstan Reel Installation System approach “CRIS” has been developed utilising a slipping chain in combination with a large capstan to provide the main T1 tension handling component whilst smaller conventional tensioners provide the lower T2 holdback requirement. This method reduces significantly the gripping or handling forces being exerted on the product and the overall size of the installation on board the vessel. Qualification and feasibility of the system design has followed the DNV technology qualification process and many candidate vessel arrangements have been assessed for suitability of the CRIS installation on board. Parkburn believes that installation of a CRIS system will greatly improve the safety and reliability of the handling system on board the vessel plus provide significant reductions in overall capital cost. Whilst initially being developed for the installation of flexible pipe, the CRIS solution has also been adapted to the requirements of reeled and rigid pipe handling. Current system solutions are aimed at 200, 500 and 800t tension handling installations although other configurations can be provided.

The design process carried out a detailed review of current technologies to identify the “good” and “bad” features of each with respect to the ideal features list to be included within any new product or system design.

• Store the product at low tension
• Modify the standard traction de-tension, tension profile within the system to spread the work over a long section of product to minimise fatigue and slippage
• Ensure there is a fixed input and output from the system with no fleeting forces
• Reduction of compressive forces into product by more than 50%
• Compact, lighter and smaller system aimed at 40% of reduction in all areas
• Fixed mechanical machine with simple forward reverse function
• Multiple drive options

The result is the CRIS solution utilising proven capstan technology to take the product around a rotational centre line to create a natural helix and a slight elliptical cable path through the machine. The result in a unique de-tensioning or tensioning profile that spreads the work evenly throughout a long section of product as it passes through the machine allowing the product to move from a low tension storage condition to high tension “in water” mode in a controlled and safe manner.