To learn, understand, and follow procedures necessary to disable equipment and machinery during service and maintenance.
Employees who operate equipment being serviced under lockout or tagout procedures (authorized employees) or who work in an area where the service activity occurs (affected employees) must be trained to recognize when an energy-control procedure is being used. They should understand the purpose of the procedure and the importance of not tampering with lockout and tagout devices and not starting or using locked or tagged-out equipment.
Training for the control of hazardous energy is mandated by state and federal laws. Additional resources for the topic can be found on the Oregon OSHA website.
Why do we disable the equipment?
The goal of locking and tagging equipment during service and maintenance is to protect employees from exposure to serious physical harm or death from hazardous energies —electrical, mechanical, hydraulic, pneumatic, chemical, thermal, and other energy sources.
Service or maintenance includes erecting, installing, constructing, repairing, adjusting, inspecting, unjamming, setting up, trouble-shooting, testing, cleaning, and dismantling machines, equipment, or processes.
According to OSHA, compliance with lockout/tagout standards prevents an estimated 120 fatalities and 50,000 injuries each year in the United States.
How Energy Becomes Hazardous
Energy becomes hazardous when it builds to a dangerous level or is released in a quantity that could injure a worker. Hazardous energy is never far from those who need to service or maintain equipment. Simply turning the power off does not make the equipment safe! It is critical that those who service or repair equipment know how hazardous energy could harm them and how to control it.
To control hazardous energy, you must prevent it from being transmitted from its source to the equipment that it powers. You can accomplish that by doing the following:
- Identify energy sources and energy-isolating devices
- De-energize equipment
- Secure energy-isolating devices in a safe position
- Dissipate or restrain potential energy that can't be isolated
- Verify equipment isolation
1. Identifying energy sources and energy-isolating devices
Identify equipment in your workplace that needs service or maintenance. Determine the types of energy (there may be more than one) that powers the equipment, including potential energy that may remain when the energy sources are disconnected.
Types of Energies
|Chemical||Liquids, such as gasoline, diesel, benzene, acids, and caustics. Gases, such as propane, natural gas, and methane. Solids, such as fertilizer, wet and dry cell batteries, and combustible dust.|
|Electrical||Alternating (AC) and direct (DC) currents. Includes equipment and conductors at both household and industrial-voltages, photovoltaic systems, circuit breakers, transformers, capacitors, inverters, motors, and hybrid vehicles.|
|Gravitational||Objects such a hoisted vehicles, raised dumpster lids, objects supported by a crane, and elevated dump truck beds.|
|Hydraulic||Pressurized hydraulic systems, including hoses, pumps, valves, actuators, and reservoirs such as those on a forklift, in an automotive vehicle hoist, power press equipment, or an injection molding machine.|
|Mechanical||Sources such as a breeze rotating a wind turbine, water moving a paddle wheel, vehicle/mobile equipment movement, and a spring under compression. Extreme sound is also a hazardous mechanical energy.|
|Pneumatic||Pressurized air or gas systems, including pipes, pumps, valves, actuators, and pressure vessels such as those found in coating or pesticide sprayers, air compressors, and tank and pipe purging systems.|
|Radiation||Visible light, infrared, microwave, ultraviolet, and X-rays. Non-ionizing radiation includes lasers, radio frequency (RF), and microwave (MW). Ionizing radiation includes computed tomography (CT) and X-rays.|
|Thermal||Hot water, heated oil, steam, and equipment need time to cool, while liquefied gases, such as nitrogen, need time to warm to safe thermal levels.|
After identifying the energy sources, identify the devices that will effectively separate or block the energy from the equipment, preventing its activation or movement. Each energy source must be disconnected with an energy-isolating device (EID). Energy-isolating devices are mechanical devices that physically prevent the transmission or release of energy (i.e., switches and valves).
2. De-energizing equipment
Turn off or shut down equipment following established procedures. Stop buttons and on/off switches are used to shut down equipment, not to separate the equipment from its energy sources.
The method you use to de-energize equipment depends on the types of energy and the means to control it. After the equipment has been shut down, engage the equipment’s energy-isolating devices, physically separating the equipment from the energy. For compressed air, this could mean closing a specific manually operated valve. For an electric motor, this could mean opening a manually operated circuit breaker.
Energy-isolating devices can be:
- Disconnect switches (main)
- Line valves
- Manually operated electrical circuit breakers
- Bolted blank flanges
- Bolted slip blinds
- Safety blocks
- Any similar device used to block or isolate energy
Safe practices for de-energizing equipment:
- Disconnect equipment from energy sources.
- Disconnect motors from the equipment.
- Disconnect electrical circuits (including batteries).
- Block the fluid flow in hydraulic, pneumatic, or steam systems with control valve, blinds, or both.
- Block equipment parts or materials that could be moved by gravity.
3. Secure energy-isolating devices in a safe position
When equipment has been shut down, then de-energized using an energy-isolating device, nothing will prevent the energy-isolating device from accidentally (or intentionally) being turned on, reopened, or reactivated until it is secured.
Locking out, also known as lockout (LO), is a procedure for physically securing energy-isolating devices in an off, closed, or neutral position. Locking out is the preferred method of isolating machines or equipment from energy sources.
A lockout device – typically a lock with a unique key – secures the energy-isolating device in a safe position. When an energy-isolating device is secured by a lockout device, it physically prevents the energy-isolating device from being manipulated.
Each authorized employee must place their own personal lockout device on the energy-isolating devices; nobody can help an authorized person by fastening their lock to an energy-isolating device.
Tagging out, also known as tagout (TO), when performed correctly, is a procedure for securing a warning sign to an energy-isolating device when a lockout device cannot be used. A tag is used to inform other persons that each authorized employee is working on the equipment, and as long as the tag and lock remains attached, the authorized person in charge of the group lockout or tagout knows that the work has not been completed and that it is not safe to re-energize the equipment.
Tags are only warning devices and do not provide physical restraint. Tags may evoke a false sense of security and must be understood as part of an overall procedure. Only use a tagout system if an isolating device cannot be locked out, or there is demonstration that a tagout system provides full employee protection.
4. Dissipate or restrain potential energy that can’t be isolated
Stored energy must be released or restrained after equipment has been de-energized.
Capacitors; coiled springs; elevated machine parts; rotating flywheels; and air, gas, steam, chemical, and hydraulic systems are sources of stored energy. If the energy could return to a hazardous level, make sure that it remains isolated from the equipment until all service work is finished.
Safe practices for dissipating potential energy:
- Drain pressurized fluids or gases until internal pressure levels reach atmospheric levels.
- Discharge capacitors by grounding them.
- Double block and bleed process piping.
- Release or block tensioned springs.
- Ensure that all moving parts, such as flywheels and saw blades, have come to a complete stop.
- Allow equipment components to cool (or warm) to safe thermal levels.
Just shutting off the air supply to an automatically operated air valve or turning off a hydraulic power unit without bleeding off the pressure does not constitute energy isolation. Energy isolation is achieved when there is no energy left to be released.
5. Verify equipment isolation
It’s your last chance! Verification means purposely confirming that equipment is separated from its energy source; therefore it is "isolated." The authorized employee must verify that:
- Equipment has been properly turned off/shut down.
- Energy-isolating devices were identified and used to effectively isolate energy.
- Lockout or tagout devices have been attached to the energy-isolating devices.
- Stored energy has been removed or controlled.
Attempting to restart the equipment is one way to confirm isolation; however, testing equipment ensures that capacitors have been properly discharged, hazardous heat has dissipated, and excessive pressures have been relieved.
Temporary removal is allowed when re-energizing equipment is necessary, for example, when power is needed to test or position the equipment. This applies only for the limited time required to perform the task. Never temporarily remove any locking devices or tags without proper procedure documentation.
Returning Equipment to Service
To re-energize equipment after completing service and maintenance, employees must:
- Remove tools and replace equipment components, including guards
- Inform co-workers that lockout or tagout devices will soon be removed
- Ensure all workers are clear of the work area
- Verify power controls are off or in a neutral position
- Remove the lockout or tagout device
- Re-energize equipment
EVALUATION: Once you have completed the above training, complete the Lockout/Tagout Quiz. You must score at least an 80% to pass.