Guide
Permit to Work Guide: Permit-to-Work System
A permit-to-work (PTW) system controls high-risk maintenance activities by ensuring hazards are identified and controls are in place before work begins. Learn the types of permits and how to implement a PTW system.
8 min readUpdated July 2026
What is a Permit to Work?
A permit to work (PTW) is a formal, documented system that controls specific high-risk activities by requiring written authorisation before work begins. The permit ensures that hazards are identified, controls are implemented, the work is authorised by a responsible person, and the area is made safe before and after the work.
Types of Permits
| Permit Type | When Required |
|---|---|
| Hot work permit | Welding, cutting, grinding, soldering — any work that generates heat or sparks |
| Confined space permit | Entry into any space with restricted access/egress and potential for hazardous atmosphere |
| Cold work permit | Maintenance on live process equipment without heat sources |
| Excavation permit | Digging that may encounter underground services (pipes, cables) |
| Electrical permit | Work on or near live electrical equipment above 50V |
| Height permit | Work above 2 metres without fixed fall protection |
| Isolation permit | Isolation of energy sources (electrical, pneumatic, hydraulic) for maintenance |
| Radiation permit | Work involving radioactive sources or X-ray equipment |
Permit Process
- Identify the work: Determine what work is needed and whether a permit is required based on the risk assessment.
- Assess the hazards: Identify all hazards — energy sources, hazardous substances, confined spaces, fire risks.
- Specify controls: Determine the controls needed — isolation, ventilation, gas testing, PPE, fire watch, standby person.
- Complete the permit: Fill out the permit form — work description, location, hazards, controls, duration, personnel involved.
- Authorise: The permit is reviewed and signed by an authorised person (typically a supervisor or permit issuer) who verifies the controls are in place.
- Communicate: Brief all workers on the permit contents — hazards, controls, emergency procedures.
- Execute: Workers perform the work following the permit conditions. Any deviation requires a new permit.
- Close out: When the work is complete, the permit is signed off by the permit issuer. Verify the area is safe, all isolations are removed, and the area is returned to normal operation.
Key Rules
- One permit, one job — a permit covers a specific task, not multiple unrelated activities
- Permits have a time limit — typically one shift (8–12 hours). If work extends, a new permit is required.
- Permits must be displayed at the worksite — not filed in an office
- The permit issuer must be different from the person doing the work — separation of duties
- Gas testing must be current — confined space and hot work permits require gas testing before entry and periodically during work
- Emergency procedures must be defined — what to do if something goes wrong
- Permits must be closed out — an open permit means the area may still be isolated or hazardous
Critical
A permit to work is not a substitute for isolation (LOTO). The permit authorises the work; isolation makes the equipment safe. Both are required for high-risk maintenance.