The Fundamentals of Lockout/Tagout

The Occupational Safety and Health Administration’s (OSHA) lockout/tagout standard (29 CFR 1910.147) is meant to protect the more than 3 million employees who service or maintain machinery from severe injury or death while conducting their work.

OSHA estimates that complying with the standard prevents about 120 fatalities and 50,000 employee injuries each year. That’s the good news. Unfortunately, many companies fall short in this area with disastrous results. In 2017 alone, the federal agency doled out 3,131 citations for violations of 1910.147.

Lockout/tagout refers to detailed procedures designed to control hazardous energy when employees perform service or maintenance activities, such as inspecting, installing, setting up, constructing or adjusting machinery or equipment. Specifically, this work might involve:

  • Lubricating 
  • Cleaning 
  • Removing jams
  • Making adjustments
  • Changing tools 

The unexpected release of hazardous energy can occur if:

  • Energy sources are not identified
  • Safe work practices are not established and communicated
  • Deactivated energy sources are reactivated without a worker’s knowledge

When one thinks of lockout/tagout, electricity often comes to mind. However, the standard pertains to all sources of energy, for example:

  • Mechanical (Kinetic) — Energy created by the moving parts of machinery
  • Electrical — Energy generated from electricity, static sources or electrical storage devices (such as batteries or capacitors)
  • Potential — Energy that is stored in pressure vessels, hydraulic or pneumatic systems, gas tanks and springs
  • Thermal — Energy that is formed as a result of mechanical work, radiation, a chemical reaction or electrical resistance

Definitions

Some key terms play an important role in lockout/tagout:

  • An energy-isolating device is a mechanical device that physically prevents the transmission or release of energy to machinery or equipment. Examples include: manually operated electrical circuit breakers, main disconnect switches, as well as line valves and blocks.
  • A lockout device is a lock, either key or combination type, that holds an energy-isolating device in a safe position, meaning machinery and equipment cannot be restarted.
  • A tagout device is a tag or sign (and its means of attachment), which is securely fastened to an energy-isolating device indicating that the equipment cannot be operated. Tagout devices do not provide the physical barrier to hazardous energy that lockout devices provide.

Your Energy Control Program

The lockout/tagout standard requires employers to establish an energy control program. Specifically, you must:

  • Document the procedures for removing the energy supply from machines and equipment, and for placing the appropriate lock or tag on the energy-isolating device to prevent unexpected energization.
  • Train employees on the program, including the safe application, use and removal of energy controls.
  • Inspect these procedures periodically to ensure their effectiveness.

With few exceptions, your actual written plan must include:

  • A statement on how and when to use energy control procedures
  • Steps to shut down, isolate, block and secure machines
  • How to safely place, remove and transfer lockout/tagout devices, and who has responsibility for the devices
  • Requirements for testing machines to verify the effectiveness of locks and tags, as well as other energy control measures

In addition, OSHA requires that:

  1. Each authorized employee (the person who actually performs the locking or tagging out of machinery) is trained to recognize: 1) Applicable hazardous energy sources, 2) the type and magnitude of the energy that exists in the workplace and 3) the methods and means necessary for energy isolation and control
  2. Each affected employee (usually a machine operator who works on the relevant machinery or works in the area) is instructed on the purpose and use of the energy control procedure.
  3. Other employees whose work operations are located where energy control procedures are implemented are instructed on lockout/tagout and the fact that any attempt to restart or reenergize machinery that is locked or tagged out is prohibited.
  4. When tagout systems are used, employees must also be trained on the limitations of tags.