SEMT Pielstick was a French company that designed and built large diesel engines. Its full name was Société d’Etudes des Machines Thermiques (Company of Thermal Machines Studies). Founded in 1948, SEMT was bought by MAN Diesel in 2006 During its existence as an independent company, SEMT manufactured engines for locomotives, naval vessels, power plants, and merchant ships. Its customers included France, the United States, Russia, India and other countries.