GE Hydro
GE Hydro uses Coin3D in software used for the design, analysis and manufacture of Hydro Turbines.
Screenshot and information provided by Nigel Murry.
Most of that software is very specialised and is used in-house by a small group of engineers engaged in developing more efficient blading. The above snapshot is from a blade inspection package that is used world-wide by their supplying foundries. You might recognize the Coin SoQt viewer used.