What is lockout/tagout?

Lockout/tagout is the practice of isolating a machine from every source of hazardous energy and securing each isolating device with a lock and a tag, so the equipment cannot be started while somebody is servicing it. In the United States it is governed by OSHA 29 CFR 1910.147, The Control of Hazardous Energy.

What counts as hazardous energy?

More than electricity. Stored and residual energy counts too: hydraulic and pneumatic pressure, steam and other thermal energy, chemical systems, water and gas lines, springs and other mechanical stores, and gravity acting on a raised part. A machine is only de-energized when every one of its energy sources has been isolated, and each source usually needs its own isolation step.

Does every machine need its own written procedure?

Generally yes. OSHA 1910.147(c)(4) requires documented, machine-specific energy control procedures that name the isolating devices and the steps for shutting down, isolating, blocking, securing, and verifying. A narrow exemption exists for equipment with a single energy source that is fully de-energized and controlled by one isolating device under the lock of the person doing the work, with no stored energy and no re-accumulation.

How often must lockout procedures be inspected?

At least annually. OSHA 1910.147(c)(6) requires a periodic inspection of each energy control procedure, performed by an authorized employee who is not using the procedure being inspected, with the inspection certified in writing.

What is group lockout?

When a crew services one machine together, OSHA 1910.147(f)(3) requires protection equivalent to a personal lockout for each worker. In practice each authorized employee applies their own lock, often to a group lockout device or hasp, and the machine is not released until every one of those locks has been removed by the person who applied it.

Who is allowed to remove a lock?

The employee who applied it. OSHA 1910.147(e)(3) allows removal by somebody else only under a documented procedure that includes verifying the employee is not at the facility, making all reasonable efforts to contact them, and ensuring they know the lock has been removed before they resume work.

Lockout/Tagout Basics: OSHA 1910.147 Energy Control

Lockout/tagout (LOTO) is how a machine is made safe to work on: every source of hazardous energy is isolated, and each isolating device is secured with a lock and a tag so the equipment cannot be started while somebody is inside it. In the United States the governing rule is OSHA 29 CFR 1910.147, The Control of Hazardous Energy. It applies to servicing and maintenance, not to normal production operation.

What an energy control program requires

Written, machine-specific procedures - documented steps that name the isolating devices for that equipment and cover shutdown, isolation, blocking, securing, and verification.
Locks and tags - durable, standardized, identifying who applied them, and not used for any other purpose.
Training - authorized employees who apply locks, affected employees who operate the equipment, and other employees who work in the area each need training suited to their role.
Annual periodic inspection - each procedure inspected at least yearly by an authorized employee not using it, and certified in writing.

Hazardous energy is not only electrical

A machine is de-energized only when every source is isolated, and each source generally needs its own isolation step and its own verification:

Electrical - supply disconnects and control power.
Hydraulic - pressure held in cylinders and accumulators.
Pneumatic - compressed air, including stored receiver pressure.
Mechanical - flywheels, springs, and moving parts that coast.
Thermal - hot surfaces, steam, and residual heat.
Chemical - process lines carrying hazardous substances.
Water and gas - supply lines under pressure.
Gravity - raised rams, platforms, and loads that can fall.

The six steps of applying a lockout

Prepare - identify every energy source and the isolating device for each.
Notify - tell affected employees the equipment is coming out of service.
Shut down - stop the equipment by its normal stopping procedure.
Isolate - operate each isolating device to cut the equipment off from its energy.
Lock and tag - apply a lock and tag to each isolating device.
Release stored energy and verify - bleed, block, or restrain anything stored or residual, then test that the equipment cannot start.

Restoring the equipment reverses it: check the work area, confirm everyone is clear, remove each lock, and notify affected employees before re-energizing.

Frequently asked questions

Is a tag alone ever enough?

Only where an isolating device cannot accept a lock. A tagout-only program must provide protection equivalent to lockout, and the tag has to be attached where the lock would have gone. Where a device is capable of being locked out, it must be.

What about a crew working on one machine?

Each authorized employee gets protection equivalent to a personal lockout, normally by applying their own lock to a group lockout device. The machine stays locked out until every one of those locks has come off, and each is removed by the person who applied it.

Who removes a lock if that person has gone home?

Only under a documented procedure: verify the employee is not at the facility, make all reasonable efforts to reach them, and make sure they know the lock was removed before they return to work.

About Bowvue - Bowvue keeps machine-specific lockout/tagout procedures with the equipment they belong to, prints a separate sheet per energy type with its isolation steps, PPE, and restoring-to-service steps in English or Spanish, and puts a QR code on each sheet that opens that machine's procedures on a phone.