Société d'Etudes et de Montages (SDEM) Erectors Nigeria Limited  was founded in Nigeria in 1981 as a subsidiary of the French firm, Société d'Etudes et de Montages, an international contractor specializing in industrial installations and hydraulic works across the world.  

The Company became a subsidiary of GEC Alstom Group when GEC Alstom acquired Société d'Etudes et de Montages in France in 1994 and the firm became GEC ALSTOM SDEM. In 1996 GEC ALSTOM decided to refocus on its hydraulics business and divested from the company leading to the spin off of SDEM Erectors Nigeria Limited as an independent company. 
SDEM Erectors Nigeria Limited (SDEM) is an energy, industrial and infrastructure construction company specializing in electro-mechanical services, civil and structural construction, steel fabrication, steel structures and industrial equipment erection, operations and maintenance of industrial and energy plants.
In 30 years of operating in Nigeria, SDEM has built some of the most complex industrial installations in Nigeria deploying its considerable local infrastructure and equipment inventory.