What Is a Permit to Work System? A Practical Guide for Oil & Gas Contractors
How permit to work systems control hazardous work on oil and gas sites, where paper systems break down, and what changes when permits go digital.
Why permit to work systems exist
Many serious accidents in the process industries happen during maintenance and other non-routine work, when the normal operating controls of a plant do not apply. A permit to work system exists to make sure that everyone involved knows exactly what work is happening, where, what hazards it creates, and which safeguards must be in place before it starts.
The Piper Alpha disaster in 1988 made this painfully clear. A pump was restarted while one of its pressure safety valves had been removed for maintenance, and the public inquiry that followed found serious failings in how permits were managed and communicated at shift handover. 167 people died. Since then, permit to work has been treated as a core part of safety management across the oil and gas industry.
Regulators and operators set expectations for how it is done. The UK Health and Safety Executive publishes guidance on permit-to-work systems (HSG250), and operators such as Saudi Aramco, ADNOC, and PDO specify their own permit requirements for the contractors who work on their facilities.
What work needs a permit
Each site defines its own list in its permit to work procedure, but most oil and gas facilities require a permit for work such as:
- Hot work — welding, cutting, grinding, or any source of ignition near flammable materials.
- Confined space entry — vessels, tanks, pits, and other enclosed spaces.
- Work at height.
- Electrical work and the isolation of electrical equipment.
- Excavation and ground disturbance.
- Breaking containment on process equipment and pipework.
- Critical lifting operations and radiography.
The permit lifecycle, step by step
Every permit follows a lifecycle. The names differ between companies, but the logic is the same: nothing starts until controls are verified, and nothing is closed until the area is safe to return to operation.
| Step | What happens |
|---|---|
| 1. Request | The team doing the work describes the job, location, equipment, and expected duration. |
| 2. Risk assessment | A job safety analysis or task risk assessment identifies hazards and the controls needed. |
| 3. Isolation | Energy sources are isolated and locked, usually recorded on an isolation certificate. |
| 4. Gas testing | The atmosphere is tested where required and results are recorded, with re-testing at set intervals. |
| 5. Authorisation | The responsible authority checks the controls and issues the permit with any conditions. |
| 6. Work and monitoring | The permit is displayed at the worksite and its conditions are checked during the job. |
| 7. Suspension and handover | Unfinished work is suspended or formally handed over between shifts. |
| 8. Completion and hand-back | The site is inspected, isolations are removed, and the area is returned to operations before the permit closes. |
Key roles in a permit to work system
Titles vary between companies, but most systems separate these responsibilities:
- Issuing or area authority — responsible for the plant area and authorises work in it.
- Performing authority or permit receiver — leads the work party and accepts responsibility for working within the permit conditions.
- Isolating authority — carries out and verifies isolations.
- Authorised gas tester — tests the atmosphere and records the results.
- Control room or site controller — keeps an overview of all active permits and conflicting activities.
Where paper permit systems break down
Paper permits can work, but they depend heavily on discipline and memory. The same weaknesses appear again and again in incident investigations and audits:
- No live view of every active permit, so conflicting work in the same area is easy to miss.
- Isolations that are not clearly cross-referenced to the permits that depend on them.
- Gas test results that are not recorded at the required intervals.
- Shift handovers done verbally, with details lost between crews.
- Permits left open after work finishes, or closed without a proper site inspection.
- Audits that take days because evidence is spread across folders and handwriting.
What changes with a digital permit to work system
A digital permit to work system (often called ePTW) does not replace the procedure or the site walk. It enforces the steps, stops permits progressing until required checks are complete, and records the evidence automatically.
| Area | Paper permits | Digital permits |
|---|---|---|
| Visibility | Permit board in one control room | Live view of all permits on any authorised screen |
| Conflicting work | Relies on people noticing | Automatic warnings for overlapping work on the same area or equipment |
| Isolations | Separate paper certificates | Linked to the permits that depend on them |
| Gas tests | Written on the form, if remembered | Timestamped entries with re-test reminders |
| Competency | Assumed | Only trained, authorised people can issue or receive permits |
| Audit | Days of document gathering | Complete history exported in minutes |
Off-the-shelf or custom permit to work software?
Off-the-shelf permit software suits organisations whose procedures match the product. Custom software makes sense when your permit types, approval chains, or client-specific formats are unusual — for example a contractor working for several operators with different requirements — or when you need offline mobile apps, Arabic interfaces, or integration with maintenance systems such as SAP or Maximo.
A custom digital permit to work system for one site typically costs $6,000–12,000 to build with an India-based team, and a pilot usually goes live in 8–12 weeks.
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