Hazardous energy is not limited to electricity. Machines and equipment may contain electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other forms of energy that can seriously injure or kill a worker if the energy is unexpectedly released.
Lockout/tagout procedures are used to control these energy sources during servicing and maintenance so equipment cannot unexpectedly start, move, pressurize, release stored energy, or otherwise endanger workers.
All workers could be exposed to the dangers of hazardous energy. Workers need to be familiar with when lockout/tagout is needed and what to do if they find it in use in the workplace.
Understanding Lockout/Tagout
Lockout/tagout is a set of procedures used to isolate machines and equipment from hazardous energy sources and prevent unexpected energization, startup, or release of stored energy while servicing or maintenance is being performed.
Lockout involves placing a lockout device on an energy-isolating device so the machine or equipment cannot be operated until the device is removed.
Tagout is the application of a label or tag placed near the lockout that alerts others to the lockout status of the equipment.
Locks provide physical control of the energy-isolating device, while tags provide an important warning to others. When lockout is required and the energy-isolating device is capable of being locked out, OSHA generally requires lockout rather than relying on a tag alone.
Lockout and Tagout should always be used together to maximize safety.
OSHA General Industry Standard 1910.147(a)(1)(i)[Logout/Tagout] This standard covers the servicing and maintenance of machines and equipment in which the unexpected energization or start up of the machines or equipment, or release of stored energy, could harm employees. This standard establishes minimum performance requirements for the control of such hazardous energy.
When Lockout/Tagout Is Needed
Lockout/tagout protects workers performing servicing and maintenance from unexpected startup or the release of hazardous energy. Depending on the equipment and the work being performed, hazardous energy control may be necessary during activities such as:
- Servicing
- Maintenance
- Cleaning or unjamming
- Lubrication
- Setting up or adjusting equipment
- Making repairs
- Inspecting or modifying equipment
- Changing tools or components
Workers should never assume that shutting off a machine with its normal operating controls makes the equipment safe to service. Hazardous energy must be properly isolated and controlled according to the applicable energy control procedure.
OSHA General Industry Standard 1910.147(a)(2)(i) This [lockout/tagout] standard applies to the control of energy during servicing and/or maintenance of machines and equipment. 1910.147(b) Servicing and/or maintenance. Workplace activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment. These activities include lubrication, cleaning or unjamming of machines or equipment and making adjustments or tool changes, where the employee may be exposed to the unexpected energization or startup of the equipment or release of hazardous energy.
OSHA Construction Standard 1926.702(j) No employee shall be permitted to perform maintenance or repair activity on equipment (such as compressors mixers, screens or pumps used for concrete and masonry construction activities) where the inadvertent operation of the equipment could occur and cause injury, unless all potentially hazardous energy sources have been locked out and tagged. Tags shall read Do Not Start or similar language to indicate that the equipment is not to be operated.
Types of Hazardous Energy
A machine may have more than one source of hazardous energy, and shutting off one source may leave other hazards behind. Workers authorized to perform lockout/tagout must identify and control all hazardous energy associated with the equipment.
Common forms of hazardous energy include:
- Electrical – electrical circuits, motors, capacitors, batteries, and other electrical sources
- Mechanical – moving or rotating parts, springs, flywheels, elevated components, or other stored mechanical energy
- Hydraulic – pressurized hydraulic fluid, cylinders, accumulators, and equipment that can move when pressure is released
- Pneumatic – compressed air or gas contained in lines, cylinders, compressors, or other pressurized systems
- Chemical – chemicals contained in pipes, tanks, vessels, or systems that may be pressurized or capable of an unexpected release
- Thermal – hot equipment, steam, heated materials, furnaces, refrigeration systems, or extremely cold materials
- Other energy sources – equipment or processes may involve additional hazards that must be identified and controlled before servicing begins
Stored or residual energy is particularly important. Even after equipment has been disconnected from its primary energy source, pressure, heat, gravity, springs, capacitors, moving parts, or other stored energy may remain.
Locks and Tags
Lockout devices are designed to hold an energy-isolating device in a safe or off position and prevent equipment from being energized. Depending on the equipment, lockout may involve locks, hasps, valve covers, breaker lockouts, chains, or other devices designed for the specific energy-isolating device.
Tags communicate that the machine or equipment is being serviced and must not be operated. Tags provide a warning, but unlike locks, they do not physically prevent someone from operating an energy-isolating device.
OSHA Construction Standard 1926.417 Controls that are to be deactivated during the course of work on energized or deenergized equipment or circuits shall be tagged. Equipment or circuits that are deenergized shall be rendered inoperative and shall have tags attached at all points where such equipment or circuits can be energized. Tags shall be placed to identify plainly the equipment or circuits being worked on.
Recognize Lockout/Tagout
All employees who work around equipment where lockout/tagout may be used should understand what locks, tags, and other energy control devices mean.
If equipment is locked or tagged out:
- Never attempt to start or operate the equipment.
- Never remove, bypass, alter, or tamper with a lock or tag.
- Never restore an energy source because the equipment appears ready to operate.
- Stay clear of equipment being serviced unless your work requires you to be there.
- Report damaged, missing, or questionable lockout/tagout devices to the appropriate supervisor or authorized employee.
Only employees who have received the appropriate training and authorization should perform lockout/tagout procedures.
Controlling Hazardous Energy
Effective lockout/tagout requires more than turning off equipment and attaching a lock. Authorized employees must follow the established energy control procedure for the machine or equipment. Depending on the equipment and procedure, this includes shutting down the equipment, isolating energy sources, applying lockout/tagout devices, controlling stored or residual energy, and verifying that isolation has been accomplished before servicing begins.
Employees affected by the shutdown must also understand the purpose of the lockout/tagout and know not to interfere with the devices or attempt to operate the equipment.
Lockout/Tagout Saves Lives
Hazardous energy may be invisible, stored, or capable of being released without warning. A machine that appears stopped or disconnected can still contain enough energy to cause crushing injuries, amputations, burns, electrocution, or other serious injuries.
Before servicing or maintenance begins, identify every hazardous energy source and follow the required energy control procedure. Never bypass, remove, or ignore a lockout or tagout device. Proper lockout/tagout keeps hazardous energy under control until the work is complete and the equipment can be safely returned to service.
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