Glossary · Safe work, maintenance and competence
Permit to work
Also known as: PTW, work permit
In occupational safety, a permit to work is a formal authorization process for defined hazardous work under specified controls. It records what work is done, where, by whom, which hazards and controls apply, and when the equipment is handed back.
- Machine safety
- Maintenance
- Human factors
In one sentence
A permit to work formally authorizes defined hazardous work under stated controls, and it closes with a handback before restart.
Example
Welding inside a hopper of a production line needs a permit to work combining confined space entry, hot work and lockout; the permit is issued by the area supervisor and closed only after the hopper is cleared.
How it applies
- Machine safety: Permits are used for non-routine work where a standard procedure is not enough: hot work, confined spaces, work near live parts or on integrated lines. They often refer to lockout/tagout rather than replace it.
- Human factors: A permit works only if the issuer checks the site. Signing forms without looking is a known failure mode.
- Integrated systems: Permits coordinate work across areas. Conflicting permits in the same area are a SIMOPS issue and need a cross-check.
- Evidence: The permit and its closure form an audit trail of who authorized what, and when control of the equipment returned to operations.
Permit to work vs. job hazard analysis
A job hazard analysis identifies the hazards and controls of a task. The permit authorizes the task at a given time and place and confirms that the controls are in place.