Chilled out gas ca rrier

As part of its fleet renewal policy, Norwegian shipping company I.M. Skaugen (IMS) contracted the Hudong-Zhonghua Shipbuilding Group in Shanghai, China, to build a new generation of six ethylene LPG gas carriers known as ?super coolers?.

These state-of-the-art semi-refrigerated gas carriers have been designed, commissioned and built specifically to comply with the most stringent safety requirements of the petrochemical industry and will be operated by Norgas, an affiliate of IMS specialising in LPG and petrochemical gas shipments. The order, which was placed in August 2000 (first four ships) and May 2001 (last two ships) called for four units of 8,556m3 and two larger versions of 10,208m3 with four optional vessels of a size yet to be decided.

The first of the new six-ship series, Norgas Orinda, was delivered at the end of October and is of the 8,556m3 size built at a total cost of about $21.5 million. Although the original delivery date had been slated for the second quarter 2002, this is the yard?s first ever ethylene gas tanker and the learning process that was involved undoubtedly affected the pace of construction.

Nevertheless, the yard has met a revised delivery schedule and Skaugen has stated it is quite pleased with the build quality adding that the yard worked hard to ensure it produced a first class product. All tests and trials carried out have confirmed that the vessel exceeds specifications and performed better than expected.

With an overall length of 124.9m, the 8,860g vessel has a relatively wide beam of 19.8m and a shallow draught of 8.3m which enables it to load and discharge on an even keel and therefore able to handle a larger cargo intake in shallow ports. The new class has only two cargo tanks as opposed to the more common arrangement of four to six tanks found on similar ships. This design decision was based on Norgas? experience, which showed there was no requirement for so many tanks, and has resulted in a reduction of time spent on tank preparations prior to loading.

The two tanks give a total capacity of 8,461m3, have a 7 bar tank pressure and, when combined with the high cooling capability, will enable rapid turnarounds to be achieved when loading ambient LPG and propylene in southeast Asian ports where high temperatures are the norm. For example, the loading time of propylene at, say 25oC, is two or three days shorter than on a conventional vessel of similar size. Between four and ten days can be saved when cooling a cargo from 25oC down to -46oC. When it comes to discharging its cargo, the centrifugal deepwell cargo pumps are capable of accomplishing this in about eight hours, a feat that is helped by having a two-tank design and a short, direct piping to ensure fastest possible loading, discharging and cooling down.

This new generation of gas carrier also features a 95m3 deck mounted tank which, combined with an onboard nitrogen plant, enables the cargo tanks to be purged and prepared for new grades of gas products while en route to the next terminal ready for loading without shore assistance. The super cooling facilities allow the new series to carry fully refrigerated ethylene at -104oC, which is an important consideration since this product is the most significant cargo for Norgas followed by LPG and other petrochemical gases such as propylene, propane, butane and ammonia. The main investment in new petrochemical plant is currently taking place in the Middle East and Asia, notably China, and these two regions have consequently become primary sources for the production and shipment of ethylene.

Ship operators in this market have to service customers with widely diverse requirements and need to manage a mix of contracts, spot and time charter business in the most cost-effective manner possible. Vessels of the super cooler class offer Norgas maximum flexibility in trading and optimise earning capacity by providing the best possible service at the lowest cost through quick turnarounds in port. This is undoubtedly one of the main factors leading to profitable ship owning and Skaugen claims the new series is the most efficient in the market today.

Power plant

A single medium speed four-stroke 6L 48/60 MAN B&W diesel engine, with an output of 6,300kW, coupled to a Renk gearbox and driving an MAN Alpha VBS 1180 highly skewed four bladed controllable pitch propeller gives a service speed of 16.5 knots fully laden. With the emphasis on fast port turnarounds, the vessel is endowed with a high degree of manoeuvrability thanks to a 700kW Brunvoll cpp bow thruster and a Rolls Royce Ulstein Hinze flap rudder. Additionally, the series is fitted with an efficient and quick mooring system.

Auxiliary power comes in the shape of four MAN D 2824 LE diesel gensets each linked to a 600kW Stanford generator. The main propulsion is diesel mechanical while a shaft generator is fitted with PTO/PTI of 1,700kW/ 1,000kW giving the vessel a take me home capability in the event of main engine breakdown.

Vesting in innovation, safety, efficiency

To meet present and future environmental restrictions, the new ships will use 10% less fuel and energy compared to conventional vessels and the main diesel engine is compliant with proposed NOx regulations. Tin-free anti-fouling paint has been used while ballast water can be changed during sea passages enabling these vessels to meet the likely future requirement prohibiting the carrying of ballast water from one port to another where they are not in the same geographical region.

The ships are fitted with incinerators capable of burning waste and rubbish onboard and will also have equipment complying with MARPOL ?low sludge? notation. This enables all fuel residues, used lube oil and sludge to be reconditioned for further utilisation in the thermal oil boiler for heat generation or as fuel in the main propulsion engines.

With financial agreement secured by the Export Import Bank of China (EXIMBANK) for a 10-year buyers credit facility, ownership is vested in a Hong Kong-based company Somargas and the vessel is registered at and flies the Hong Kong Chinese flag. The second ship in the series is expected to be completed late December/early 2003 while the remaining four vessels are due for delivery at three monthly intervals with the last unit scheduled to enter service early 2004. These newbuildings will increase Norgas fleet?s capacity by about 55% although they will gradually replace the older 6,000m3 tonnage. The current Norgas fleet consists of 14 gas carriers with a total carrying capacity of 100,000m3 and the four options, a decision on which will be taken within the next six to eight months, could be delivered in 2004. The newbuilding project is also in line with the IMS strategy to strengthen Norgas?s position as the second largest ethylene carrier in the world.

Since 1996, the IMS Group has viewed China as a promising market for the transport of petrochemical gases and as a valuable source of affordable crew, fleet management services, shipbuilding and repair. Not only has the group shown its faith in China by building its ships there, it has also established, in partnership with the Wuhan University of Technology, a training center which prepares and certifies Chinese seafarers and provides a thorough training in the safe handling of dangerous petrochemical cargoes and other oil products. In addition, IMS also runs its own recruitment and training programmes in St Petersburg, Russia, for the crews of its vessels.

LNG next on Hudong-Zhonghua?s shopping list

As previously reported in The Motor Ship Hudong-Zhonghua has been pre-selected as a builder of two 147,000m3 LNG carriers for service between Australia?s northwest shelf and south China.

Sources at Hudong report that although a contract is yet to be signed this is apparently just a formality. The yard?s bid for the contract was greatly assisted by the input of French shipbuilder Chantiers de l?Atlantique, say sources, with this cooperation set to continue throughout the building of the vessels in the form of French workers providing project management and expertise.

It is virtually certain that both ships will be built in China, although the original plan conceived for one ship being built in China and one in France. Hudong is presently building an insulating box factory.

Construction is anticipated to commence late next year. The first ship is expected to be delivered in the third quarter of 2005 and the second unit is earmarked for spring 2006.