29 CFR 1910.147, the Control
of Hazardous Energy (Lockout/Tagout)--Inspection Procedures and Interpretive
Purpose. This instruction establishes
policies and provides clarification to ensure uniform enforcement
of the Lockout/Tagout Standards.
Scope. This instruction applies OSHA-wide.
General Industry Standards, 29 CFR
1910, Subpart O, Subpart S, and other specific subparts.
OSHA Instruction CPL 2.45B, June
15, 1989, the Revised Field Operations Manual (FOM).
Effective Date of Requirements. All requirements
of 29 CFR 1910.147 have an effective date of January 2, 1990.
The information collection requirements contained in this section
have been approved by the Office of Management and Budget (OMB)
and listed under OMB control number 1218-0150, as announced at
Federal Register, Volume 54, No. 199, October 17, 1989.
Action. Regional Administrators and Area
Directors shall ensure that the guidelines and interpretive guidance
in this instruction are followed and that compliance officers
are familiar with the contents of the standard.
Federal Program Change. This instruction
describes a Federal program change which affects State programs.
Each Regional Administrator shall:
Ensure that this change is forwarded
to each State designee.
Explain the technical content of
this change to the State designee as requested.
Ensure that State designees acknowledge
receipt of this Federal program change in writing, within
30 days of notification, to the Regional Administrator. This
acknowledgment should include the State's intention to follow
the inspection guidelines described in this instruction, or
a description of the Stat's alternative guidelines which are
"at least as effective" as the Federal guidelines.
If a State intends to follow
the revised inspection guidelines described in this instruction,
the State must submit either a revised version of this
instruction, adapted as appropriate to reference State
law, regulations and administrative structure, or a cover
sheet describing how references in this instruction correspond
to the State's structure. The State's acknowledgment letter
may fulfill the plan supplement requirement if the appropriate
documentation is provided.
Any alternative State inspection
guidelines must be submitted as a State plan supplement
within 6 months. If the State adopts an alternative to
Federal guidelines, the State's submission must identify
and provide a rationale for all substantial differences
from Federal guidelines in order for OSHA to judge whether
a different State guideline is as effective as a comparable
After Regional review of the State
plan supplement and resolution of any comments thereon, forward
the State submission to the National Office in accordance
with established procedures. The Regional Administrator shall
provide a judgment on the relative effectiveness of each substantial
difference in the State plan change and an overall assessment
thereof with a recommendation for approval or disapproval
by the Assistant Secretary.
Review policies, instructions and
guidelines issued by the State to determine that this change
has been communicated to State personnel.
Background. The Standard for Control
of Hazardous Energy (Lockout/Tagout), 29 CFR 1910.147, was promulgated
on September 1, 1989, at Federal Register, Volume 54, No. 169
(pages 36644-36696), and was effective on January 2, 1990, as
announced at Federal Register, Volume 54, No. 213, November 6,
1989 (page 46610). Previously existing section 29 CFR 1910.147
was redesignated as 29 CFR 1910.150, Sources of Standards.
Since the inception of its enforcement
program, OSHA has relied on the "General Duty Clause" (Section
5(a)(1) of the OSH Act) to ensure that employers safeguarded
their maintenance and service employees through the use of
lockout/tagout from the hazards involving the unintentional
release of hazardous energy. Such violations reached a level
so significant that the development and promulgation of a
lockout/tagout standard was required.
The new rule addresses practices
and procedures that are necessary to disable machinery or
equipment and to prevent the release of potentially hazardous
energy while maintenance and servicing activities are being
The lockout/tagout provisions of
this standard are for the protection of general industry workers
while performing servicing and maintenance functions and augment
the safeguards specified at Subparts O, S, and other applicable
portions of 29 CFR 1910.
Inspection Guidelines. The standard
incorporates performance requirements which allow employers flexibility
in developing lockout/tagout programs suitable for their particular
The compliance officer shall determine
whether servicing and maintenance operations are performed
by the employees. If so, the compliance officer shall further
determine whether the servicing and maintenance operations
are covered by 29 CFR 1910.147 or by the requirements or employee
safeguarding specified by other standards as discussed in
Evaluations of compliance with 29
CFR 1910.147 shall be conducted during all general industry
inspection within the scope of the standard in accordance
with the FOM, Chapter III, D.7. and 8., Additional Information
to Supplement Records Review. The review of records shall
include special attention to injuries related to maintenance
and servicing operations.
The compliance officer shall evaluate
the employer's compliance with the specific requirements of
the standard. The following guidance provides a general framework
to assist the compliance officer during inspections:
Ask the employer for any hazard
analysis or other basis on which the program related to
the standard was developed. Although this is not a specific
requirement of the standard, such information, when provided,
will aid in determining the adequacy of the program. It
should be noted that the absence of a hazard analysis
does not indicate non-compliance with the standard.
Ask the employer for the documentation
including: procedures for the control of hazardous energy
including shutdown, equipment isolation, lockout/tagout
application, release of stored energy, verification of
isolation; certification of periodic inspections; and
certification of training. The documented procedure must
identify the specific types of energy to be controlled
and, in instances where a common procedure is to be used,
the specific equipment covered by the common procedure
must be identified at least by type and location. The
identification of the energy to be controlled may be by
magnitude and type of energy. Note the exception to documentation
requirements at paragraph 1910.147(c)(4)(i), "Note". The
employer need not document the required procedure for
a particular machine or equipment when all eight(8) elements
listed in the "Note" exist.
Evaluate the employer's training
programs for "authorized", "affected", and "other" employees.
Interview a representative sampling of selected employees
as a part of this evaluation (29 CFR 1910.147 (c)(7)(i)).
Verify that the training
of authorized employees includes:
Recognition of hazardous
Type and magnitude
of energy found in the workplace;
The means and methods
of isolating and/or controlling energy; and
The means of verification
of effective energy control, and the purpose
of the procedures to be used.
Verify that affected employees
have been instructed in the purpose and use of the
energy control procedures.
Verify that all other
employees who may be affected by the energy control
procedures are instructed about the procedure and
the prohibition relating to attempts to restart
or reenergize such machines or equipment.
When the employer's procedures
permit the use of tagout, the training of authorized,
affected, and other employees shall include the
provisions of 29 CFR 1910.147(c)(7)(ii) and (d)(4)(iii).
Evaluate the employer's manner
of enforcing the program (29 CFR 1910.147 (c)(4)(ii)).
In the event that deficiencies are
identified by following the guidelines in H.3. of this instruction,
the compliance officer shall evaluate the employer's compliance
with specific requirements of the standard, with particular
attention to the interpretive guidance provided in section
I. and to the following:
Evaluate compliance with the
requirements for periodic inspection of procedures.
Ensure that the person performing
the periodic inspection is an authorized employee other
than the one(s) utilizing the procedure being inspected.
Evaluate compliance with retraining
requirements which result from the periodic inspection
of procedures and practices, or from changes in equipment/processes.
Evaluate the employer's procedures
for assessment, and correction of deviations of inadequacies
identified during periodic inspections of the energy control
Identify the procedures for
release from lockout/tagout, including:
Replacement of safeguards, machine
or equipment inspection, and removal of non-essential
tools and equipment;
Safe positioning of employees;
Removal of lockout/tagout device(s);
Notification of affected employees
that servicing and maintenance is completed.
Ensure that when group lockout
or tagout is used, it affords a level of protection equivalent
to individual lockout or tagout as amplified in I.7. through
I.9. of this instruction.
The lockout/tagout standard is a
performance standard; therefore, additional guidance is provided
in Appendix C of this instruction to assist in effective implementation
by employers and for uniform enforcement by OSHA field staff.
Interpretive Guidance. The following
guidance relative to specific provisions of 29 CFR 1910.147 is
provided to assist compliance officers in conducting inspections
where the standard may be applicable:
Scope of the Standard.
The standard as specified in
29 CFR 1910.147(b), applies to any source of mechanical,
hydraulic, pneumatic, chemical, thermal, or other energy.
The standard applies to piping
systems, and requires, at 29 CFR 1910.147(d)(5),
that all potentially hazardous stored or residual
energy be relieved, disconnected, restrained, and
otherwise rendered safe. If there is a possibility
of reaccumulation of stored energy to a hazardous
level, continued monitoring shall be performed while
a potential hazard exists.
The standard also applies to
high intensity electromagnetic fields regulated
at 29 CFR 1910.97, nonionizing radiation. Such electromagnetic
devices shall be deenergized and held off whenever
workers are present within a high intensity ambient
Servicing/maintenance of fire
alarm and extinguishing systems and their components,
upon which other employees are dependent for fire
safety, are not required to meet the requirements
of this standard if the workers performing servicing/maintenance
upon fire extinguishing systems are protected from
hazards related to the unexpected release of hazardous
energy by appropriate alternative measures. (See
29 CFR 1910, Subpart L.)
The standard does not apply to
servicing and maintenance when employees are not exposed
to the unexpected released of hazardous energy.
Safeguarding workers from the
hazards of contacting electrically live parts (exposure
to electric current) continues to be regulated at Subpart
Servicing and maintenance functions
conducted during normal production operations are not
regulated at 29 CFR 1910.147 if the safeguarding provisions
of Subpart O or other applicable portions of 29 CFR 1910
prevent worker exposure to hazards created by the unexpected
energization or start-up of the machine or equipment.
However, lockout/tagout procedures are required if the
production safeguards are rendered ineffective while an
employee is exposed to hazardous portions of the machines
Generally, activities such as
lubrication, cleaning or unjamming, servicing of machines
or equipment, and making adjustments or tool changes,
where the employee may be exposed to the UNEXPECTED energization
or start-up of the equipment or release of hazardous energy,
are covered by this standard. However, minor tool changes
and adjustments, and other minor servicing activities,
which take place during normal production operations,
are not covered by this standard if they are routine,
repetitive, and integral to the use of equipment for production,
and if work is performed using alternative protective
measures which provide effective employee protection.
Thus, lockout or tagout is not required by this standard
if the alternative protective measures enable the servicing
employee to clean or unjam, or otherwise service the machine
without being exposed to unexpected energization or activation
of the equipment, or the release of stored energy.
NOTE: Appendix C, section A,
provides further guidance in this area.
The exclusion of plug and cord
connected electric equipment, at 29 CFR 1910.147(a)(2)(iii)(A),
applies only when the equipment is unplugged and the plug
is under the exclusive control of the employee performing
the servicing and/or maintenance.
The plug is under the exclusive
control of the employee if it is physically in the
possession of the employee, or in arm's reach and
in line of sight of the employee, or if the employee
has affixed a lockout/tagout device on the plug.
The company lockout/tagout procedures
required by the standard at 29 CFR 1910.147(c)(4)
shall specify the acceptable procedure for handling
cord and plug connected equipment.
The employer must develop and
document procedures and techniques to be used for the
control of hazardous energy. The standard, at 29 CFR 1910.147(c)(4)(i)
"Note," identifies eight (8) conditions that must exist
in order to excuse the employer's obligation to maintain
a written procedure for a specific machine or piece of
29 CFR 1910.147(d)(3) and (d)(5)
provide that energy isolation be a mandatory part of employer's
control procedure where either a lockout system or a tagout
system is used.
Similar machines and/or equipment
(such as those using the same type and magnitude of energy
and the same or similar types of controls) can be covered
with a single written procedure.
Lockout vs. Tagout.
OSHA has determined that lockout
is a surer means of ensuring deenergization of equipment
than tagout, and that it is the preferred method.
29 CFR 1910.147(c)(3)(ii) provides
that: When using a tagout program in those instances where
the equipment is capable of being locked out, the employer
shall demonstrate that the tagout program will provide
a level of safety equivalent to the obtained when using
a lockout program. Additional means beyond those necessary
for lockout are required. (Additional means include: additional
safety measures such as the removal of an isolating circuit
element, blocking of a controlling switch, opening of
an extra disconnecting device, or the removal of a valve
handle to reduce the likelihood of inadvertent energization.)
29 CFR 1910.147(c)(4)(ii) provides
that: Where lockout/tagout programs are used, the employer
is required to implement an effective means of enforcing
29 CFR 1910.147(c)(7)(ii)(A-F)
provide that: Additional training of authorized, affected
and other employees is required when tagout programs are
29 CFR 1910.147(c)(5)(ii)(A)
requires that lockout and tagout devices be capable of
withstanding the environment to which they are exposed.
Devices which are not exposed to harsh environments need
not be capable of withstanding such exposure.
29 CFR 1910.147(c)(5)(ii)(C)(2)
requires that tagout devices having reusable, non-locking,
easily detachable means of attachment (such as string,
cord, or adhesive) are not permitted.
Employees and Training.
The standard recognized three
types of employees: (1)"authorized" and (2)"affected",
defined in 1910.147 (b), and (3)"other", defined in 1910.147(c)(7)(ii)(C).
Different levels of training are required based upon the
respective roles of employees in the control of energy
and the knowledge which they must possess to accomplish
their tasks safely and to ensure the safety of fellow
workers as related to the lockout/tagout procedures (1910.147(c)(7)(i)).
Employees who exclusively perform
functions related to normal production operations, and
who perform servicing and/or maintenance under the protection
of normal machine safeguarding, need only be trained as
"affected" (rather than "authorized") employees even if
tagout procedures are used. (See, I.1.d. and I.1.e. of
The employer's training program
must cover, at a minimum, the following three areas: energy
control program, elements of energy control procedures
relevant to employee duties, and the pertinent requirements
of the standard (1910.147(c)(7) and (d) through (f)).
The employer must provide:
Effective initial training;
Effective retraining as needed;
Certification of training. The
certification shall contain each employee's name
and dates of training (1910.147(c)(7)iv)).
Retraining of authorized and affected employees is
Whenever there is a change in
employee job assignments;
Whenever a new hazard is introduced
due to a change in machines, equipment or process;
Whenever there is a change in
the energy control procedures; or
Whenever a periodic inspection
by the employer reveals inadequacies in the company
procedures or in the knowledge of the employees.
Periodic Inspection by the Employer
At least annually, the employer
shall ensure that an authorized employee other than the
one(s) utilizing the energy control procedure being inspected,
is required to inspect and verify the effectiveness of
the company energy control procedures. These inspections
shall at least provide for a demonstration of the procedures
and may be implemented through random audits and planned
visual observations. These inspections are intended to
ensure that the energy control procedures are being properly
implemented and to provide an essential check on the continued
utilization of the procedures (29 CFR 1910.147(c)(6)(i)).
When lockout is used, the employer's
inspection shall include a review of the responsibilities
of each authorized employee implementing the procedure
with that employee. Group meetings between the authorized
employee who is performing the inspection and all
authorized employees who implement the procedure
would constitute compliance with this requirement.
When tagout is used, the employer
shall conduct this review with each affected and
Energy control procedures used
less frequently than once a year need be inspected
only when used.
The periodic inspection must
provide for and ensure effective correction of identified
deficiencies (29 CFR 1910.147(c)(6)(i)(B)).
The employer is required to
certify that the prescribed periodic inspections have
been performed (29 CFR 1910.147(c)(6)(ii)).
Equipment Testing or Positioning.
Under 29 CFR 1910.147(f)(1), OSHA allows the temporary removal
of lockout or tagout devices and the reenergization of the
machine or equipment ONLY during the limited time necessary
for the testing or positioning of machines, equipment or components.
After the completion of the temporary reenergization, the
authorized employees shall again deenergize the equipment
and resume lockout/tagout procedures.
Group Lockout/Tagout. Group lockout/tagout
procedures shall be tailored to the specific industrial operation
and may be unique in the manner that employee protection from
the release of hazardous energy is achieved. Irrespective
of the situation, the requirements of this generic standard
specify that each employee performing maintenance or servicing
activities shall be in control of hazardous energy during
his/her period of exposure.
Group operations normally require
that a lockout/tagout program be implemented which ensures
that each authorized employee is protected from the unexpected
release of hazardous energy by his/her personal lockout/tagout
device(s). No employee may affix the personal lockout/tagout
device of another employee. Various group lockout/tagout
procedures discussed in Appendix C provide for each authorized
employee's use of his/her personal lockout/tagout device(s).
One of the most difficult problems
addressed by the standard involves the servicing and maintenance
of complex equipment. Such equipment is frequently used
in the petrochemical and chemical industries. Acceptable
group lockout/tagout procedures for complex equipment
are discussed further at Appendix C.
Compliance with Group Lockout/Tagout.
These operations shall, at a minimum, provide for the following:
Before the machine or equipment
is shut down, each authorized employee who is to be involved
during the servicing/maintenance operation shall be made
aware by the employer of the type, magnitude, and hazards
related to the energy to be controlled and of the method
or means to control the energy. In the event that the
machine or equipment is already shut down, the authorized
employee shall be made aware of these elements before
beginning his/her work (29 CFR 1910.147(d)(1)). Verification
shall be performed as noted at I.8.f. of this instruction.
An orderly shutdown of the machine
or equipment shall be conducted which conforms to the
documented company procedure and which will not create
hazards (29 CFR 1910.147(d)(2)).
All energy isolating devices
needed to isolate the machine or equipment shall be effectively
positioned and/or installed (29 CFR 1910.147 (d)(3)).
The authorized employee(s) performing
the servicing or maintenance (following the company procedure)
shall personally affix a lock or tag upon each energy
isolating device (29 CFR 1910.147(d)(4)(i). The company
procedure must ensure that no employee affixes a personal
lockout/tagout device for another employee.
A single lock upon each energy
isolating device, together with the use of a lockbox
for retention of the keys and to which each authorized
employee affixes his/her personal lock or tag, also
satisfies the requirement (29 CFR 1910.147(f)(3)(i)).
Locks shall be affixed in a manner
that will hold the energy isolating device in a
safe (off) position (29 CFR 1910.147(d)(4)(ii)).
Tagout devices, where used, shall
be affixed at the same location as would a lock
if such fittings are provided, or shall be affixed
in a manner that will clearly indicate that movement
of the isolating device is prohibited (29 CFR 1910.147(d)(4)(iii)).
Following the application of
locks or tags, all potentially hazardous stored energy
or residual energy shall be relieved, disconnected, restrained,
and otherwise rendered safe (29 CFR 1910.147(d)(5)(i)).
Verification of energy isolation
shall be monitored as frequently as necessary if
there is a possibility of reaccumulation of stored
energy (29 CFR 1910.147(d)(5)(ii)).
Monitoring may be accomplished,
for example, by observation or with the aid of a
monitoring device which will sound an alarm if a
hazardous energy level is being approached.
Authorized employees shall verify
that isolation and deenergization have been effectively
accomplished before starting servicing/maintenance work.
Verification is also necessary by each group of workers
before starting work at shift changes.
Release from lockout/tagout
shall be accomplished in compliance with the requirements
at 29 CFR 1910.147(e).
The machine or equipment area
shall be cleared of nonessential items to prevent
malfunctions which could result in employee injuries
29 CFR 1910.147(e)(1)).
The authorized employees shall
remove their respective locks or tags from the energy
isolating devices or from the group lock-box(s)
following the procedure established by the company
(29 CFR 1910.147(e)(3)).
In all instances, the company
procedure must provide a system which identifies
each authorized employee involved in the servicing/maintenance
Before reenergization, all employees
in the machine or equipment area shall be safely
positioned or moved from the area, and the affected
employees shall be notified that the lockout/tagout
devices have been removed (29 CFR 1910.147(e)(2)).
During all group lockout/tagout
operations where the release of hazardous energy is possible,
each authorized employee performing servicing or maintenance
shall be protected by his/her personal lockout or tagout
device and by the company procedure. As described at Appendix
C, B.1.g., a master tag is a personal tagout device if
each employee personally signs on and signs off on it
and if the tag clearly identifies each authorized employee
who is being protected by it.
Compliance of Outside Personnel.
Outside servicing and maintenance personnel (contractors,
etc.) engaged in activities regulated under 29 CFR 1910.147
are subject to the requirements of that standard.
The CSHO shall verify that the
outside employer and the on-site employer have exchanged
information regarding the lockout/tagout energy control
procedures used by each employer's workers (29 CFR 1910.147(f)(2)(i)).
The CSHO shall verify that the
on-site employer has effectively informed his/her personnel
of the restrictions and prohibitions associated with the
outside employer's energy control procedures (29 CFR 1910.147(f)(2)(ii)).
When an outside employer is
engaged in servicing and maintenance activities within
an on-site employer's facility and if that contractor's
activities are subject to the requirements of 29 CFR 1910.147,
the CSHO shall coordinate with the Area Director to obtain
permission to initiate an independent inspection of the
outside contractor's activities.
Appendix B contains an example of
a functional flow diagram to implement safe lockout/tagout
procedures. This flow diagram is presented solely as an aid
and does not constitute the exclusive or definitive means
of complying with the standard in any particular situation.
Classification of Violations.
A deficiency in the employer's
energy control program and/or procedure that could contribute
to a potential exposure capable of producing serious physical
harm or death shall be cited as a serious violation.
The failure to train "authorized",
"affected", and "other" employees as required for their respective
classifications should normally be cited as a serious violation.
Paperwork deficiencies in lockout/tagout
programs where effective lockout/tagout work procedures are
in place shall be cited as other-than-serious.
Evaluation. In keeping with agency policy, each Region shall
evaluate the effectiveness of the guidance in this instruction
annually. Each Regional Administrator shall submit a written evaluation
report to the Directorate of Compliance Programs within 30 days
of the close of the fiscal year.
Gerard F. Scannell
National, Regional, and Area Offices
All Compliance Officers
NIOSH Regional Program Directors
7(c)(1) Consultation Project Managers
OSHA Training Institute
The following listing indicates a number of OSHA
standards which currently impose lockout/tagout related requirements.
The list does not necessarily include all lockout/tagout related OSHA
29 CFR 1910 standards.
CONDUCT MACHINE/PROCESS DEVELOP DOCUMENTED
HAZARD ANALYSIS _________
____________________| DEVELOP TRAINING PROGRAM
| __________________________ |_________________________
| V V V
|PROVIDE TRAINING TO PROVIDE DETAILED TRAINING PROVIDE TRAINING TO
| AFFECTED EMPLOYEES TO AUTHORIZED EMPLOYEES ALL OTHER EMPLOYEES
| ASSIGN MAINT./SERVICE
| TASK TO
| AUTHORIZED EMPLOYEES
| ___________________________ AND
| | |
| V V
| CONSULT COMPANY NOTIFY AFFECTED
| PROCEDURES DOCUMENT EMPLOYEE(S) OF
| | MAINT./SERVICE OPS
| | IDENTIFY
| | ENERGY ISOLATING DEVICES
| | IDENTIFY & OBTAIN
| V __________________________
| ___________AND/OR__________ |
| | | |
| V V |
| DEACTIVATE & DEACTIVATE & |
| TAGOUT LOCKOUT |
| |_________________________| |
| | |
| V |
| VERIFY HAZARDOUS |
| ENERGY CONTROLLED |
| | |
HAZARDOUS ENERGY __________ OR |
NOT CONTROLLED | |
PERFORM TASK |
RETRIEVE TOOLS & EQUIPMENT |
VERIFY PERSONNEL |
CLEAR AND ACCOUNTED FOR |
REMOVE LOCKOUT/TAGOUT |
NOTIFY AFFECTED |
RETURN CUSTODY OF RESTORE POWER & PROBLEM
EQUIPMENT __________ VERIFY OPS ___________ IDENTIFIED
TO AFFECTED EMPLOYEE(S)
This appendix provides guidelines to assist
the compliance officer during evaluations of employer operations.
Normal Production Operations. The lockout/tagout
standard, 29 CFR 1910.147, addresses the safety of employees engaged
in servicing and maintenance activities in general industry workplaces.
The standard complements the requirements for machine and process
operator safety prescribed by the various general industry standards
in 29 CFR Part 1910. Subpart O of 29 CFR 1910 provides the principal,
though not exclusive, machine guarding requirements.
Safeguarding of servicing and maintenance
workers can be ensured either by:
Effective machine safeguarding
in compliance with Subpart O, or
Compliance with 29 CFR 1910.147 in situations where
the normal production operations safeguards are rendered
ineffective or do not protect the servicing/maintenance
Activities which are routine, repetitive,
and integral to the use of equipment for production are not
covered by this standard if alternative measures provide effective
worker protection from hazards associated with unexpected
energization. Compliance with the machine guarding requirements
of Subpart O is an example of such alternative measures. In
addition, supplemental personal protective equipment may be
necessary during a servicing or maintenance operation when
a toxic substance is to be isolated. Under such circumstances,
the requirements of applicable standards, such as 29 CFR 1910.134
and Subpart Z, also must be met.
An employer who requires employees
to perform routine maintenance and/or servicing while a machine
or process is operating in the production mode, must provide
employee safeguarding under the applicable requirements of
Subpart O. (Ref. 29 CFR 1910.212(a)(1)). Operations such as
lubricating, draining sumps, servicing of filters, and inspection
for leaks and/or mechanical malfunction are examples of routine
operations which can be accomplished with effective production-mode
safeguards. However, the replacement of machine or process
equipment components such as valves, gauges, linkages, support
structure, etc., is not considered to be normal routine maintenance
function which can safely be accomplished during machine or
process equipment operation. Such maintenance requires energy
isolation and should be evaluated by OSHA field staff. They
also may be an appropriate subject of a variance request.
Several alternative means of safeguarding the hazardous
portions of machines and equipment are presented by the national
consensus standard, ANSI B11.19-1990. Although that standard
is not all inclusive, it describes effective safeguarding
alternatives for the protection of employees. The safeguards
describe include: interlocked barrier guards, presence sensing
devices and various devices under the exclusive control of
the employee. Such devices or guards, properly applied, may
be used in clearing minor jams and performing other minor
servicing functions which occur during normal production operations
and which meet the criteria described in paragraph A.2. of
Group Lockout/Tagout. The group lockout/tagout
procedures described in this instruction at paragraph I.8. require
each authorized employee to be in control of potentially hazardous
energy release during their servicing/maintenance work assignments.
Under most circumstances, where servicing/maintenance is to be
conducted during only one shift by an individual or a small number
of persons working together, the installation of each individual's
lockout/tagout device upon each energy isolating device would
not be a burdensome procedure. However, when many energy sources
or many persons are involved, and/or the procedure is to extend
over more than one shift, (possibly several days, or weeks) consideration
must be given to the implementation of a lockout/tagout procedure
that will ensure the safety of the employees involved and will
provide for each individual's control of the energy hazards. The
following procedures are presented as examples to illustrate the
implementation of a group lockout/tagout procedure involving many
energy isolating devices and/or many servicing/maintenance personnel.
They illustrate several alternatives for having authorized employees
affix personal lockout/tagout devices in a group lockout/tagout
setting. These examples are not intended to represent the only
acceptable procedures for conducting group operations.
Definitions. Various terms used in
the examples are defined below.
PRIMARY AUTHORIZED EMPLOYEE is
the authorized employee who exercises overall responsibility
for adherence to the company lockout/tagout procedure.
(See 29 CFR 1910.147(f)(3)(ii)(A).)
PRINCIPAL AUTHORIZED EMPLOYEE
is an authorized employee who oversees or leads a group
of servicing/maintenance workers (e.g., plumbers, carpenters,
electricians, metal workers, mechanics).
JOB-LOCK is a device used to
ensure the continuity of energy isolation during a multi-shift
operation. It is placed upon a lock-box. A key to the
job-lock is controlled by each assigned primary authorized
employee from each shift.
JOB-TAG with TAB is a special
tag for tagout of energy isolating devices during group
lockout/tagout procedures. The tab of the tag is removed
for insertion into the lock-box. The company procedure
would require that the tagout job-tag cannot be removed
until the tab is rejoined to it.
MASTER LOCKBOX is the lockbox
into which all keys and tabs from the lockout or tagout
devices securing the machine or equipment are inserted
and which would be secured by a "job-lock" during multi-shift
SATELLITE LOCKBOX is a secondary
lockbox or lock-boxes to which each authorized employee
affixes his/her personal lock or tag.
MASTER TAG is a document used
as an administrative control and accountability device.
This device is normally controlled by the operations department
personnel and is a personal tagout device if each employee
personally signs on and signs off on it and if the tag
clearly identifies each authorized employee who is being
protected by it.
WORK PERMIT is a control document which authorizes specific
tasks and procedures to be accomplished.
Organization. A group lockout/tagout
procedure might provide the following basic organizational
A primary authorized employee
would be designated. This employee would exercise primary
responsibility for implementation and coordination of
the lockout/tagout of hazardous energy sources, for the
equipment to be serviced.
The primary authorized employee
would coordinate with equipment operators before and after
completion of servicing and maintenance operations which
A verification system would be
implemented to ensure the continued isolation and deenergization
of hazardous energy sources during maintenance and servicing
Each authorized employee would
be assured of his/her right to verify individually that
the hazardous energy has been isolated and/or deenergized.
When more than one crew, craft,
department, etc., is involved, each separate group of
servicing/ maintenance personnel would be accounted for
by a principal authorized employee from each group. Each
principal employee is responsible to the primary authorized
employee for maintaining accountability of each worker
in that specific group in conformance with the company
procedure. No person may sign on or sign off for another
person, or attach or remove another person's lockout/tagout
device, unless the provisions of the exception to 29 CFR
1910.147(e)(3) are met.
Examples of Procedures for Group
Lockout/Tagout. Examples are presented for the various methods
of lockout/tagout using lockbox procedures. An example of
an applicable method for complex process equipment is also
The following procedures address
circumstances ranging from a small group of servicing/
maintenance employees during a one-shift operation to
a comprehensive operation involving many over a longer
Type A. Each authorized employee
places his/her personal lock or tag upon each energy
isolating device and removes it upon departure from
that assignment. Each authorized employee verifies
or observes the deenergization of the equipment.
Type B. Under a lockbox procedure,
a lock or job-tag with tab is placed upon each energy
isolation device after deenergization. The key(s)
and removed tab(s) are then placed into a lockbox.
Each authorized employee assigned to the job then
affixes his/her personal lock or tag to the lockbox.
As a member of a group, each assigned authorized
employee verifies that all hazardous energy has
been rendered safe. The lockout/tagout devices cannot
be removed or the energy isolating device turned
on until the appropriate key or tab is matched to
its lock or tag.
Type C. After each energy isolating
device is locked/tagged out and the keys/tabs placed
into a master lockbox, each servicing/maintenance
group "principal" authorized employee places his/her
personal lock or tag upon the master lockbox. Then
each principal authorized employee inserts his/her
key into a satellite lockbox to which each authorized
employee in that specific group affixes his/her
personal lock or tag. As a member of a group, each
assigned authorized employee verifies that all hazardous
energy has been rendered safe. Only after the servicing/maintenance
functions of the specific subgroup have been concluded
and the personal locks or tags of the respective
employees have been removed from the satellite lockbox
can the principal authorized employee remove his/her
lock from the master lockbox.
Type D. During operations to
be conducted over more than one shift (or even many
days or weeks) a system such as described here might
be used. Single locks/tags are affixed upon a lockbox
by each authorized employee as described at Type
B or Type C above. The master lockbox is first secured
with a job-lock before subsequent locks by the principal
authorized employees are put in place on the master
lockbox. The job-lock may have multiple keys if
they are in the sole possession of the various primary
authorized employees (one on each shift). As a member
of a group, each assigned authorized employee verifies
that all hazardous energy has been rendered safe.
In this manner, the security provisions of the energy
control system are maintained across shift changes
while permitting reenergization of the equipment
at any appropriate time or shift.
Normal group lockout/tagout procedures
require the affixing of individual lockout/tagout devices
by each authorized employee to a group lockout device,
as discussed in paragraph B.3.a. of this appendix. However,
in the servicing and maintenance of sophisticated and
complex equipment, such as process equipment in petroleum
refining, petroleum production, and chemical production,
there may be a need for adaptation and modification of
normal group lockout/tagout procedures in order to ensure
the safety of the employees performing the servicing and
maintenance. To provide greater worker safety through
implementation of a more feasible system, and to accommodate
the special constraints of the standard's requirement
for ensuring employees a level of protection equivalent
to that provided by the use of a personal lockout or tagout
device, an alternative procedure may be implemented if
the company documentation justifies it. Lockout/ tagout,
blanking, blocking, etc., is often supplemented in these
situations by the use of work permits and a system of
continuous worker accountability. In evaluating whether
the equipment being serviced or maintained is so complex
as to necessitate a departure from the normal group lockout/tagout
procedures (discussed in paragraph B.3.a.), to the use
of an alternative procedure as set forth below, the following
(often occurring simultaneously) are some of those which
must be evaluated: physical size and extent of the equipment
being serviced/maintained; the relative inaccessibility
of the energy isolating devices; the number of employees
performing the servicing/maintenance; the number of energy
isolating devices to be locked/tagged out; and the interdependence
and interrelationship of the components in the system
or between different systems.
Once the equipment is shut down
and the hazardous energy has been controlled, maintenance/servicing
personnel, together with operations personnel, must
verify that the isolation of the equipment is effective.
The workers may walk through the affected work area
to verify isolation. If there is a potential for
the release or reaccumulation of hazardous energy,
verification ofisolation must be continued. The
servicing/maintenance workers may further verify
the effectiveness of the isolation by the procedures
that are used in doing the work (e.g., using a bleeder
valve to verify depressurization, flange-breaking
techniques, etc.). Throughout the maintenance and/or
servicing activity, operations personnel normally
maintain control of the equipment. The use of the
work permit or "master tag" system (with each employee
personally signing on and signing off the job to
ensure continual employee accountability and control),
combined with verification of hazardous energy control,
work procedures, and walk-through, is an acceptable
approach to compliance with the group lockout/tagout
and shift transfer provisions of the standard. (Note,
B.1.g. of this appendix.)
Specific issues related to the
control of hazardous energy in complex process equipment
are described below in a typical situation which
could be found at any facility. This discussion
is intended only as an example and is not anticipated
to reflect operations at any specific facility.
Complex process equipment
which is scheduled for servicing/maintenance
operations is generally identified by plant
supervision. Plant supervision would issue
specific work orders regarding the operations
to be performed.
In most instances where
complex process equipment is to be serviced
or maintained, the process equipment operators
can be expected to conduct the shutdown procedure.
This is generally due to their in-depth knowledge
of the equipment and the need to conduct the
shut-down procedure in a safe, economic and
The operations personnel
will normally prepare the equipment for lockout/tagout
as they proceed and will identify the locations
for blanks, blocks, etc., by placing "operations
locks and/or tags" on the equipment. The operations
personnel can be expected to isolate the hazardous
energy, and drain and flush fluids from the
process equipment following a standard procedure
or a specific work permit procedure.
Upon completion of shutdown,
the operations personnel would review the
intended job with the servicing and maintenance
crew(s) and would ensure their full comprehension
of the energy controls necessary to conduct
the servicing or maintenance safely. During
or immediately after the review of the job,
the servicing and maintenance crews would
install locks, tags and/or special isolating
devices at previously identified equipment
locations following the specified work permit
Line openings necessary
for the isolation of the equipment would normally
be permitted only by special work permits
issued by operations personnel. (Such line
openings should be monitored by operations
personnel as an added safety measure.)
All of the previous steps
should have been documented by a master system
of accountability and retained at the primary
equipment control station for the duration
of the job. The master system of accountability
may manifest itself as a Master Tag which
is subsequently signed by all of the maintenance/servicing
workers if they fully comprehend the details
of the job and the energy isolation devices
actuated or put in place. This signing by
the respective workers further verifies that
energy isolation training relative to this
operation has been conducted.
After the system has been
rendered safe, the authorized employees verify
energy controls as described in B.3.b.(1)
of this appendix.
Specific work functions
are controlled by work permits which are issued
for each shift. Each day each authorized employee
assigned must sign in on the work permit at
the time of arrival to the job and sign out
at departure. Signature, date, and time for
sign-in and sign-out would be recorded and
retained by the applicable crew supervisor
who upon completion of the permit requirements
would return the permit to the operations
supervisor. Work permits could extend beyond
a single shift and may subsequently be the
responsibility of several supervisors.
Upon completion of the
tasks required by the work permit, the authorized
employees' names can be signed off the Master
Tag by their supervisor once all employees
have signed off the work permit. The work
permit is then attached to the Master Tag.
(Accountability of exposed workers is maintained.)
As the work is completed
by the various crews, the work permits and
the accountability of personnel are reconciled
jointly by the primary authorized employee
and the operations supervisor.
During the progress of
the work, inspection audits are conducted.
Upon completion of all
work, the equipment is returned to the operations
personnel after the maintenance and servicing
crews have removed their locks, tags, and/or
special isolating devices following the company
At this time all authorized
employees who were assigned to the tasks are
again accounted for and verified to be clear
from the equipment area.
After the completion of
the servicing/ maintenance work, operations
personnel remove the tags originally placed
to identify energy isolation.
Operations personnel then
begin check-out, verification and testing
of the equipment prior to being returned to
It should be noted that the purpose
of the lockout/tagout standard is to reduce the likelihood
of worker injuries and fatalities during servicing/maintenance
operations. Therefore, when compliance officers inspect
workplaces, they should evaluate the potential for employee
exposure to the unexpected release of hazardous energy
during servicing/maintenance operations. When a hazard
is noted, the various requirements of the standard should
be applied in a manner which will result in abatement
of the hazardous circumstance.