A permit-to-work system is a formal written system used to control certain types of work that are potentially very hazardous. The permit-to-work specifies the work to be done and the precautions to be taken. Permits to work form an essential part of safe systems of work for particularly hazardous maintenance activities. They allow work to start only after the hazards have been considered and eliminated or controlled by identifying and defining safe procedures that will not create additional hazards. The system also provides a record that the hazards and risks have been systematically considered and eliminated. To be effective a permit-to-work system has to be carefully and closely managed. In operation it is only as good as the management effort put into it.
- Examples of hazards and activities that might require the use of a formal permit-to-work system include:entry into closed vessels and confined spaces.
- breaking into pipelines that contain flammable or hazardous substances.
- hot work on plant that has contained flammable or hazardous substances.
- work on electrical distribution systems and high voltage installations.
- complex automated machinery where action or adjustment of one part of the machine may produce an action some distance away or where there may be stored hydraulic, pneumatic or mechanical energy systems.