The first two of the latest Sulzer RT-flex50 common-rail marine engine type developed by Wärtsilä Corporation, have successfully completed official shop tests and class type approval tests at Wärtsilä's licensee Diesel United Ltd in Japan.
With five to eight cylinders, the Sulzer RT-flex50 low-speed marine diesel engine covers a power range of 5800 to 13,280 kW at 99 to 124 rpm. It is thus ideally suited to the propulsion of bulk carriers in the Handymax to Panamax size range, product tankers and feeder container vessels
The Sulzer RT-flex50 is based on the Sulzer RTA50 engine jointly developed by Wärtsilä and Mitsubishi Heavy Industries Ltd in Japan. Instead of the traditional camshaft-controlled systems of the RTA50, the RT-flex50 incorporates the latest electronically-controlled common-rail technology for fuel injection and valve actuation. The new technology provides great flexibility in engine setting, bringing benefits in lower fuel consumption, lower minimum running speeds, smokeless operation at all running speeds, and better control of other exhaust emissions.
Overall the Sulzer RT-flex50 engine is designed to meet the market needs for outstanding reliability, high efficiency, compactness, optimised industrialisation, and environmental requirements. As with all new marine engines nowadays, it is fully compliant with the NOx emission regulation of Annex VI of the MARPOL 1973/78 convention.
Two six-cylinder engines were involved in the tests at Diesel United's works in Aioi, Japan, each with a contracted maximum continuous power of 9720 kW at 124 rpm. The first engine completed its official shop tests on 21 July 2005 after a comprehensive programme of testing as is usual for a new engine design.
The second engine completed its official shop test on 13 August 2005. In the presence of representatives from the principal classification societies, it also successfully passed the type approval tests for Sulzer RT-flex50 engines and for the WECS-9520 electronic control system which is now incorporated in Sulzer RT-flex engines.
The first 6-cylinder Sulzer RT-flex50 engine is for export to Korea for a 37,000 tdw product tanker under construction at Hyundai Mipo Dockyard Co Ltd (HMD). The second 6-cylinder RT-flex50 engine will be delivered to Shanghai Edward Shipbuilding Co Ltd in the People's Republic of China for installation in a 19,625 tdw cargo vessel.
The new Sulzer RT-flex50 has been well received by shipowners. Altogether there are already 28 Sulzer RT-flex50 engines on order for newbuildings contracted with shipyards in China and South Korea for a variety of owners in China, Greece, Scandinavia, India and the Netherlands. They comprise two seven- and 26 six-cylinder engines, the newbuildings being 20,000 to 53,800 tdw bulk carriers and 37,000 to 52,000 tdw product tankers and LPG carriers.
The RT-flex50 is the latest Sulzer low-speed marine engine type to incorporate the unique RT-flex common-rail technology. A total of 205 RT-flex engines have been ordered, aggregated some 8.9 million kW. These include all Sulzer RT-flex engine types, from 500 to 960 mm cylinder bore, with individual engine powers up to 80,080 kW. The first RT-flex engine entered service in September 2001 and has accumulated some 21,000 running hours.