Maintenance: a moment of heightened risk
Working on a piece of equipment usually means taking it out of its normal operating state: opening a housing, removing a guard, reaching parts that are normally out of reach. That is exactly what makes maintenance dangerous. A machine that has stopped is not necessarily a safe machine. It can still hold energy capable of injuring or even killing someone if it restarts or releases at the wrong moment.
These hazardous energies come in several forms:
- Electrical: live voltage, charged capacitors, automatic restart.
- Mechanical: moving parts, flywheels, compressed springs, suspended loads.
- Pneumatic: compressed air stored in tanks or cylinders.
- Hydraulic: pressurised fluids that can spray or set parts in motion.
- Thermal: hot surfaces, steam, heat-transfer fluids.
- Chemical: corrosive, toxic or flammable products, residues left in piping.
The danger rarely comes from a single source. One piece of equipment can combine several energies, and a poorly prepared intervention exposes the technician to an unexpected restart or to a release of residual energy.
The principle of lockout-tagout (LOTO)
Lockout-Tagout (LOTO) is the reference method for neutralising these energies before any work begins. The goal is simple: make sure the machine cannot restart or release energy while someone is working on it. The approach follows an ordered sequence.
- Identify every energy source on the equipment. This is the most frequently underestimated step: you need to know the machine, its diagrams and its secondary circuits.
- Isolate the equipment from its sources: cut the electrical supply, close the valves, isolate the circuits.
- Lock and tag the isolation devices in the safe position, using individual padlocks. Each worker applies their own lock: as long as one lock remains in place, re-energising is impossible.
- Verify the absence of energy: measure that there is no voltage, bleed off pressure, dissipate residual energy (discharge a capacitor, block a mass, let surfaces cool). A no-load start attempt confirms the equipment is genuinely neutralised.
- Remove the lockout at the end of the job, in reverse order and in a controlled way: make sure no one is in the danger zone, remove the locks, then restore energy.
Tagging goes hand in hand with locking: a tag states who applied the lockout, when, and why. It forbids any operation by a third party.
Procedures and checklists: turning know-how into reliable actions
Lockout relies on precise actions, in a precise order. Leaving that to memory or habit opens the door to omissions — especially under pressure or during an emergency job. This is where procedures and checklists come in.
A good safety procedure describes, for a given piece of equipment, the energy sources to neutralise, the isolation points, the verifications to carry out and the protective equipment required. The checklist forces the worker to tick off each critical step: “voltage verified at zero”, “pressure bled”, “lock applied”. Making certain steps mandatory prevents moving on until the safety point has been validated.
The benefit is twofold: it makes the action reliable for the experienced technician, and it guides the less experienced one step by step.
The work permit
For high-risk interventions — work at height, confined space, hot work (welding, grinding), work on shared equipment — the procedure alone is not enough. A work permit formalises the authorisation to intervene: it states the nature of the work, the risks, the preventive measures, the authorised people and the period of validity. It requires sign-off by a supervisor before the job starts and an explicit closure at the end.
The work permit imposes a moment of pause and reflection before acting. That moment is often what prevents the accident.
Traceability and training
Two pillars complete the system.
- Traceability: knowing who applied the lockout, who worked on the equipment, which steps were validated and when. In the event of an incident, this record is essential. Day to day, it builds accountability and makes it possible to analyse deviations.
- Training: lockout cannot be improvised. Workers must be trained on the energies of their equipment, certified where regulations require it, and regularly reminded of the risks. A procedure is only worth something if the person applying it understands why it exists.
Where a CMMS like Maint Vision can help
A CMMS does not replace safety devices. Padlocks, tags, voltage testers and permits remain physical and organisational safeguards that nothing can replace. Maint Vision is not a certified lockout or work-permit system, nor a dedicated EHS software.
What a CMMS does help with is documenting and tracing everything around the intervention. With Maint Vision, you can attach safety procedures and checklists, along with work orders, directly to equipment and interventions, make certain steps required so they are not skipped, and keep a record of who did what and when. These procedures recall the lockout points specific to each machine and keep the intervention history in one place.
Used this way, the CMMS becomes a support for the safety culture: it does not perform the action for you, but it helps make sure nothing is forgotten, structures good practice and preserves a memory of interventions. Safety remains a matter of people, their training and their rigour — the tool is there to support them.