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Lockout/Tagout

Many workplace injuries are caused by machinery that "accidentally" becomes activated while being serviced or maintained. This unintended activation is called an "uncontrolled release of hazardous energy." Many of these incidents can be prevented if the energy sources are isolated, and locked or tagged out. The Occupational Safety and Health Administration regulation on the Control of Hazardous Energy is 29 CFR 1910.147. This regulation helps safe guard workers from hazardous energy while they are performing service or maintenance on machines and equipment.

Identifying hazardous energy

Hazardous energy can be found in the workplace in different forms. The most common form of energy is electrical, but mechanical, hydraulic, pneumatic, chemical and thermal energy can also be dangerous. Energy can also mean movement or the possibility of movement. There are two types of energy.

• Kinetic energy is the force caused by the motion of an object. A spinning wheel is an example of kinetic energy. Bar screens or clarifiers can also hold kinetic energy.
  
  
• Potential energy is the force stored in an object that is not moving. A spring under tension is an example of potential energy. Garbage compactors and gravel crushers are also examples. Potential energy can also be the potential energy from suspended parts or springs.
  
  

Whenever any part of the body is exposed to these types of energy while servicing or maintaining equipment, lockout/tagout procedures must be followed.

Lockout/Tagout

To keep equipment from being energized during repairs or maintenance, it can usually be locked out. An energy isolating device (the disconnect switch or valve) is placed in the off position. A lock, either combination or key, is then placed over the energy-isolating device. This lock remains over the energy source until servicing or maintenance is completed.

A piece of machinery is tagged out when the machine is turned off and a tag with a written warning is attached to the disconnect switch, circuit breaker, valve or other energy-isolating device. The purpose of the tag is to assure that the equipment will not be operated until the tag has been removed. Tags used with the lock also identify the worker who is servicing the equipment.

Lockout/tagout is required in water and wastewater facilities where servicing and maintenance of machines and equipment could cause injury to workers due to unexpected startup or release of stored energy. Such situations could occur when repairing electrical circuits, cleaning or oiling machinery with moving parts, or clearing jammed mechanisms.

Some examples of machine maintenance requiring lockout/tagout are listed below:

• The worker must either remove or bypass machine guards or other safety devices, resulting in exposure to hazards at the “point of operation.” (The point of operation is an area on a machine or piece of equipment where work is actually done upon the material being processed);
  
  
• The worker is required to place any part of his or her body in contact with the point of operation of the operational machine or piece of equipment.
  
  
• The worker is required to place any part of his or her body into an area on the machine where it could be caught by moving parts.
  
  

Lockout is often bypassed because it is difficult and takes too much time when there may be pressure to get a piece of equipment back on line. To avoid the temptation to bypass lockout procedures, lockout should be as easy and as fast as possible.

Lockout vs. Tagout

Lockout is the most effective means of controlling hazardous energy because locks provide a physical restraint. They cannot be removed without a key. The key is in the possession of the employee working on the machine. Tags are not as effective because they can be removed or ignored by someone who is not aware that the machine is being repaired. According to OSHA, tags may only be used in two situations:

• When locks cannot be used.
  
  
• When the employer can demonstrate that a tagout system will provide full employee protection. Full employee protection is a strict set of procedures that the employer must follow to ensure that workers are provided with the same level of safety as using lockout procedures. These may include: removing a valve handle, blocking a controlling switch or other measures that will reduce the potential for any accidental energizing while tags are attached.
  
  

Tagout program

When the tagout program is used, it is essential that workers be trained in the limitations of the tags.

• Tags are only warning devices. They do not provide the physical restraints that the locks do.
  
  
• Tags can provide a false sense of security and their meaning may not be understood if all affected workers have not been properly trained.
  
  
• It is easier to bypass or ignore a tag or remove it without authorization.
  
  
• Tags may not be effective unless they can be read and understood by all authorized and affected workers, and all other workers who may work in the area.
  
  
• Tags can fall off or be knocked off unless they are securely attached.
  
  

Equipment

Lockout and tagout devices must be durable and substantial so they can withstand the environment. Wet conditions or chemicals (such as acids) used in the area must not destroy the tags or make them unable to be read. They must be attached so that they cannot accidentally fall off or be easily removed. Simple cardboard tags attached by string or wire are not permitted. Tags used outside should be in plastic covers.

Both lockout and tagout devices must be standardized according to their color, shape or size. Tagout devices must also be standardized according to print and format. This means that only the employer’s devices can be used for lockout/ tagout.

Locks and tags should be identifiable. They must show the identity of the employee who applied the device. Tags must also warn against hazardous conditions with messages that read “DO NOT START, DO NOT OPEN, DO NOT CLOSE, DO NOT ENERGIZE or DO NOT OPERATE.”

Applying lockout/tagout

In preparation for lockout/tagout, the worker and supervisor should agree on the equipment being taken out of operation and type and amount of the energy which needs to be controlled. All workers who will be affected by the lockout/ tagout should be notified and advised of the reason. The machine or equipment must be shut down in the normal fashion (pushing the “stop” button, closing a valve, throwing a switch, etc.) to avoid any additional hazards to workers.

The authorized employee(s) who will service the equipment should locate and identify all energy-isolating devices. Locking out one source of power to a piece of equipment may not be enough. Some machines use a combination of power supplies. If the main power source has been turned off, then so should the backup generator.

Locks should be attached to each energy-isolating device in a way that will hold the device in a “safe” or “off” position. Tags must be put in the same location a lock would be placed. Only the locks and tags supplied by the employer are to be used. Every worker in the crew must attach his or her personal lock. More than one worker can lock out a single energy isolating device by using a multiple lock hasp.

If tags are used instead of locks, they should be attached at the same point as a lock, or as close as possible where they will be immediately obvious to anyone attempting to operate the device. Remember, the tags must be filled out completely and correctly.

Steps must be taken to guard against energy left in the equipment after it has been isolated from its energy sources. The authorized employee(s) must make sure that all parts have stopped moving, tension in springs have been released, piping systems have been drained, valves have been closed and lines have been blocked.

Use a lockout device if your lock cannot be placed directly on the energy control. A lockout device is a device that physically keeps the machine from being turned on, operating or releasing energy. When this device is used, each worker in the work crew must attach his or her personal lock. Lockouts are designed to hold many padlocks. This provides additional protection for the entire service team since the controls cannot be operated until each member of the team has removed his/her lock. Keys for the locks should remain with and be used only by the those working on the job.

Before starting work on locked out equipment, authorized employees must know that the equipment has been de-energized by showing that the main disconnect switch or circuit breaker can’t be moved to the on position, by pushing buttons or other normal operating control(s) and/or by other tests to make sure that the equipment will not operate.

Release from lockout/tagout

Before the last lock or tag is removed, the worker should check to ensure that all tools have been removed from the work area and the system is completely re-assembled.

• As each worker completes his or her repairs, they should each remove their own lock or tag.
  
  
• All workers are clear of the hazard; all workers who work in the area are notified the lockout/tagout is being removed.
  
  

The supervisor should then be advised that the equipment is ready to be put back in service.

Inspections

Inspections of the energy control procedures must be performed annually by an authorized employee. The inspection process must consist of a review of the lockout/tagout procedures and correct any deficiencies found.

Training

As important as a lockout/tagout program is, it can only be effective if workers are aware of the program and trained properly. The amount and type of training that workers receive depends on their job in relation to the machine that is being locked out or tagged out.

Workers who are authorized to execute the lockout/tagout and perform the servicing or maintenance (“authorized employees”) should receive training in following:

• The recognition of all applicable hazardous energy sources (electrical, mechanical, hydraulic, pneumatic, chemical and thermal);
  
  
• Details about the type and size of the hazardous energy sources present in the workplace; and
  
  
• Methods necessary for controlling and isolating the energy source.
  
  

Authorized employees must possess the knowledge and skills necessary for the safe application, use and removal of energy controls.

“Affected/Other Employees” are usually the machine operators or users and all other workers whose work operations may be in the area of the energy controls. These workers need to recognize when the control procedure is being set in motion. They also need to understand the purpose of the procedure and the importance of not using or starting up any equipment or machines that are locked out or tagged out.

Lockout/tagout procedures do require additional time and effort, but can be well worth it. These workplace procedures give workers the tools needed to work safely around hazardous energy sources, prevent injuries and save lives.

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