DÜVs (short for Dampfkessel Überwachungs-Verein, Steam Boiler Inspectorate Organization in English) were German organizations founded in the 19th century by a group of German entrepreneurs to ensure the technical safety of steam boilers, which was an immanent issue at that time.
The charter of the organizations stated they were founded "to prevent steam boiler explosions through regular, periodical inspections... to foster the implementation of all current and future improvements (regarding economic efficiency of the whole machine as well as energy efficiency of the fire engine) in the operation of steam boilers so that all members of the organization can benefit."
DÜVs were the predecessor of TÜVs.
References
Dampfkessel Überwachungsverein Wikipedia(Text) CC BY-SA