Jurong Shipyard Skids Hull in Rig Construction

Jurong Shipyard Pte Ltd (JSPL), a subsidiary of SembCorp Marine Ltd has skidded the massive 14,000 ton upper hull of a $285 million semi-submersible rig over the lower hull. It is reportedly the first of its kind involving the skidding of such a heavy structure. It was conceived, designed and constructed over a two-year period. On April 11, 2001, JSPL in collaboration with associated company PPL Shipyard Pte Ltd (PPL) entered into a fixed price agreement with GlobalSanteFe Corporation (GSF) for the construction of two units of Friede & Goldman ExD designed deepwater semi-submersible drilling rigs. Valued at $285 million each, inclusive of equipment, project management and other services furnished by client, the agreement also covers options to build two additional units of semi-submersible to be exercised at specific dates. The scope of work entails furnishing labor and materials to design, construct, equip, complete, test and deliver afloat to GSF these drilling units. JSPL designed and embarked on a construction methodology in which the upper and lower hulls were built simultaneously in two halves, a departure from the traditional method of installation by small sub-blocks onto the lower hull while afloat using floating cranes. Weighing approximately 14,000 tons, the upper hull, measuring 8.6 metres in height and 75 metres in length and width, was built on land that was reinforced to take the substantial load. The upper hull was then fully outfitted with installations, including a drilling tower. The lower hulls, consisting of two pairs of pontoons and columns, were built separately in JSPL’s No. 5 Drydock and subsequently shifted into position in the No. 3 ULCC Drydock prior to the skidding and mating operations. This Drydock measures 380 metres in length, 80.2 metres in width and 14 metres in depth. During the skidding process, the upper hull, which was constructed on land over the skid truss, was connected to 12 skid shoes. The keel blocks and supporting truss were then laid on the ULCC Drydock. The skidding beam on which the upper hull was skidded on had a length of 188 metres, inclusive of land and drydock area. Upon satisfying the regulatory requirements, the upper hull was then pulled by four computer-controlled hydraulic-operated strand jacks. The whole process took 11 hours to complete and was well within the planned schedule. Scheduled for delivery in the first quarter of 2004, the accomplished engineering feat has placed Jurong Shipyard in the league of the world’s new rig building yard.