Facility Safety Management

Our Mission Contact Us Subscribe Media Kit Previous Issues Web Links

NIOSH Guide For Controlling Hazardous Energy
BY LAQUITA OWENS

Workers who install or service equipment and systems may be injured or killed by the uncontrolled release of hazardous energy.

To prevent this, the National Institute for Occupational Safety and Health recommends taking the following steps to protect employees who install or service equipment and systems that can release electrical, mechanical or other types of hazardous energy:
• Follow OSHA regulations;
• Identify and label all sources of hazardous energy;
• De-energize all sources of hazardous energy;
• Disconnect or shut down engines or motors;
• De-energize electrical circuits;
• Block fluid (gas or liquid) flow in hydraulic or pneumatic systems;
• Block machine parts against motion;
• Block or dissipate stored energy;
• Discharge capacitors;
• Release or block springs that are under compression or tension; and
• Vent fluids from pressure vessels, tanks or accumulators—but never vent toxic flammable or explosive substances directly into the atmosphere.
Lockout and tagout all forms of hazardous energy including electrical breaker panels, control valves, etc. Make sure that only one key exists for each of the assigned locks and that only the person
locking out holds that key.

Verify by test and/or observation that allenergy sources are de-energized. Inspect repair work before removing locks and activating the equipment. Make sure that only person locking out removes the assigned lock.
Make sure that all workers a
re clear of danger points before re-energizing the system. Only the worker who installs a lock and tag should remove them after work is complete and inspected.
These recommendations are described in more detail in the following sections.

1. Comply with OSHA regulations.
Employers and workers must comply with OSHA regulations for controlling hazardous energy during maintenance and installation work (see 29 CFR 1910.146,
1910.147, 1910.177, 1910.178, 1910.179,
1910.181, 1910.213, 1910.217, 1910.218,
1910.261, 1910.262, 1910.263, 1910.265,
1910.269, 1910.272, 1910.305, 1910.306,
1910.333, 1926.416, and 1926.417).
OSHA standards and accepted safe work practices require employers to ensure that all hazardous energy sources are de-energized before work begins. If these sources cannot be de-energized, OSHA requires employers to protect workers with insulation, guarding, and appropriate personal protective equipment.

2. Implement a hazardous energy control program.
Employers should develop and implement a written hazardous energy control program that, at a minimum does the following:
• Describes safe work procedures;
• Establishes formal lockout/tagout procedures;
• Trains all employees in the program; and
• Enforces the use of the procedures (including disciplinary action for failure to follow them). Hazardous energy control programs should outline the following safe work practices:
• Identify tasks that may expose workers to hazardous energy.
• Identify and de-energize all hazardous energy sources, including those in adjacent equipment.
• Lockout and tagout all energy-isolating devices to prevent inadvertent or unauthorized reactivation or startup.
• Isolate, block, and/or dissipate all hazardous sources of stored or residual energy, including those in adjacent equipment.
• Before beginning work, verify energy isolation and de-energization, including that in adjacent equipment or energy sources.
• After work is complete, verify that all personnel are clear of danger points before re-energizing the system.

Hazardous energy control among work groups must be coordinated when multiple employers are involved in large projects and when shift changes occur during such activities. Outside contractors
should work with the facility owner to make sure that an adequate hazardous energy control program is implemented specifically for contract workers.

3. Identify and label all hazardous energy sources. Employers should use jobsite surveys to ensure that all hazardous energy sources (including those in adjacent equipment) are identified before beginning any installation, maintenance, service, or repair tasks. Hazardous energy includes mechanical motion, potential or stored energy, electrical energy, thermal energy and chemical reactions.Energy-isolating devices such as breaker panels and control valves should be clearly labeled.

4. De-energize, isolate, block, and/or dissipate all forms of hazardous energy.
All forms of hazardous energy should be de-energized, isolated, blocked, and/or dissipated before workers begin any installation, maintenance, service, or repair work. The method of energy control
depends on the form of energy involved and the available means to control it. Energy is considered to be isolated or blocked when its flow or use cannot occur [NIOSH 1983].

To isolate or block energy, take the following steps:
• Disconnect or shut down engines or motors that power mechanical systems;
• De-energize electrical circuits by disconnecting the power source from the circuit;
• Block fluid (gas, liquid, or vapor) flow in hydraulic, pneumatic, or steam systems by using control valves or by capping or blanking the lines; Lines can be blanked by inserting a solid plate between
the flanges of a joint; and
• Block machine parts against motion that might result from gravity (falling).
Some forms of energy must also be dissipated after a system has been de-energized. System components such as electrical capacitors, hydraulic accumulators, or air reservoirs may retain sufficient energy to cause serious injury or death even though the component has been de-energized, isolated or blocked from the system and locked out.
Energy can be dissipated by taking the following steps:
• Vent fluids from pressure vessels, tanks, or accumulators until internal pressure is at atmospheric levels. However, do not vent vessels or tanks containing toxic, flammable, or explosive substances
directly to the atmosphere.
• Discharge capacitors by grounding.
• Release or block springs that are under tension or compression.
• Dissipate inertial forces by allowing the system to come to a complete stop after the machine or equipment has been shut down and isolated from its energy sources.

5. Establish lockout/tagout programs requiring individually assigned locks and keys to secure energy control devices. Lockout/tagout programs should be based on the principle of only one key for each lock the worker controls. This means the following:
Workers are assigned individual locks operable by only one key for use in securing energy control devices (breaker panels, control valves, manual override switches, etc.).
Each worker maintains custody of the key for each of his or her assigned locks. Use of master keys should be reserved for unusual circumstances when the worker is absent from the workplace.
However, if master keys are necessary, keep them under supervisory control. List the proper procedures for using them in the written program for controlling hazardous energy.
Each lock is labeled with a durable tag or other means that identifies its owner.
When work is performed by more than one worker, each worker applies his or her own lock to the energy-securing device. Scissors-type hasps made of hardened steel are available to facilitate
the use of more than one lock to secure an energy control device. All de-energized circuits and systems are clearly labeled with durable tags.
The worker who installs a lock is the one who removes it after all work has been completed.
If work is not complete when the shift changes, workers arriving on shift apply their locks before departing workers remove their locks.
Because tags can be easily removed, they are not a substitute for locks. Workers are safest with a program that uses both locks and warning tags to prevent systems from being inadvertently re-energized.

6. Verify that all energy sources are de-energized before work begins. Employers should establish and enforce company policies requiring workers to verify that all energy sources are de-energized
before work begins. This verification should ensure that all energy sources (including stored energy) are controlled (that is, de-energized, isolated, blocked, and/or dissipated) before work begins.
Appropriate testing equipment should be required as needed.

7. Inspect repair work before reenergizing the equipment. To ensure that equipment will operate as expected when it is re-energized, employers should require qualified persons to inspect completed installation, maintenance, service or repair work.
The inspection should verify that installation, repairs, and modifications were performed correctly and that the correct replacement parts were used. When equivalent or updated parts must be substituted
for original parts, the system may need to be modified.
Re-energized equipment should be closely monitored for several operating cycles to ensure that it is functioning correctly and safely.

8. Make sure that all persons are clear of danger points before re-energizing the system.
Employers should develop procedures to verify that all persons are clear of danger points before re-energizing the system. Locks and tags should be removed only by the workers who installed
them—and only after workers have been cleared from the danger points. This may require visual inspections and searches of areas around machinery or electrical circuits to assure that workers will
not be exposed to the release of hazardous energy when equipment is re-energized. Workers should be informed about impending equipment start-up with warning devices they can see and hear.
Such devices will help assure that workers are clear before equipment is re-energized.

9. Train workers in the basic concepts of hazardous energy control.
Employers should train ALL workers in the basic concepts of hazardous energy control, including energy isolation, locking and tagging of control devices, verifying de-energization, and clearing danger points before re-energizing equipment.
Workers whose duties involve installation, maintenance, service or repair work should be trained in the detailed control procedures required for their particular equipment. This training should enable workers to identify tasks that might expose them to hazardous energy and the effective methods for its
control.

10. Include a hazardous energy control program with any confined-space entry program.
When work requires entry into confined spaces such as utility vaults or tanks, employers should incorporate a hazardous energy control program as part of their confined-space entry program—according to OSHA standards [29 CFR 1910.146 and 1910.147] and published NIOSH guidelines [NIOSH 1979, 1987].

11. Design machines and systems that make it easy to control hazardous energy.
Employers should encourage manufacturers to design control valves, switches, and equipment that are easy to access and lockout. FSM