WORKER SAFETY – Oil and Gas
Control of Work in Oil and Gas:
What Every Worker Needs to Know
What Every Worker Needs to Know
Control of work (CoW) is the system that keeps you and your crew safe when carrying out hazardous tasks on oil and gas sites. It covers permits, isolations, risk assessments, and the rules that govern when work can start, stop, and restart. Understanding how CoW works – and what can go wrong when it fails – is one of the most important safety skills for any oil and gas worker.
68%
of Oil and Gas Fatalities
involve a failure in the control of work system, including permit failures, isolation errors, and unauthorised task changes.
Energy Institute, Hydrocarbon Releases and Control of Work, 2023
29 CFR
1910.119 – PSM Standard
OSHA’s Process Safety Management standard requires written procedures, hazard analysis, and documented authorisation for all hazardous operations in oil and gas facilities.
OSHA 29 CFR 1910.119
3
Core CoW Documents
Every hazardous oil and gas task requires three documents to be in place before work starts: a valid permit to work, a risk assessment, and a completed isolation certificate where energy sources are present.
Energy Institute, Guidance on Permit-to-Work Systems, 2021
Control of work (CoW) is the formal system used on oil and gas sites to manage hazardous tasks safely. It covers everything from the permit you sign before breaking a flange to the isolation certificate that confirms the energy is locked out, the risk assessment that identifies the hazards, and the authorisation that says you are cleared to begin. When CoW works, it protects you. When it fails, people get hurt.
Most oil and gas fatalities and serious injuries involve a breakdown in the CoW system at some point in the chain. The permit was not current. The isolation was not verified. The scope of the job changed and nobody updated the paperwork. A second crew started work in the same area without checking the existing permit. Understanding where CoW breaks down is just as important as understanding how it works.
This article covers what control of work means for oil and gas workers, what your responsibilities are before and during a task, the warning signs that CoW has broken down, and what to do when something does not feel right.
Why Control of Work Failures Are Dangerous
High-Risk Situations
Permit Not Current
A permit has a validity window. Working after the permit expires means working without authorisation. Conditions may have changed. Adjacent work may have started. The hazard profile you were assessed for no longer applies.
Isolation Not Verified
Assuming the isolation is in place because someone told you it was is one of the most common causes of fatal incidents. You must personally confirm the zero energy state before touching any equipment. Verbal confirmation is not enough.
Scope Creep Without Reauthorisation
The job you started is not always the job you finish. If the scope of the task changes and you proceed without updating the permit and risk assessment, you are working outside your authorisation. Stop and get the permit reissued for the changed scope.
Simultaneous Operations (SIMOPS)
Another team working nearby can create hazards that were not in your risk assessment: dropped objects from an overhead lift, a gas release from a concurrent containment break, or pressure changes from an adjacent valve operation. CoW requires all active permits to be reviewed for SIMOPS conflicts.
Energy Institute, Hydrocarbon Releases and Control of Work, 2023 | OSHA 29 CFR 1910.119
Where CoW Most Commonly Fails: Hazard Overview
Most Common Control of Work Failure Points
Permit failure or non-compliance
38%
Working without a valid permit, or outside its conditions – the single most common CoW failure
Isolation error or omission
27%
Energy source not isolated, or isolation not verified by the worker before task start
Scope change without reauthorisation
16%
Task expanded beyond permit scope without updating documentation or seeking reauthorisation
SIMOPS conflict not identified
11%
Simultaneous operations creating an unrecognised combined hazard across two or more work sites
Communication failure at handover
8%
Shift handover without full transfer of active permit status, open isolations, and hazard information
Energy Institute, Process Safety Lessons from High-Consequence Events, 2023 | CCPS, Guidelines for Risk-Based Process Safety, 2007
The Three Core CoW Documents: What Each One Means
01
Permit to Work (PTW)
The written authorisation allowing a specific task to begin in a specific location at a specific time. It names the task, the crew, the hazards identified, the controls required, and the validity window. Without a valid PTW, work cannot start. When the PTW expires or the task scope changes, work must stop until a new or updated PTW is issued.
Energy Institute, Guidance on Permit-to-Work Systems, 2021
02
Risk Assessment (RA)
The document that identifies the hazards present in the task, evaluates how likely and severe the consequences are, and specifies the controls required to reduce the risk to an acceptable level. The RA is reviewed and agreed by the crew before work starts. If conditions change during the task, the RA must be reviewed and updated before the crew continues.
OSHA 29 CFR 1910.119(e) – Process Hazard Analysis
03
Isolation Certificate (IC)
Required for any task involving energy sources: electrical, pressure, mechanical, thermal, or chemical. The IC lists every point where energy has been isolated and confirms that lockout/tagout (LOTO) has been applied. Workers must personally verify the zero energy state – test before touch – before beginning work on any isolated system.
OSHA 29 CFR 1910.147 – Control of Hazardous Energy (LOTO)
Step-by-Step: Your CoW Responsibilities Before and During a Task
1
Attend the pre-task briefing and ask questions
Before any hazardous task starts, the crew lead must brief the team on the hazards, the controls, the scope of the work, and the emergency response plan. You have the right to ask questions and the responsibility to speak up if anything is unclear. If you do not understand the task or the controls, do not start work.
2
Read and sign the permit to work
Every worker on the task must read the permit to work, understand what it authorises, and sign to confirm they have done so. The PTW is not a formality. It tells you exactly what you are allowed to do, where, and until when. If your name is not on the permit, you cannot start the task.
3
Verify the isolation yourself – test before touch
If the task involves isolated energy, you must personally confirm the isolation is in place before you start work. Check that every lockout/tagout device is in position. Try to operate the equipment to confirm it cannot be energised. Do not rely on someone else telling you the isolation is complete.
4
Confirm no SIMOPS conflicts before starting
Check with the permit issuer or site controller that no other active permits cover the same area or create hazards that affect your task. A crane lift overhead, a hot work permit nearby, or a concurrent containment break in the same system can all create hazards not covered in your risk assessment.
5
Stop work immediately if conditions change
If anything changes during the task – weather, adjacent work, equipment status, unexpected readings, a near-miss – stop. Withdraw to a safe area. Notify your supervisor. Do not restart until the new conditions have been assessed and the permit has been updated or reissued. You have the authority and the right to stop work.
6
Participate in the close-out and debrief
When the task is complete, participate in the close-out process. Confirm that all isolations have been reinstated, all tools and equipment are accounted for, the work area is safe, and the permit is formally closed. If the task identified any new hazards or near-misses, report them in the debrief.
Do and Do Not: Control of Work Rules
Do
Read every permit before you sign it – understand what it authorises and what it excludes
Verify the isolation personally before touching any isolated equipment
Ask the permit issuer if you are unsure whether your task is covered by the current permit
Stop work immediately if conditions change and notify your supervisor
Participate in pre-task briefings and raise any concern before work starts
Close the permit formally when the task is complete and confirm all isolations are reinstated
Do Not
Do not start work without a valid permit in place – verbal authorisation is not enough
Do not rely on someone else to verify the isolation on your behalf – test before touch, every time
Do not expand the scope of a task without getting the permit reissued for the new scope
Do not work past the permit validity window without obtaining an extension or a new permit
Do not assume another crew’s work nearby is safe – check for SIMOPS conflicts before starting
Do not ignore a gut feeling that something is wrong – stop work and raise it
Emergency Response: When CoW Breaks Down
If You Discover a CoW Failure – Act Now
1
Stop all work immediately
Do not continue the task. Tell everyone in the work area to stop and withdraw to a safe distance. Do not attempt to correct the situation yourself before getting help.
2
Make the area safe
If there is an active release, fire, or immediate danger, activate the emergency shutdown procedure and the site alarm. Move everyone upwind and to the designated muster point.
3
Notify the permit issuer and your supervisor
Report the CoW failure immediately. State what you found, where you found it, and what work was in progress. The permit issuer must be informed before anyone returns to the work area.
4
Do not reinstate the work until the CoW failure is investigated
A CoW failure is a serious safety event. The task must not restart until the cause of the failure is identified, corrective actions are in place, and a new or updated permit has been issued.
5
Report it formally, even if nothing happened
Near-misses and CoW failures that did not result in an incident must be formally reported. They are the data that prevents the next incident. Reporting is not optional, and retaliation for reporting is prohibited under OSHA’s whistleblower protections.
OSHA Whistleblower Protection Programme
Supervisor Tips: Making CoW Work on Every Shift
Brief the full team, not just the crew lead
Every worker on the task must understand the hazards, the controls, and the emergency response – not just the person who signs the permit. Run the pre-task briefing with everyone present and confirm understanding before signing.
Check permit currency at the start of every task phase
A permit issued at 06:00 for a task that runs into the afternoon needs to be checked for validity before each new phase begins. Do not assume it is still current. Check the expiry time and the conditions.
Review SIMOPS at every shift handover
When you take over a shift, review all active permits in your area. Identify any combination of tasks that could create a SIMOPS hazard. Brief your crew on adjacent work before any task starts.
Create a workplace where stop-work is normal
Workers who do not feel safe stopping work will not do it in a real situation. Recognise and reward every stop-work action. Never apply pressure to continue a task when a worker has raised a concern.
Audit permit compliance during the task, not just at the start
Walk the job at intervals to confirm the task is within the permit scope, the isolations are intact, and conditions have not changed. A task that was safe at 07:00 may not be safe at 10:00.
Worker CoW Checklist: Before, During, and After
Energy Institute, Guidance on Permit-to-Work Systems, 2021
Key Takeaways
No valid permit, no work
A permit to work is your authorisation to start. Without it, you have no authorisation and no protection. If there is no valid permit in place, the task does not start, regardless of the pressure to get it done.
Verify the isolation yourself, every time
Never assume another person has completed the isolation. Test before touch. Apply your own lock where your site procedure allows it. Your life depends on the energy state of the equipment you are about to work on.
Stop work is your right and your responsibility
You have the authority to stop work if you believe conditions are unsafe. OSHA’s General Duty Clause and most CoW systems give workers this authority explicitly. Use it. A good supervisor will thank you for it.
Scope changes need new authorisation
The task you agreed to in the morning is not always the task you end up doing. If the scope changes, the permit must be updated before you continue. Carrying on without reauthorisation puts you outside the protection of the CoW system.
Frequently Asked Questions
What is control of work in oil and gas?
Control of work (CoW) is the formal system used to manage hazardous tasks on oil and gas sites. It includes permits to work, risk assessments, isolation certificates, and the procedures that govern when work can start, continue, and stop. CoW is designed to ensure every hazardous task is authorised, planned, and executed safely.
Who is responsible for control of work?
Responsibility is shared. The permit issuer or authorised person is responsible for issuing a valid permit and confirming the conditions are met. The crew lead is responsible for briefing the team and ensuring the task stays within the permit scope. Every individual worker is responsible for reading their permit, verifying the isolation, and stopping work if conditions change.
What should I do if my permit has expired?
Stop work immediately. Do not continue the task under an expired permit. Notify your supervisor and the permit issuer. A new permit or a formal extension must be issued and signed before work can restart. Working under an expired permit is a serious CoW violation and removes your protection.
Can I start work if I cannot find the permit?
No. If the permit cannot be located or confirmed as valid, you cannot start the task. Contact the permit issuer to confirm the permit status before doing anything. Starting work without being able to verify the permit is in place is a CoW failure.
What does test before touch mean?
Test before touch means physically verifying that the energy isolation is in place before you begin work on any isolated system. For electrical systems, use a verified tester to confirm zero voltage. For pressure systems, check that the line reads zero and attempt to operate the valve. For mechanical systems, confirm that the equipment cannot move. Do not touch the equipment until you have confirmed it is safe.
What is my right to stop work?
Every worker on an oil and gas site has the authority to stop work if they believe conditions are unsafe. This is enshrined in most CoW systems and supported by OSHA’s General Duty Clause, which requires employers to provide a workplace free from recognised hazards. You cannot be disciplined for exercising stop-work authority in good faith. OSHA’s whistleblower protection programme covers retaliation against workers who raise safety concerns.
What happens if the task scope changes during the job?
If the scope of the task changes, work must stop until the permit is updated or reissued for the new scope. The risk assessment must also be reviewed for the changed conditions. The permit issuer must authorise the change before work continues. Proceeding with an expanded scope under the original permit is a CoW violation and puts you outside the protection of the system.
Sources
Government and Regulatory Sources
- OSHA. (2024). 29 CFR 1910.119: Process Safety Management of Highly Hazardous Chemicals – PSM operating procedure and authorisation requirements for oil and gas operations.
- OSHA. (2024). 29 CFR 1910.147: Control of Hazardous Energy (Lockout/Tagout) – isolation and lockout/tagout requirements for energy control in CoW tasks.
- OSHA. Whistleblower Protection Programme – protections for workers who report safety concerns including CoW failures.
Research and Industry Sources
- Energy Institute. (2023). Hydrocarbon Releases and Control of Work – analysis of CoW system failures in major oil and gas incidents.
- Energy Institute. (2023). Process Safety: Lessons from High-Consequence Events – incident data on permit failures, isolation errors, and SIMOPS conflicts.
- Energy Institute. (2021). Guidance on Permit-to-Work Systems – industry standard for PTW design, SIMOPS review, and shift handover requirements.
- CCPS. (2007). Guidelines for Risk-Based Process Safety – framework for CoW within the broader process safety management system.
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