Madsen Giersing (MG) was appointed by Puma Energy as the structural design engineers for the upgrade of the Bravo Jetty at Napa Napa Refinery, Papua New Guinea.
The upgrade of the marine facility was to accommodate Suezmax tankers up to 167,000 DWT. These works consisted of extending the existing loading jetty to allow for installing four new marine loading arms, a new berthing and mooring dolphin to the south of the existing dolphins and walkways linking the loading jetty and all dolphins.
The project required special care and consideration as the new design vessel was 167,000DWT compared to the original design vessel of 110,000DWT. In addition is an existing berth was located to the north of the facility and thereby restricting an expansion of the berth to the north.
Due to the size of the vessel and the northern berth, the design vessel, 275m overall length, was required to be berthed eccentric to the loading jetty. This resulted in the requirement of extending the existing loading platform and then addition of a new berthing dolphin and mooring dolphin was required to the south of the existing dolphins to safely moor the vessel for unloading of the crude oil.
The construction of the dolphins consisted of raked steel tubular piles and a concrete deck. To remove the requirement for overwater formwork the dolphin deck was constructed out of a precast concrete shell which was concrete filled insitu.
Capability of the existing dolphins to handle the berthing and mooring forces was also investigated. This resulted in the requirement for replacement of the existing fenders with a new fender of higher energy rating but with similar fender reactions to ensure the existing dolphins were not overstressed.
To provide safe access between the dolphins for the line crews, new walkways were provided. These consisted 21 to 43m long precambered steel tubes supporting a lightweight walkway frame.
Port Moresby, Papua New Guinea