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The Company of Thermal Machines Studies (S.E.M.T.) was a company specialized in the design and construction of diesel engine until 2006 and is now operated as a brand by MAN Diesel and Turbo and its licensees.
In 2016, S.E.M.T. Pielstick celebrated its 70th birthday.
S.E.M.T. was set up by France’s ministry for industrial production with the support of five national companies: Société des chantiers et ateliers de Penhoët (Saint-Nazaire), Société Générale de Construction Mécaniques (La Courneuve), Société des chantiers et ateliers Augustin Normand (Le Havre), Société des Ateliers et Chantiers de Bretagne (Nantes), and Société des aciéries du Nord (Denain).The aim of the new company was to develop new engines in France that could then be licensed around the world.
Two years later, in 1948, the first licenses were supplied to engine builders.
In 1951, after its relocation at La Courneuve, the Société Générale de Constructions Mécaniques got equipped with the first test beds. The quipment, which enabled the company to speed up the development of a new range of engines, was later transferred to Saint-Denis and the subsequently to Saint-Nazaire.
In 1976, Althom-Atlantique was the flagship of French industry. The conglomerate becomes the majority shareholder of S.E.M.T. and the French licensees that build PA and PC engines.
In 1987, the German engine manufacturers MAN and MTU become shareholders in the company. MAN specializes in large engines, while MTU produces smaller, but high-powered units. The company, which also owns the Saint-Nazaire mechanical facility and a factory at Jouet-sur-l’Aubois, is renamed S.E.M.T. Pielstick after the widely known name of the company’s founder.
19 years later, in 2006, MAN purchases the shares bolonging to MTU to become the sole shareholder of the company. Then, in 2010, the diesel engine and turbo machinery activities are merged. The S.E.M.T. branding remains and is protected, but no longer appears as a company name.
The range of engines
- The PC range of engines, the founding engine.
The first PC1 engine is developed in 1951, and powered by heavy fuel oil in 1953. The first unit to go into series production is a six-cylinder, in-line engine (6 PC1 L) for the electricity generating plant of Bamako, Mali. With a bore of 400 mm, it develops 180 kW per cylinder. Its first marine application appears in 1955, aboard the ship Borée (two engines). The PC2 is launched at the start of the 1960s. Though it keeps the same 400 mm bore, power output is increased to 310 kW per cylinder – an increase that becomes a regular feature of the engine’s improvements in its subsequent versions: the PC2.3 in 1971, PC2.5 in 1973 and the 550 kW per cylinder PC2.6 in 1981. A dual-fuel version (gas and diesel) is also developed, while the range will have its final addition in 1995 with the PC2.6B long-stroke engine. This final version will feature a cast-iron engine mounting, a simpler design and a power output of 750 kW per cylinder – four times the power of the original model from 1953! The PC3 engine with the 480 mm bore is launched in 1969, with a power output of 700 kW per cylinder. The PC4 engine with the 570 mm bore appears in 1972, producing 990 kW per cylinder, which will increase with the PC4.2 version in 1981 to 1,215 kW per cylinder and the PC4.2 B long-stroke model in 1985 to 1,325 kW per cylinder. In its 18-cylinder version, the latter model is one of the most powerful four-stroke engines on the market.
- The PA engine range, a miniature PC.
The PA engines are high-speed units, running at more than 1,000 rpm. The initial PA1 and PA2 models can be seen as miniature versions of the PC engines, with a bore of 175 mm, and can be used for a wide range of applications – including powering submarines. The first turbo-charged version of the PA developed 46kW per cylinder at 1,250 rpm. Launched at the end of the 1950s and initially developing 110 kw per cylinder at 1,500 rpm, the PA4, with an initial 185 mm bore, is a completely new design. The work of Mr. Haug, it takes the principles of being compact and lightweight that were so cherished by Gustav Pielstick to a new level. It will later be developed with a VG version (variable geometry combustion chamber) and subsequently with a 200 mm bore to increase the power. A dual-fuel version (diesel fuel and gas) will also be developed. The PA4 VGDS with a twin-stage turbo to power naval ships is presented in 1978, generating 184 kW per cylinder. The final model in the range is launched 10 years later : the PA4 200 VGA for rail and naval applications, producing 165 kW per cylinder with a single-stage turbo. Specific versions for submarines are also developed: the PA4 185 SM, PA4 200 SM, and PA4 200 SMDS with twin turbo-charging.
- The PA6, a multi-purpose engine
Plans for a completely new engine begin to be laid from 1966 onwards. Launched as the PA6, it is designed to be the most powerful engine that can be fitted to a standard International Railway Union locomotive. The aim is to provide yet more power, at a time when diesel-electric traction still has a long way to go. The IRU approves the PA6 in 1971 and the first engines are produced the following year. A continuous process of improvement follows, with a range of different versions including the highspeed PA6 BTC for naval ships in 1975, the PA6 CL long-stroke engine with reduced fuel consumption in 1981 and the PA6 STC, which used sequential turbo-charging for naval ships in 1988. The final engines in the series will be the PA6 B and high-speed PA6 B STC in 1995, providing increases in power and overall performance. While these superbly-designed units do not enjoy commercial success in the rail market for which they were designed, they prove to be highly popular for naval customers. The PA5, the ‘little brother’ of the PA6, is launched in 1981 to meet an initial market demand from the Japanese fishing fleet. A dual-fuel version will later be developed (diesel fuel and gas) for electricity generating stations.
The major installations
- French Navy
S.E.M.T. Pielstick has provided PA and PC engines for the Georges Leygues, La Fayette, Floréal, Cassard and Horizon Frigates; A69 avisos; P400 patrol boats; the Jules Verne repair ship; the Durance type oil tankers; and the Foudre and Ouragan Landing Platform Docks. Nearly, the entire French fleet in the early 2000s was equipped with S.E.M.T. Pielstick engines.
- Exporting French know-how
S.E.M.T. Pielstick has also been involved in a number of export programs, such as the Saudi F 3000 S frigates (Sawari II program) and the Sigmaclass frigates for the Moroccan Navy (2 x 20 PA6B STC). Thanks to Fairbanks Morse Engines, license holder in the United States, S.E.M.T. Pielstick engines have also been chosen by the U.S. Navy, the largest and most demanding customer in the sector. The 16-cylinder PC2.5 STC engine has been selected by the U.S. Navy for its San Antonio-class LPD 17 troop transporters, which are each equipped with four engines and can carry until 800 marines. In fact, the PA and PC engines have enjoyed considerable success in countries around the world (including China, India, Britain, South Korea, Indonesia and Russia, along with the Japanese maritime safety agency) and are used by 60 navies to power their ships. It’s a story that still continues today, thanks to the efforts of our licensees.
- Submarines an envied technology
Gustav Pielstick designed the MAN 40/46 engines, considered the best in their class at the time, for the U-Boot of the German Kriegsmarine. After the war, S.E.M.T. enjoyed a considerable technological advantage in the field – which it maintained in the following decades. The PA4 engine was adapted for use by submarines, leading to the SM versions of the PA4 185 and 200. These were equipped with Hispano Suiza compressors – given the particular constraints in terms of air aspiration and exhaust gases within a submarine. The compressor also minimized the pressure variations created by the sea swell, increasing the reliability of the engine and therefore the safety of the entire propulsion system.
- Merchant shipping
Thanks to the network of licensees, the PA engines and the PCs in particular have enjoyed considerable international success since the mid-1950s in providing propulsion and electricity for merchant ships. Large ships (cruise liners, cargo ships and container ships) are traditionally equipped with medium-speed PC engines, while high-speed PA units are used in smaller vessels. Certain engines have meanwhile been designed for specific applications. Japanese licensee Niigata, for example, identified strong demand among the country’s fishing fleet – requiring an engine that would fit the trawlers exactly. The result was the design and development of the ‘little brother’ of the PA6, called the PA5, with a 255 mm bore. The optimized cost and low fuel consumption of the unit made it a great success around the Japanese archipelago. The propulsion systems needed for the large cruise liners built in the Saint-Nazaire shipyards also required a tailored solution. The nine-cylinder PC20 engines developed for the Sovereign of the Seas (268 meters) were mounted on rubber pads to reduce noise and vibrations in the cabins!
- Rail applications
Train locomotives have also been a major market for S.E.M.T. Pielstick engines. It was a new technological challenge for the design department as the power requirements of trains are far more varied than they are for ships. The “small” Piestick PA4 unit with a 185 mm bore was designed specifically for this market. Although it represents a limited activity today, rail transportation was a particularly large market in years gone by: 44,2% of all the engines produced in the history of S.E.M.T. were destined for locomotives.
- Nuclear and thermal power plants
Electricité de France began using S.E.M.T. Pielstick engines for its diesel-powered plants in the 1950s. EDF would subsequently remain a loyal customer when it later equipped plants in France’s overseas territories and dominions with 18 PC4.2 V engines – which were recently replaced with MAN 48/60 and 51/60 Dual Fuel units. The Saint-Nazaire production site has been entirely re-organized and is now capable of producing 50 such engines a year. MAN decided to support the Saint-Nazaire site because of its direct access to the port, thereby easing the transportation of equipment to customers. The PC engines for diesel-fueled electricity generating plants have also enjoyed considerable commercial success in Japan, with its archipelago comprising numerous islands that need to be autonomous in terms of power production. Today, MAN Diesel & Turbo France is able to deliver turnkey thermal power stations with auxiliary power units ranging from 125 to 19,000 kW. With its expertise in the combined diesel cycle (diesel engine and steam turbine) and the ability to use a range of different fuels – such as fuel oil, bio-fuel, heavy oil and gas – these plants offer remarkable flexibility at an operational level.
- Auxiliary units for nuclear plants
MAN Diesel & Turbo is a world leader in auxiliary power units for nuclear power plants. The units represent a key element in nuclear plant safety as they provide backup for its safety systems - should these lose their main source of power. S.E.M.T. Pielstick engines have been approved for such use in numerous countries because of their performance levels when taking over the supply of power, and also their reliability. They can even operate in the event of an earthquake or in extreme climatic conditions.
S.E.M.T. engines have been manufactured in many countries around the world. A total of 34 licensees produced its engines since the company started. Currently, there are eight: - Fairbanks Morse Engine – United States, - Doosan Heavy Industries & Construction – South Korea, - Shaanxi Diesel Heavy Industry – China, - Hudong Heavy Machinery – China, - JFE – Japan, - Diesel United – Japan, - Kawasaki Heavy Industries – Japan, - Niigata Power Systems – Japan. The licensing system provides opportunities in markets that would be inaccessible without a local partner, particularly in the nuclear and defense sectors. It can also lower the cost of the engines, depending on the country where they are manufactured.
1987: The actions are shared in 3:
- 49% by Alsthom
- 25.5% by MTU
- 25.5% by MAN
1990: Shares are shared equally by Alsthom, MTU and MAN (33.3% each).
2006: 100% of Pielstick's shares are held by MAN and become the sole shareholder.
Key figures as of 12.31.2016
45 550 692: It’s the amount of kilowatts delivered by all of the S.E.M.T. Pielstick engines produced since the company started.
24.8% of engines have been built in France whereas 75.2% of engines have been built abroad by licenses.
More than 15 000 engines have been manufactured to date.
373: it’s the number of emergency diesel generating sets in service around the world, with a combined power capacity of 2.392 MW.