[en] The safety of people and the environment is increasingly important in the operation and, consequently, also in the project design of process equipment. Rules and regulations for safeguarding of industrial process plants (not-nuclear and nuclear) by means of process control engineering are either being developed or expanded. This includes the international harmonization of existing national codes. This article presents an introduction into the philosophy of ensuring plant safety by means of instrumentation and control protection systems. The methods of risk assessment are described, and various potential solutions are shown which are geared to achieving the necessary level of safety and, at the same time, allowing flexible operation to be maintained. Reference is made to the problems existing with respect to integrating people into this process, i.e. man-machine interaction, especially in view of possible interventions in emergencies