Project: Golar LNG Offshore Mooring Structure
Client: Golar LNG Energy
Contract period: Jun 2011 – Dec 2011
Scope of work:
Construct Only – Mooring Structure
Contract sum: EUR 16 million
The mooring that Decorient has constructed outside Tanjung Priok, Jakarta, is suitable for the permanent berthing of an FSRU and the delivering LNG carriers which will be moored alongside the FSRU. The FSRU receives LNG offshore from the LNG carriers, which is then transported to shore through pipelines.
The basic concept behind the project looks simple enough: fabricate the piles and build the topsides, then take them on a barge to site and put them into place. The twist: dimensions were slightly off the regular scale. Each pile is 60 metres long with a diameter of 4.5 metres and weighs up to 325 ton.
The project’s design, the fabrication of the piles and the top sides were carried out almost simultaneously. The piles were being assembled in a fast lane precision yard near Singapore. Assembly of the piles took place in three stages; first steel plates ranging from 30 to 60 mm were rolled into cans. These were then spliced inside a workshop until their combined weight reached the maximum the workshop’s gantry crane could lift. These sections were then transported outside, where they were joined under two bigger gantry cranes. Finally, the lifting of the full-length piles on self-propelled modular units (SPMT’s), required the combined use of the two gantry cranes and a 250 ton crawler crane.
At the quay wall, the 800-ton crane barge loaded the 10 piles on its deck and transported the piles to the site, 15 km off the coast of Jakarta. There the crane barge, specially equipped with a 800-ton ringer crane and a 110-ton piling hammer, drove the piles to a depth of 40 meters. The nine topsides, ranging in weight from 18 to 125 ton, were fabricated near Singapore as well and were transported to site on separate barges.