After several rounds of intensive tendering negotiations, detailed joint project planning and based on mutual cooperation, Subsea 7 chose Dormac Offshore to carry out the repairs to their Pipe-laying/Heavy Lift Barge “Seven Polaris” in Cape Town.
The project duration was 93 days and work was carried out around the clock, 7 days a week, as required by Owners, in order to complete all works. Extensive pre-arrival planning was organised with Subsea 7 and Dormac planners who worked together to optimise the schedule, including pre-fabricating the steelwork and around 80% of close to 6000m of pipework, which was required in order to meet the demanding schedule.
A critical success factor ensuring this tight delivery was the ability to carry out a 3D scan of all 6 engine rooms in advance and extrapolating this information into detailed “as build” CAD drawings of all the piping systems that required renewal. This resulted in the Yard capability to prefab the sch80 galvanized, and fully coated, pipe systems prior to the barge’s arrival. Pipe work included the refurbishment of the barges exhaust systems complete with new insulation and cladding.
Other mechanical work scopes comprised of the complete overhaul of; 4 x 40ton RR azimuth thrusters in workshops, 2 x bow & stern thrusters in workshops, 2 x Caterpillar Generators, 4 x Ulstein Bergen thrusters engines and the Wartsila Generators.
In order to execute the thruster overhauls, the barge had to be docked on 4,5m special concrete docking blocks specifically designed for the access to the thrusters.
Significant steelwork was carried out in the following areas; main deck, ballast tanks, spar deck, main crane boom and on the accommodation deck. Hydraulic repairs involved the overhaul of the main 1600ton Clyde crane winches, Manitowoc crawler cranes, ROV Launch & Recovery “A” frames, thruster steering motors and numerous other hydraulic system upgrades and modification.
The major electrical repairs include the overhaul of over 80 electric motors of various sizes, main alternators, bow & stern thruster motors (1,400KW), overhaul of switchboards and refurbishment of the main crane boom flood lighting system.
In preparation for the barge’s next employment the yard carried out the installation of a new 120 ton winch on the main deck. This required the new foundations and under-deck stiffening to be integrated into the hull structure. Also the hook-up of the control systems, power supply and hydraulics.
After the hull blasting and coating program was completed, all the hull fenders were replaced with new wooden fenders.
Despite almost doubling of the initial work scope, the project was completed within the original planned period. During the dry dock phase of the repairs, both Subsea 7 and the Dormac Offshore project teams operated from the same custom built project office, directly adjacent to the dry dock. These new, state of the art offices enabled close co-operation between both parties which facilitated in the rapid response to scope changes and planning.
Prior to and throughout the project, safety was considered paramount and was another key success factor on this project. The Dormac safety team produced a HSE bridging document which encompassed all the safety requirements of Dormac, Subsea 7 and Transnet National Port Authority. Due to the huge management focus on safety the yard carried out almost 3,000 inductions and this pro-active approach, coupled with the support of the Seven Polaris crew, ensured a zero lost time injury project for Dormac Offshore. In excess of 1,100,000 man-hours were executed, of which over 850,000 hours were actual performed on site.
The effective completion of the project, with strong emphasis on safety and quality proved that Dormac’s philosophy of safety first, ability to allocate dedicated experienced project teams, joint pre-planning and a focus on customer relationships contributed to a successful project that all involved were proud of.