Workforce
Night Shifts and Fatigue in a Shutdown: Hours and Rest Limits
Treat night work as a controlled risk with written limits. HSE guidance suggests capping shifts at 12 hours including overtime, limiting long night shifts to 2 or 3 in a row, and keeping demanding or safety-critical work out of low-alertness hours. API RP 755 sets outage ceilings of 14 hours a shift and 182 hours per work-set, with a documented exception process. Record actual hours daily.
How MaintWiz helps: The MaintWiz shutdown module carries this work as work packages with checklists, readings and photos, permits and readiness gates, so the result stays with the work order.
By Jai Balachandran · Technical review: Murali Nerur Pasupathy · Published · Last reviewed
What MaintWiz adds:Critical path and floatReadiness gatesPermits and isolationsChecklists with readings
Published limits
What hour and rest limits do the published sources set?
HSE gives guidance; API RP 755 is a recommended practice for refining and petrochemical process-safety roles, and neither is a fixed legal cap.
| Source | Control | Published value |
|---|---|---|
| HSE HSG256 (2006) | Maximum shift length | 12 hours including overtime; 8 hours for night or safety-critical, demanding work |
| HSE HSG256 (2006) | Consecutive shifts | 5 to 7 days for standard shifts; 2 to 3 for long, night or early-start shifts |
| HSE HSG256 (2006) | Day-to-night changeover | Minimum 2 nights' full sleep |
| UK Working Time Regulations (as stated in HSG256) | Daily rest | 11 consecutive hours |
| API RP 755, 2nd edition (2019), normal operations | Hours cap | 14 hours per shift and 92 per work-set (105 for straight days); 34 hours off, or 46 if the set had 4 or more nights |
| API RP 755, 2nd edition (2019), outages | Hours cap | 14 hours per shift and 182 per work-set; 34 hours off after the work-set |
Planning
How should the shutdown plan handle night shifts and fatigue?
HSE names plant shutdown as a pressure that pushes people to work extended hours, so the limits belong in the plan before the stop starts.
- Write the hour limits into the shutdown plan and the contractor requirements: maximum shift length, consecutive shifts, minimum rest.
- Avoid permanent night shifts and allow at least 2 nights of full sleep when crews switch between days and nights.
- Keep demanding, dangerous or safety-critical work out of the low-alertness hours and the end of long shifts.
- In refining and petrochemical process-safety roles, apply API RP 755: on-site contractors in those roles need equivalent fatigue risk controls.
- Define an exception process for hours above the limit: a documented risk assessment, a mitigation plan, and approval by the supervisor and another manager.
- Record actual hours worked each day, including overtime and contractor crews, and review them at the daily meeting.
FAQ
Frequently asked questions
Is there a legal maximum number of consecutive night shifts for a shutdown?
HSE's guidance is advice rather than a fixed legal cap: it suggests limiting long or night shifts to 2 or 3 in a row. The Working Time Regulations set 11 hours' daily rest. API RP 755 is a recommended practice, not law.
Do API RP 755 limits apply to contractors during a turnaround?
Yes for contractors in process-safety-sensitive roles: the API fact sheet says on-site contractors in those roles must have fatigue risk management equivalent to its criteria.
How long should crews rest after a block of shutdown shifts under API RP 755?
A work-set is complete after 34 hours off, or 46 hours off in normal operations if it included 4 or more night shifts. For outages the fact sheet lists 34 hours.
What should a shutdown plan do when hours must exceed the limit?
API RP 755 describes an exception process with a documented risk assessment and mitigation plan, with supervisor and management involvement.
Sources
Sources
UK HSE guidance, the API RP 755 fact sheet and OSHA pages read on 30 October 2026; the paid RP 755 standard itself was not read.
Plan this work in the shutdown module
Book a demo and bring your next shutdown scope. We will show how the work, the permits and the results sit in one plan.