Carigali Hess contracted the flare specialists of Conbit to perform a major overhaul of the flare system at the Central Processing Platform at the Cakerawala field which is located offshore in the lower part of the Gulf of Thailand approximately 150 km northeast of Kota Bharu.The scope of the project comprised the replacement of the complete flare tip access platform, the permeate flare tip, two HP flare tips, two headers of the HP flare tips, and a manifold.
The operator evaluated two main alternatives for the major overhaul. The first option is to perform the maintenance using a large crane vessel which would be stationed alongside the platform and replace the damaged components. The alternative option which involves temporary lifting equipment that is installed at the top of the platform was offered by the experts of Conbit.
ENGINEERING & EQUIPMENT
A unique base frame was designed to connect to the side of the flare tower and the lift gantry rests on the flare tower structure to lift all components between its legs. The lifting system is operated by winches, which remain at deck level. Items that were replaced were lifted directly to and from a supply vessel. This system offers a controlled way of lifting. The lift system is tested before shipment to the project side and tested again before using it to lift the components. The safe working load of the lift system is an impressive 13.5 tons.
LIFTING OLD & NEW FLARE COMPONENTS
All components such as old flare tips, header, and rigging lines were lifted from the top of the flare tower directly to a supply vessel respectively. The major lift was the removal of the flare tip access platform. The weight of this platform was more than 7 tons. It was smoothly lifted directly to the supply vessel. After installation of the new manifold, header, and flare tips, the project was concluded successfully.
The full scope was completed successfully within a 10-day shutdown period. In that narrow window, an offshore crew of 20-30 colleagues with different skill sets installed and load tested the lifting system, replaced components with a combined weight exceeding 20t, and demobilized from the platform.
The project was a unique example that proves once again the use of temporary lifting systems as an alternative to large crane vessels to be very effective and safe.