By: Aaron Wissen

October 2012

Controlling hazardous energy sources is vitally important for those responsible for

servicing or maintaining machines or equipment. It should be obvious that certain

industrial equipment can be dangerous when used, but it can also present hazards

when not in operation. Serious physical harm or death could occur if the hazardous

energy is not properly controlled. As long as energy sources such as electricity,

hydraulic, pneumatic, mechanical, chemical, thermal, etc. are attached to a piece of

equipment or a machine…a potential hazard exists.


Lockout/Tagout simply refers to the series of procedures or specific practices designed

to safeguard employees from unexpected startup of the equipment or the release of

residual/stored energy within the device. So why utilize lockout/tagout?


It is estimated that there are 3 million workers who perform equipment maintenance

and these individuals face the greatest risk of injury if lockout/tagout is not

appropriately executed. About 120 fatalities and 50,000 injuries each year are

prevented from compliance with the lockout/tagout standard (29 CFR 1910.147).

Workers who are injured from exposure to hazardous energy lost an average of 24

workdays for recovery, and most were credited for having insufficient hazardous energy

control procedures, specifically lockout/tagout procedures.


When developing a lockout/tagout program, it is critical to be as specific as possible,

because vague language could lead to a potentially dangerous situation. The primary

aspect should focus on equipment isolating instructions. Spell out exactly what to do for

shutting down and restarting the equipment. Involve the operators and craftsmen as

well since they will have to most knowledge of the equipment’s features.

Once all proper procedures have been determined, all individuals need to be trained,

made aware of the hazards and the steps that have been taken to protect them. An

effective lockout/tagout program will have a set of instructions that will commonly



Preparation for Lockout/Tagout – Make sure to locate and identify all isolating devices

to be certain which switches, valves, or other energy isolating devices apply to the

equipment to be locked out and tagged. More than one energy source may be involved.


Lockout/Tagout Sequence - Each maintenance person working on equipment will have

his own lock and the only key to that lock for locking out equipment. The master key to

lockout locks is available only to maintenance supervisor and safety director. The

following steps will be taken to safely secure a listed machine for servicing and/or repair.

  • Notify all affected employees and supervisors that lockout/tagout is required.
  • The machine to be serviced/repaired will be shut off using the standard operator controls, i.e. off switch, trigger release.
  • Disconnect or isolate all energy sources. Some machines are of new construction and contain several safety interlocks. During work on gas, air, oil, acid, steam, and water lines the main valve will be closed and locked out. (Examples such as Release Tension, Release Compressed Air, Lower Hydraulics Bleed Gas Lines, Unplug Electrical Cords, Remove Spark Plugs, Bleed Hydraulics, Block Suspended Components, Block Rotating Parts, and Insert Blind Flange in Process Pipes)
  • Inspect the machine for any sources of stored energy. Make sure that nothing in or on the machine will cause any unexpected movement, which may cause any injury to those servicing the machine.
  • Lockout/Tagout all energy sources with company locks and tags. When a switching device is encountered that cannot be locked out, a proper tag may be used.
  • Each authorized employee involved in the work must lock and tag the main on/off switch. When three or more authorized employees are to work the same job, a lead employee may be appointed to perform the lockout/tagout and only the lead employee is then required to apply locks and tags.
  • Attempt to activate the machine by turning the operator switch to the on position. If the machine does not energize return the switch to the off position. If the machine does energize inspect it for the sources of energy and de-energize. Then repeat the attempt to reactivate the machine.
  • Once the operator control has been returned to the off position, release the machine as "LOCKED-OUT" and maintenance/repair efforts may proceed.

Lockout/Tagout Authorized Release Sequence - Utilize the following procedures for

returning a machine to service.

  • Inspect the machine to make sure that no tools, product or other parts have been left on the machine, which may cause a hazard when the machine is re-energized.
  • Inspect to make sure that if any operating safety guards have been removed during the servicing/repair process, they are replaced before the machine is energized.
  • Clear all employees from the area of the machine, particularly those areas close to or near any moving parts.
  • Check to make sure the operator controls are in the off position.
  • Remove the lockout security device and re-energize the machine.
  • Activate the machine by moving the operator switch to the on position and observing the operation of the machine.
  • Switch off the machine and ensure that it ceases operation.
  • Notify the affected employee that the machine is available for use.

Conduct periodic audits of the program from time to time to ensure that the procedures

up-to-date, as your program/procedures need to reflect any changes to the system. A

well visualized and monitored lockout/tagout program will help keep both the employees

safe and ensure proper shutdowns and restarts that will protect the equipment.