Wärtsilä RT-flex68 / RTA68
Economical propulsion of tankers & bulk carriers up to 150,000 dwt
The Wärtsilä RT-flex68 and RTA68 provide excellent power and speed reliability for a wide variety of ship types from Handysize and Handymax up to Capesize and Suezmax.
Available in 5-cylinder up to 8-cylinder configuration, the Wärtsilä RT-flex68 and RTA68 low-speed engines cover a power range from 10,950 to 25,040 kW at 76 to 95 rpm.
The Wärtsilä RT-flex68 and RTA68 engines are fully compliant with the IMO Tier II exhaust emissions regulations set out in Annex VI of the MARPOL 73/78 convention.
|Wärtsilä RT-flex68, version D / RTA68||IMO Tier II|
|Cylinder bore||680 mm||Fuel specification:|
|Piston stroke||2720 mm||Fuel oil||700 cSt/50oC|
|Speed||76-95 rpm||ISO-F 8217:2005|
|Mean effective pressure at R1||20.0 bar||category ISO-RMK700|
|Piston speed||8.6 m/s|
|Rated power, principal dimensions and weights|
|Cyl.||Output in kW at||Lenght A
|95 rpm||76 rpm|
|5||15 650||10 950||12 500||10 950||7 530||386|
|6||18 780||13 140||15 000||13 140||8 710||439|
|7||21 910||15 330||17 500||15 330||9 890||496|
|8||25 040||17 520||20 000||17 520||11 070||552|
|4 300||1 520||10 400||4 700||12 545||2 340|
* Standard piston dismantling height, can be reduced with tilted piston withdrawal.
|Brake specific fuel consumption (BSFC) in g/kWh|
|Part load, % of R1||85||70||85||70||60|
|RT-flex tuning variant||Standard||Standard||Delta||Delta||Low-Load|
|** These BSFC values are for engines equipped with the latest high-efficiency turbochargers. Application of the previous generation of turbochargers leads to BSFC values that are 2 g/kWh higher. Delta Tuning and Low-Load Tuning are only available with the high-efficiency turbochargers.|
Dimensions and weights
- All dimensions are in millimetres and are not binding.
- The engine weight is net in metric tonnes (t), without oil and water, and is not binding
- All brake specific fuel consumptions (BSFC) are quoted for fuel of lower calorific value 42.7 MJ/kg, and for ISO standard reference conditions(ISO 15550 and 3046).
- All given BSFC figures for Wärtsilä engines are given with a tolerance of +5% across 40–100% of engine load.
For engines Wärtsilä X62/72/92 & RT-flex82T-B, RT-flex58T-D ER-3, stepwise tolerances are now introduced for the brake specific fuel consumption (BSFC):
- 5% tolerance for 100% to 85% engine load
- 6% tolerance for 84% to 65% engine load
- 7% tolerance for 64% to 25% engine load
Standard Tuning, Delta Tuning, Low Load Tuning are available for the electronically-controlled common- rail engines providing optimum fuel consumption and flexibility for different engine loads.Delta Tuning focuses on reducing fuel consumption in the operating range below 90% engine load. Low Load Tuning reduces fuel consumption below 75% engine load.
Rating points for Wärtsilä low-speed engines
The engine layout fields for Wärtsilä low-speed engines are defined by the power/ speed rating points R1, R2, R3 and R4 (see diagram). In certain engines, the layout field is extended to the points R1+ and R2+. R1, or R1+ instead if applicable, is the nominal maximum continuous rating (MCR). Any power and speed within the respective engine layout field may be selected as the Contract-MCR (CMCR) point for an engine.
ISO standard reference conditions
- Total barometric pressure at R1: 1.0 bar
- Suction air temperature: 25 °C
- Relative humidity: 30%
- Scavenge air cooling water temperature: 29 °C
All Wärtsilä low-speed engines are fully compliant with IMO Tier II NOX limits specified in Annex VI of the MARPOL 73/78. They can also be equipped with a SCR catalyst to meet IMO Tier III NOX emission levels and a scrubber to reduce SOX emissions to 0.1% – even with high sulphur fuels.
The Pulse Lubricating System with electronic control of lubrication timing has been further developed. It is available for all Wärtsilä Generation X, Wärtsilä RT-flex and for selected Wärtsilä RTA engines. The guide feed rate for new engines equipped with Pulse Jet cylinder lubrication system is 0.6g/kWh. Engines with different Lubricating Systems might require a higher feed rate. This allows important savings in engine operating costs.
Wärtsilä common-rail system
With the common-rail system, fuel oil, servo oil and control oil are delivered at regulated pressures to rail pipes arranged along the side of the cylinders. Electronic control units then regulate delivery from these rail pipes for fuel injection and exhaust valve operation.
In this way, the Wärtsilä low-speed engines have complete flexibility in fuel injection timing, rate, pressure and volume, as well as in exhaust valve operation. This provides engine operational benefits that cannot be obtained with mechanically-controlled systems.
Conditions for use
The 2D and 3D models and drawings downloaded (”Marine Solutions Drawings”) are for general guidance purposes only and should not be used for actual projects. Models and drawings for specific projects must be obtained from the appropriate Wärtsilä personnel as there may be deviations from the Downloadable Files.
File formats supported include DXF and PDF for 2D models and IGES, STEP, DXF, SAT and WRML for 3D models. A 2D DXF or PDF should always be used to support the 3D models. The Downloadable Files are subject to changes or improvements by Wärtsilä without notification so please check regularly for new and updated files at www.wartsila.com.
Wärtsilä takes no responsibility for and disclaims any liability for the contents of the Downloadable Files, including but not limited to omissions, errors, deficiencies, inaccuracies contained therein, and the use or misuse thereof. In no event, shall Wärtsilä be liable for any consequential, special, contingent, or incidental damages or injury, financial or otherwise, suffered by any party arising out of, connected with, or resulting from the use of the Downloadable Files or the information contained therein.
This website contains information, which is owned by or licensed to Wärtsilä. Wärtsilä shall retain all rights, including copyrights, relating to the information in the Downloadable Files. Reproduction or transmission to third parties is prohibited without prior written approval of Wärtsilä. Copyright© 2012 Wärtsilä.
- New two-stroke gas engine sets NOx emissions benchmark PDF, 418Kb »
- Combustion Control and Monitoring of two-stroke engines PDF, 312Kb »
- Propulsion solutions for medium-size vessels PDF, 272Kb »
- Making the most of perfect maintenance timing PDF, 169Kb »
- Cylinder lubrication of two-stroke crosshead marine diesel engines PDF, 639Kb »
- Wärtsilä R&D is responding to increasing concern about particulate emissions PDF, 102Kb »
- Cutting cylinder oil costs without a break in service PDF, 612Kb »
- Engine safety enhanced with wireless temperature monitoring PDF, 215Kb »
- Wärtsilä and Mitsubishi move closer PDF, 167Kb »
- Helping shipowners cut fuels bills with Wärtsilä low-speed engines PDF, 189Kb »
- Making the most of perfect maintenance timing PDF, 139Kb »
- Next steps in exhaust emissions control for Wärtsilä low-speed engines PDF, 193Kb »