Ultra-deepwater synthetic rope moor-ings are suffering damage during installation and pull-out, due to fric-tion imparted by the winch system. Depending on the level of tension exerted, some ropes can be written off after just one deployment.
Kley France, based in Rueil, west of Paris, says the problem is caused largely by the grooves of conventional winch capstans. Its own annular traction winch, developed initially for the oceanographic sector, could resolve this issue for offshore contractors.
The system, first introduced in 2002, was designed for Dutch and Norwegian research institutes seeking to deploy synthetic ropes weighing from 50-500 tons in deepsea applications. According to Project Manager Regis Baizeau, the fixed grooves prevalent on traditional winch capstans have no impact on steel wire ropes of a similar weight. With synthetic or hybrid (wire/rope) systems, however, the same paying-out operation leads to elongation of the rope as tension is increased, which can quickly develop into severe abrasion.
Kley's annular traction solution is designed to prevent friction arising as a result of drum/rope speed mismatch. The winch itself incorporates two drums with a smooth surface (stainless steel or ceramic coated), and annular grooves. The latter are made from synthetic materials, and are not permanently fixed. This approach allows the rope, whatever its strength or thickness, to slide freely over the drums.
The two other main components are a storage drum, speed-controlled to match the movements of the capstan, and equipped with a hydraulic or electrically operated spooling system, and a back-tension compensator. This maintains the tension required for both controlled spooling of the storage drum, and for tension-building via the capstan.
For oeanographic purposes, traction capacity can be adapted to the application (currently 4-400 tonnes). Kley is in talks with various offshore operators about adapting the winch for deepwater oilfield use, possibly involving trials in 1,000 m of water. Over the past few decades, the company has designed and supplied numerous riser and mooring pulling winches for operators and contractors such as SBM, Stolt Offshore, and Woodside Petroleum.
