The Crosby Group, a leading manufacturer of rigging, lifting, and material handling hardware and equipment, has received a significant order for custom 115-tonne safe working load (SWL) sheaves to overhaul the drilling towers on a fleet of vessels.
These hulking drilling towers reach 65m above the deck of vessels that have been modified to drill oil and gas wells. Such drill ships are equipped with a drilling derrick; the sheaves handle the guiding of the wire to lift the drilling equipment up and down the tower (or derrick).
Roger Øvstetun, Manager, Engineered Solutions at The Crosby Group, said: “The Crosby Group offers a variety of sheaves that possess several benefits, meeting the requirements for this application and many more. This allows The Crosby Group to provide competitive solutions for a multitude of applications. We evaluate each incoming inquiry to make sure we supply the best type of solution. In this case, the ductile cast solution was the right choice for the application.
For this latest project, the sheaves each weigh 1.5 tons and meet EN 1563, DNV, and other relevant standards. With an outer diameter of 2,273mm, the sheaves will be used with 70mm-diameter wire rope to raise and lower drilling equipment.
The in-service vessels each have a drilling depth of nearly 12,200m (approx. 40,000 ft.) and typically work in 3,650m (approx. 12,000 ft.) water depth. They required a strategic overhaul, due to shortcomings with a previous solution, that had to be completed over a period. The scale of the order represents The Crosby Group’s continued ability to meet the offshore industry’s biggest challenges—from drilling to heavy lifting.
Øvstetun said: “Our broad knowhow on various sheave designs, makes, and types set us apart. Given the scale of these operations, we had to commit to delivery of sheaves that are geometrically optimized to handle stress and capacity. They are made from a proven material that has been optimized over time.”