In Depth: Sapura Diamante: Pressure can burst a pipe or make a diamond

Sapura Diamante is the first of five fully integrated pipe-laying vessels built by IHC Merwede for Sapura Navega^ao Maritima (SNM) from Brazil. With the contract signed early 2012, the keel-laying ceremony for the 550 ton pipe-laying vessels was conducted on 15 January 2013. The launch and naming ceremony was held on 27 September 2013 at IHC Merwede’s shipyard in Krimpen aan den IJssel and performed by Christina Lucia Duarte Pinho, the executive manager of Petrobras E&P Service. Sapura Topazio (YN 729), an exact copy of Sapura Diamante (YN 728), was launched in February 2014 and will soon join her sister in operation. The next three vessels for SNM (YN 730, 732 and 734) will be slightly different and are further away in the planning.

After successful sea trails and official handover to the client, the vessel is now on its way to the Brazilian waters to assist Petróleo Brasileiro S.A. (Petrobras) in the development of deep-sea oilfields in water depths up to 2,500 metres. In June 2013, SNM was awarded a contract from Petróleo Brasileiro S.A. (Petrobras) to charter and operate three Pipe Laying Support Vessels (PLSVs). The contract is for a period of eight years with an optional extension for an additional eight years.

With an overall length of 145.97 metres, the vessel is a diesel-electrically propelled DP2 mono-hull, built to Lloyd’s Class requirements. Port restrictions in the area where the vessel will operate, dictated that it has to be under 146 metres in length, hence the overall length. The beam of 30 metres is determined primarily as a result of the required stability, but is also influenced by port access requirements. The vessel is equipped with a vertical lay system, two cranes and twin ROV systems. The hull features two below-deck storage carousels for flexible pipe and a moon pool.

Sapura Navegacao Maritima

Sapura Navegacao Maritima is a partnership between Malaysia’s SapuraKencana and the Norwegian-managed Seadrill. The purchase of this series of pipe-layers and anticipated further fleet expansion is part of a continuous investment strategy by Seadrill and SapuraKencana in SNM. These additional vessels bring the total PLSV fleet in the region to six units and builds capacity in order to ensure that Petrobras has best in class support for their operations.

Seadrill is an offshore deep-water drilling company, supporting offshore energy companies in the exploitation of oil and gas fields. The company operates a versatile fleet of around 70 units, varying from semi-submersibles to deep-water drill ships and jack-ups to tender rigs, for operations in shallow to ultra-deep-water areas in challenging environments and sea-states.

SapuraKencana Petroleum Berhad (Sapura-Kencana) is an integrated oil and gas services and solutions provider. Their principal business includes providing end-to-end solutions and services to the upstream petroleum industry. This covers activities such as installation of offshore pipelines and structures, drilling vessels and underwater services.

It’s all in the family

Sapura Diamante is a completely IHC Merwede designed, engineered and built vessel, to which no less than 18 of IHC’s (internal) business units have contributed. This vessel is the first ever 100 per cent in-house built and ‘turn-key’ delivered PLSV produced by IHC Merwede. Celebrating their 70th anniversary it seems appropriate to highlight this special occasion and the contributing business units.

No 4 MbH Juni-Juli 2014 voor Website.jpg 42 2IHC Merwede comprises four divisions, all of which have specific areas of operation and expertise: Dredging, Mining, Offshore and Technology & Services. Being a PLSV it is only logical that the vessel was constructed at the Offshore Division, based in Krimpen aan den IJssel. This, however, is intensively supported by a number of departments of the Technology & Services division.

The pipe-laying outfit is designed by IHC Merwede’s subsidiary IHC Engineering Business and built at the their facilities in Sliedrecht. IHC Drives & Automation is responsible for the delivery of the integrated automation system, the full electrical installation and the complete electrical machinery package. They, in turn, were supported by IHC Systems who provided PLC IO cabinets and the pipe-laying simulator.

Looking specifically at the production aspects: IHC Metalix provided the steel package for the hull, whilst IHC Piping provided all piping and IHC Interior was responsible for all carpentry work. IHC Offshore Systems developed and delivered the moonpool, including bottom doors, and IHC Hytop was the partner for the hydraulic systems. To complement the pipe-lay equipment, IHC Vremac Cylinders supplied the hydraulic cylinders for tilting the tower. To complete the circle, IHC Parts & Services facilitates an on-going crew training programme and supplied the spare parts.

No 4 MbH Juni-Juli 2014 voor Website.jpg 42 3There are also a range of IHC related companies, not having this link incorporated in their name, like Atradius for insurances and MTI Holland, IHC Merwede’s technology development centre. Just to name a few… Indeed the conclusion must be: IHC keeps it all in the family. The advantage for the client: only one point of contact.

Accommodation and wheelhouse

The superstructure of the Sapura Diamante is located forward; it has accommodation for 120 persons, featuring generous staircases and an elevator. The pipe-lay tower is located just aft of the superstructure allowing for a large aft deck for storage and pipe equipment handling.

No 4 MbH Juni-Juli 2014 voor Website.jpg 42 4Deck ten is an approved and fully certified helicopter platform, with adjoining reception area and changing room. Deck nine, the wheelhouse deck, has two effective bridges: the forward facing part, used solely for transit sailing and the aft facing part, with a fully integrated bridge console supplied by SAM Electronics, is used solely for transit sailing. The area is where the DP can be controlled during pipe laying activities. Between the two bridge areas are the safety centre, captain’s office, sanitary and pantry facilities.

Deck four to eight are completely dedicated to accommodate all crew and client’s personnel. These five decks comprise of cabins, offices, conference rooms, storage spaces, luggage rooms, changing rooms and a hospital ward. For the well-being and relaxation of all personnel, the ship has a lounge/video room, internet lounge, smoking lounge, library and fitness room. Lastly there are the linen store, laundry, mess room, galley and provision stores. To conduct the vessel’s everyday tasks, we find a survey and an operations room, dedicated to control and monitor all survey, pipe laying and lifting activities. Besides the AC rooms, the only technical space to be found on these decks is the emergency/harbour generator room.

No 4 MbH Juni-Juli 2014 voor Website.jpg 42 5On both sides ofthe open deck oflevel five and six, the m.o.b. boat, the lifeboats and life rafts are to be found, each with dedicated davit installations and cranes. All decks below the fourth deck are filled with technical spaces. Here we find, amongst others, the engine rooms, separator rooms, bow thruster rooms (four in number), the engine control room, switchboard rooms, workshops and storages for various machine/engine parts and equipment. The forepeak, as well as housing the anchor equipment and chain lockers, is also reserved for a boatswain’s store and a paint store.

Propulsion and power

The ship’s power (23,040 kW) is generated by two groups of three 3,840 kW (4,100 kVA) Wartsila diesel generator sets, through two IHC D&A main switchboards, in separate watertight compartments as is required by the DP2 notation. The generator sets themselves are located in two full width engine rooms, one in front of the other. Main propulsion is provided by three fixed pitch/variable speed azimuthing Wartsila propulsors of 2,950 kW rating, which can be demounted underwater without dry-docking the vessel. For DP (on site) operations and harbour manoeuvring two 2,400 kW retractable azimuthing thrusters and two 2,200 kW tunnel thrusters are provided in the bow, all also Wartsila delivery.

The electrical installation comprises of an energy system with a high level of redundancy, featuring a low and high voltage (22 MW) installation. These systems are fed by Hyundai generators and controlled through frequency drives.

Cranage equipment

One of the major requirements for this type of vessel, to be able to handle all pipe equipment, is on-board hoisting capacity. For this, a large heave-compensated IHC mast crane of 250 metric tons lift capacity and a wire length of 2,500 metres is placed on starboard side amidships. The second auxiliary crane is a knuckle boom type of 20 metric tons, which is on starboard side aft.

Flex laying

Before departing for the work site, the carousels must first be loaded with pipe. To accommodate pipe loading over the stern, the vessel’s transom is provided with chutes. The pipe is then fed through a loading tensioner on deck and passes over intermediate guide chutes, before being loaded into one of the carousels. Maintaining the correct tension in the pipe, while loading or laying, is crucial to achieving its successful seabed deployment, as well as for the avoidance of equipment malfunction and associated downtime.

Sapura Diamante is fitted with two under-deck storage carousels each with integrated loader arm, of which the forward has a capacity of 2,500 tons and the aft one of 1,500 tons of flexible pipe. Electrical motors drive the carousels via a gearbox and a rack and pinion drive. A spooling device (or pipe guide) is part of the system and all (carousel) system components are synchronised with each other, as well as with the above deck tensioners. As icing on the cake, the core diameter of the carousels can be increased by means of placing a so-called ‘false core’ (a cage like structure) in it. Thus, when using smaller diameters pipe or when less pipe length is required, only the outer portion of the carousel is filled, results in higher unloading speed during the laying process.

However, the most notable features of the lay system is its pipe-lay tower, placed almost against the superstructure and kept upright by two adjustable cylinders to the superstructure aft bulkhead. With a total top tension capacity of 550 tons, it is permanently installed on deck for deployment of flexible pipe products with diameters ranging from 100 to 630 millimetres. The lay tower can be tilted and operate at an angle up to ten degrees from vertical, to accommodate laying (or recovering) in shallow water, thus increasing the pipe radius and reducing stress and possible fatigue.

WMN No. 4 2014 42Two tensioners of 275 tons are fitted on the aft side of the tower to keep tension in the pipeline, while it is being lowered onto the seabed. The tensioner control system monitors the outboard pipe tension and paid out length as part of the lay process, whilst at the same time giving feedback to the lay speed setting coupled to the vessel’s DP system. The tensioners, fitted with wire centralisers, are hinged to starboard side to clear the ‘firing line’. For obtaining an air draught of 48 metres, the top of the ramp assembly, as well as part of the aligner wheel, can be tilted aft. The tower crane can also hang down in ‘paralysedmode’ to reduce the air draught. The flexible pipe is spooled from one of the horizontal carousels (or baskets) to the forward side of the tower, then curves over the top wheel and is guided to the aft side, through the tensioners, down into the moon pool and onto the seabed.

To connect pipe sections, Pipe Line End Terminations (PLETs) are used, which are stored in a dedicated space on deck. Transport of the PLETs from their storage position directly into the ‘firing line’ is simplified due to the orientation of the pipe-lay spread with the moon pool aft of the tower. Once a PLET is loaded and in place, it is lifted up to align with the tower and moon pool, in which the previously installed pipe section is retained on a hang-off clamp.

Hang-off clamps are used to hold the pipe when it is not suspended by other means such as tensioners. The hang-off clamp supports the pipe by means of friction, using pressure cylinders to generate the holding power. The moonpool is designed to hang off pipe assemblies up to 600 tons and is also fitted with a mechanism to allow this assembly to be rotated under full load. When not in use, the moonpool can be closed by means of bottom doors, controlled and monitored by a system developed by IHC Offshore Systems.

Should such a situation arise, like a weather change, that operations have to stop and the ship has to abandon the site, the pipe end is terminated, lowered to the seabed and released. Once back on site, the end of the pipe is recovered and manipulated back into the moonpool. For this, Sapura Diamante is equipped with an A&R (Abandon & Recovery) system, featuring two winches of 610 tons and 200 tons, containing 3,500 metres of wire each with a diameter of 138 millimetres and 76 millimetres respectively.

RQUs

Sapura Diamante is equipped with two over the side launched ‘work class’ Remotely Operated Vehicles (ROVs), complete with their own launch and recovery systems. They are located just aft of the superstructure one either side of the vessel on main deck. The ROVs are capable of working to depths of 3,000 metres.

Conclusion

With this vessel IHC Merwede delivered a logistically and ergonomically well-balanced PLSV. The vessel has been produced primarily using IHC Merwede’s own resources and through intense collaboration between their own divisions.

Tom Oomkens

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