29 Cfr 1910.146

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Title 29 → Subtitle B → Chapter XVII → Part 1910 → Subpart J → §1910.146
Title 29: Labor

PART 1910—OCCUPATIONAL SAFETY AND HEALTH STANDARDS

Subpart J—General Environmental Controls
§1910.146   Permit-required confined spaces.
(a) Scope and application. This section contains requirements for practices and
procedures to protect employees in general industry from the hazards of entry into permitrequired confined spaces. This section does not apply to agriculture, to construction, or to
shipyard employment (parts 1928, 1926, and 1915 of this chapter, respectively).
(b) Definitions.
Acceptable entry conditions means the conditions that must exist in a permit space to
allow entry and to ensure that employees involved with a permit-required confined space
entry can safely enter into and work within the space.
Attendant means an individual stationed outside one or more permit spaces who
monitors the authorized entrants and who performs all attendant's duties assigned in the
employer's permit space program.
Authorized entrant means an employee who is authorized by the employer to enter a
permit space.
Blanking or blinding means the absolute closure of a pipe, line, or duct by the fastening
of a solid plate (such as a spectacle blind or a skillet blind) that completely covers the bore
and that is capable of withstanding the maximum pressure of the pipe, line, or duct with no
leakage beyond the plate.
Confined space means a space that:
(1) Is large enough and so configured that an employee can bodily enter and perform
assigned work; and
(2) Has limited or restricted means for entry or exit (for example, tanks, vessels, silos,
storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.);
and
(3) Is not designed for continuous employee occupancy.
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Double block and bleed means the closure of a line, duct, or pipe by closing and locking
or tagging two in-line valves and by opening and locking or tagging a drain or vent valve in
the line between the two closed valves.
Emergency means any occurrence (including any failure of hazard control or monitoring
equipment) or event internal or external to the permit space that could endanger entrants.
Engulfment means the surrounding and effective capture of a person by a liquid or finely
divided (flowable) solid substance that can be aspirated to cause death by filling or plugging
the respiratory system or that can exert enough force on the body to cause death by
strangulation, constriction, or crushing.
Entry means the action by which a person passes through an opening into a permitrequired confined space. Entry includes ensuing work activities in that space and is
considered to have occurred as soon as any part of the entrant's body breaks the plane of an
opening into the space.
Entry permit (permit) means the written or printed document that is provided by the
employer to allow and control entry into a permit space and that contains the information
specified in paragraph (f) of this section.
Entry supervisor means the person (such as the employer, foreman, or crew chief)
responsible for determining if acceptable entry conditions are present at a permit space
where entry is planned, for authorizing entry and overseeing entry operations, and for
terminating entry as required by this section.
Note: An entry supervisor also may serve as an attendant or as an authorized entrant, as long
as that person is trained and equipped as required by this section for each role he or she fills. Also,
the duties of entry supervisor may be passed from one individual to another during the course of an
entry operation.

Hazardous atmosphere means an atmosphere that may expose employees to the risk of
death, incapacitation, impairment of ability to self-rescue (that is, escape unaided from a
permit space), injury, or acute illness from one or more of the following causes:
(1) Flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit
(LFL);
(2) Airborne combustible dust at a concentration that meets or exceeds its LFL;
Note: This concentration may be approximated as a condition in which the dust obscures vision
at a distance of 5 feet (1.52 m) or less.

(3) Atmospheric oxygen concentration below 19.5 percent or above 23.5 percent;
(4) Atmospheric concentration of any substance for which a dose or a permissible
exposure limit is published in subpart G, Occupational Health and Environmental Control, or
in subpart Z, Toxic and Hazardous Substances, of this part and which could result in
employee exposure in excess of its dose or permissible exposure limit;
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Note: An atmospheric concentration of any substance that is not capable of causing death,
incapacitation, impairment of ability to self-rescue, injury, or acute illness due to its health effects is
not covered by this provision.

(5) Any other atmospheric condition that is immediately dangerous to life or health.
Note: For air contaminants for which OSHA has not determined a dose or permissible exposure
limit, other sources of information, such as Material Safety Data Sheets that comply with the Hazard
Communication Standard, §1910.1200 of this part, published information, and internal documents
can provide guidance in establishing acceptable atmospheric conditions.

Hot work permit means the employer's written authorization to perform operations (for
example, riveting, welding, cutting, burning, and heating) capable of providing a source of
ignition.
Immediately dangerous to life or health (IDLH) means any condition that poses an
immediate or delayed threat to life or that would cause irreversible adverse health effects or
that would interfere with an individual's ability to escape unaided from a permit space.
Note: Some materials—hydrogen fluoride gas and cadmium vapor, for example—may produce
immediate transient effects that, even if severe, may pass without medical attention, but are followed
by sudden, possibly fatal collapse 12-72 hours after exposure. The victim “feels normal” from
recovery from transient effects until collapse. Such materials in hazardous quantities are considered
to be “immediately” dangerous to life or health.

Inerting means the displacement of the atmosphere in a permit space by a
noncombustible gas (such as nitrogen) to such an extent that the resulting atmosphere is
noncombustible.
Note: This procedure produces an IDLH oxygen-deficient atmosphere.

Isolation means the process by which a permit space is removed from service and
completely protected against the release of energy and material into the space by such
means as: blanking or blinding; misaligning or removing sections of lines, pipes, or ducts; a
double block and bleed system; lockout or tagout of all sources of energy; or blocking or
disconnecting all mechanical linkages.
Line breaking means the intentional opening of a pipe, line, or duct that is or has been
carrying flammable, corrosive, or toxic material, an inert gas, or any fluid at a volume,
pressure, or temperature capable of causing injury.
Non-permit confined space means a confined space that does not contain or, with
respect to atmospheric hazards, have the potential to contain any hazard capable of causing
death or serious physical harm.
Oxygen deficient atmosphere means an atmosphere containing less than 19.5 percent
oxygen by volume.
Oxygen enriched atmosphere means an atmosphere containing more than 23.5 percent
oxygen by volume.
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Permit-required confined space (permit space) means a confined space that has one or
more of the following characteristics:
(1) Contains or has a potential to contain a hazardous atmosphere;
(2) Contains a material that has the potential for engulfing an entrant;
(3) Has an internal configuration such that an entrant could be trapped or asphyxiated by
inwardly converging walls or by a floor which slopes downward and tapers to a smaller crosssection; or
(4) Contains any other recognized serious safety or health hazard.
Permit-required confined space program (permit space program) means the employer's
overall program for controlling, and, where appropriate, for protecting employees from, permit
space hazards and for regulating employee entry into permit spaces.
Permit system means the employer's written procedure for preparing and issuing permits
for entry and for returning the permit space to service following termination of entry.
Prohibited condition means any condition in a permit space that is not allowed by the
permit during the period when entry is authorized.
Rescue service means the personnel designated to rescue employees from permit
spaces.
Retrieval system means the equipment (including a retrieval line, chest or full-body
harness, wristlets, if appropriate, and a lifting device or anchor) used for non-entry rescue of
persons from permit spaces.
Testing means the process by which the hazards that may confront entrants of a permit
space are identified and evaluated. Testing includes specifying the tests that are to be
performed in the permit space.
Note: Testing enables employers both to devise and implement adequate control measures for
the protection of authorized entrants and to determine if acceptable entry conditions are present
immediately prior to, and during, entry.

(c) General requirements. (1) The employer shall evaluate the workplace to determine if
any spaces are permit- required confined spaces.
Note: Proper application of the decision flow chart in appendix A to §1910.146 would facilitate
compliance with this requirement.

(2) If the workplace contains permit spaces, the employer shall inform exposed
employees, by posting danger signs or by any other equally effective means, of the existence
and location of and the danger posed by the permit spaces.
Note: A sign reading “DANGER—PERMIT-REQUIRED CONFINED SPACE, DO NOT ENTER”
or using other similar language would satisfy the requirement for a sign.
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ou d sat s y t e equ e e t o a s g

(3) If the employer decides that its employees will not enter permit spaces, the employer
shall take effective measures to prevent its employees from entering the permit spaces and
shall comply with paragraphs (c)(1), (c)(2), (c)(6), and (c)(8) of this section.
(4) If the employer decides that its employees will enter permit spaces, the employer
shall develop and implement a written permit space program that complies with this section.
The written program shall be available for inspection by employees and their authorized
representatives.
(5) An employer may use the alternate procedures specified in paragraph (c)(5)(ii) of this
section for entering a permit space under the conditions set forth in paragraph (c)(5)(i) of this
section.
(i) An employer whose employees enter a permit space need not comply with
paragraphs (d) through (f) and (h) through (k) of this section, provided that:
(A) The employer can demonstrate that the only hazard posed by the permit space is an
actual or potential hazardous atmosphere;
(B) The employer can demonstrate that continuous forced air ventilation alone is
sufficient to maintain that permit space safe for entry;
(C) The employer develops monitoring and inspection data that supports the
demonstrations required by paragraphs (c)(5)(i)(A) and (c)(5)(i)(B) of this section;
(D) If an initial entry of the permit space is necessary to obtain the data required by
paragraph (c)(5)(i)(C) of this section, the entry is performed in compliance with paragraphs
(d) through (k) of this section;
(E) The determinations and supporting data required by paragraphs (c)(5)(i)(A), (c)(5)(i)
(B), and (c)(5)(i)(C) of this section are documented by the employer and are made available
to each employee who enters the permit space under the terms of paragraph (c)(5) of this
section or to that employee's authorized representative; and
(F) Entry into the permit space under the terms of paragraph (c)(5)(i) of this section is
performed in accordance with the requirements of paragraph (c)(5)(ii) of this section.
Note: See paragraph (c)(7) of this section for reclassification of a permit space after all hazards
within the space have been eliminated.

(ii) The following requirements apply to entry into permit spaces that meet the conditions
set forth in paragraph (c)(5)(i) of this section.
(A) Any conditions making it unsafe to remove an entrance cover shall be eliminated
before the cover is removed.
(B) When entrance covers are removed, the opening shall be promptly guarded by a
railing, temporary cover, or other temporary barrier that will prevent an accidental fall through
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the opening and that will protect each employee working in the space from foreign objects
entering the space.
(C) Before an employee enters the space, the internal atmosphere shall be tested, with a
calibrated direct-reading instrument, for oxygen content, for flammable gases and vapors,
and for potential toxic air contaminants, in that order. Any employee who enters the space, or
that employee's authorized representative, shall be provided an opportunity to observe the
pre-entry testing required by this paragraph.
(D) There may be no hazardous atmosphere within the space whenever any employee
is inside the space.
(E) Continuous forced air ventilation shall be used, as follows:
(1) An employee may not enter the space until the forced air ventilation has eliminated
any hazardous atmosphere;
(2) The forced air ventilation shall be so directed as to ventilate the immediate areas
where an employee is or will be present within the space and shall continue until all
employees have left the space;
(3) The air supply for the forced air ventilation shall be from a clean source and may not
increase the hazards in the space.
(F) The atmosphere within the space shall be periodically tested as necessary to ensure
that the continuous forced air ventilation is preventing the accumulation of a hazardous
atmosphere. Any employee who enters the space, or that employee's authorized
representative, shall be provided with an opportunity to observe the periodic testing required
by this paragraph.
(G) If a hazardous atmosphere is detected during entry:
(1) Each employee shall leave the space immediately;
(2) The space shall be evaluated to determine how the hazardous atmosphere
developed; and
(3) Measures shall be implemented to protect employees from the hazardous
atmosphere before any subsequent entry takes place.
(H) The employer shall verify that the space is safe for entry and that the pre-entry
measures required by paragraph (c)(5)(ii) of this section have been taken, through a written
certification that contains the date, the location of the space, and the signature of the person
providing the certification. The certification shall be made before entry and shall be made
available to each employee entering the space or to that employee's authorized
representative .

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(6) When there are changes in the use or configuration of a non-permit confined space
that might increase the hazards to entrants, the employer shall reevaluate that space and, if
necessary, reclassify it as a permit-required confined space.
(7) A space classified by the employer as a permit-required confined space may be
reclassified as a non-permit confined space under the following procedures:
(i) If the permit space poses no actual or potential atmospheric hazards and if all
hazards within the space are eliminated without entry into the space, the permit space may
be reclassified as a non-permit confined space for as long as the non-atmospheric hazards
remain eliminated.
(ii) If it is necessary to enter the permit space to eliminate hazards, such entry shall be
performed under paragraphs (d) through (k) of this section. If testing and inspection during
that entry demonstrate that the hazards within the permit space have been eliminated, the
permit space may be reclassified as a non-permit confined space for as long as the hazards
remain eliminated.
Note: Control of atmospheric hazards through forced air ventilation does not constitute
elimination of the hazards. Paragraph (c)(5) covers permit space entry where the employer can
demonstrate that forced air ventilation alone will control all hazards in the space.

(iii) The employer shall document the basis for determining that all hazards in a permit
space have been eliminated, through a certification that contains the date, the location of the
space, and the signature of the person making the determination. The certification shall be
made available to each employee entering the space or to that employee's authorized
representative.
(iv) If hazards arise within a permit space that has been declassified to a non-permit
space under paragraph (c)(7) of this section, each employee in the space shall exit the
space. The employer shall then reevaluate the space and determine whether it must be
reclassified as a permit space, in accordance with other applicable provisions of this section.
(8) When an employer (host employer) arranges to have employees of another employer
(contractor) perform work that involves permit space entry, the host employer shall:
(i) Inform the contractor that the workplace contains permit spaces and that permit space
entry is allowed only through compliance with a permit space program meeting the
requirements of this section;
(ii) Apprise the contractor of the elements, including the hazards identified and the host
employer's experience with the space, that make the space in question a permit space;
(iii) Apprise the contractor of any precautions or procedures that the host employer has
implemented for the protection of employees in or near permit spaces where contractor
personnel will be working;
(iv) Coordinate entry operations with the contractor, when both host employer personnel
and contractor personnel will be working in or near permit spaces as required by paragraph

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and contractor personnel will be working in or near permit spaces, as required by paragraph
(d)(11) of this section; and
(v) Debrief the contractor at the conclusion of the entry operations regarding the permit
space program followed and regarding any hazards confronted or created in permit spaces
during entry operations.
(9) In addition to complying with the permit space requirements that apply to all
employers, each contractor who is retained to perform permit space entry operations shall:
(i) Obtain any available information regarding permit space hazards and entry operations
from the host employer;
(ii) Coordinate entry operations with the host employer, when both host employer
personnel and contractor personnel will be working in or near permit spaces, as required by
paragraph (d)(11) of this section; and
(iii) Inform the host employer of the permit space program that the contractor will follow
and of any hazards confronted or created in permit spaces, either through a debriefing or
during the entry operation.
(d) Permit-required confined space program (permit space program). Under the permit
space program required by paragraph (c)(4) of this section, the employer shall:
(1) Implement the measures necessary to prevent unauthorized entry;
(2) Identify and evaluate the hazards of permit spaces before employees enter them;
(3) Develop and implement the means, procedures, and practices necessary for safe
permit space entry operations, including, but not limited to, the following:
(i) Specifying acceptable entry conditions;
(ii) Providing each authorized entrant or that employee's authorized representative with
the opportunity to observe any monitoring or testing of permit spaces;
(iii) Isolating the permit space;
(iv) Purging, inerting, flushing, or ventilating the permit space as necessary to eliminate
or control atmospheric hazards;
(v) Providing pedestrian, vehicle, or other barriers as necessary to protect entrants from
external hazards; and
(vi) Verifying that conditions in the permit space are acceptable for entry throughout the
duration of an authorized entry.
(4) Provide the following equipment (specified in paragraphs (d)(4)(i) through (d)(4)(ix) of
this section) at no cost to employees, maintain that equipment properly, and ensure that
employees use that equipment properly:

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(i) Testing and monitoring equipment needed to comply with paragraph (d)(5) of this
section;
(ii) Ventilating equipment needed to obtain acceptable entry conditions;
(iii) Communications equipment necessary for compliance with paragraphs (h)(3) and (i)
(5) of this section;
(iv) Personal protective equipment insofar as feasible engineering and work practice
controls do not adequately protect employees;
(v) Lighting equipment needed to enable employees to see well enough to work safely
and to exit the space quickly in an emergency;
(vi) Barriers and shields as required by paragraph (d)(3)(v) of this section.
(vii) Equipment, such as ladders, needed for safe ingress and egress by authorized
entrants;
(viii) Rescue and emergency equipment needed to comply with paragraph (d)(9) of this
section, except to the extent that the equipment is provided by rescue services; and
(ix) Any other equipment necessary for safe entry into and rescue from permit spaces.
(5) Evaluate permit space conditions as follows when entry operations are conducted:
(i) Test conditions in the permit space to determine if acceptable entry conditions exist
before entry is authorized to begin, except that, if isolation of the space is infeasible because
the space is large or is part of a continuous system (such as a sewer), pre-entry testing shall
be performed to the extent feasible before entry is authorized and, if entry is authorized, entry
conditions shall be continuously monitored in the areas where authorized entrants are
working;
(ii) Test or monitor the permit space as necessary to determine if acceptable entry
conditions are being maintained during the course of entry operations; and
(iii) When testing for atmospheric hazards, test first for oxygen, then for combustible
gases and vapors, and then for toxic gases and vapors.
(iv) Provide each authorized entrant or that employee's authorized representative an
opportunity to observe the pre-entry and any subsequent testing or monitoring of permit
spaces;
(v) Reevaluate the permit space in the presence of any authorized entrant or that
employee's authorized representative who requests that the employer conduct such
reevaluation because the entrant or representative has reason to believe that the evaluation
of that space may not have been adequate;
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(vi) Immediately provide each authorized entrant or that employee's authorized
representative with the results of any testing conducted in accord with paragraph (d) of this
section.
Note: Atmospheric testing conducted in accordance with appendix B to §1910.146 would be
considered as satisfying the requirements of this paragraph. For permit space operations in sewers,
atmospheric testing conducted in accordance with appendix B, as supplemented by appendix E to
§1910.146, would be considered as satisfying the requirements of this paragraph.

(6) Provide at least one attendant outside the permit space into which entry is authorized
for the duration of entry operations;
Note: Attendants may be assigned to monitor more than one permit space provided the duties
described in paragraph (i) of this section can be effectively performed for each permit space that is
monitored. Likewise, attendants may be stationed at any location outside the permit space to be
monitored as long as the duties described in paragraph (i) of this section can be effectively
performed for each permit space that is monitored.

(7) If multiple spaces are to be monitored by a single attendant, include in the permit
program the means and procedures to enable the attendant to respond to an emergency
affecting one or more of the permit spaces being monitored without distraction from the
attendant's responsibilities under paragraph (i) of this section;
(8) Designate the persons who are to have active roles (as, for example, authorized
entrants, attendants, entry supervisors, or persons who test or monitor the atmosphere in a
permit space) in entry operations, identify the duties of each such employee, and provide
each such employee with the training required by paragraph (g) of this section;
(9) Develop and implement procedures for summoning rescue and emergency services,
for rescuing entrants from permit spaces, for providing necessary emergency services to
rescued employees, and for preventing unauthorized personnel from attempting a rescue;
(10) Develop and implement a system for the preparation, issuance, use, and
cancellation of entry permits as required by this section;
(11) Develop and implement procedures to coordinate entry operations when employees
of more than one employer are working simultaneously as authorized entrants in a permit
space, so that employees of one employer do not endanger the employees of any other
employer;
(12) Develop and implement procedures (such as closing off a permit space and
canceling the permit) necessary for concluding the entry after entry operations have been
completed;
(13) Review entry operations when the employer has reason to believe that the
measures taken under the permit space program may not protect employees and revise the
program to correct deficiencies found to exist before subsequent entries are authorized; and
Note: Examples of circumstances requiring the review of the permit space program are: any
unauthorized entry of a permit space the detection of a permit space hazard not covered by the

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unauthorized entry of a permit space, the detection of a permit space hazard not covered by the
permit, the detection of a condition prohibited by the permit, the occurrence of an injury or near-miss
during entry, a change in the use or configuration of a permit space, and employee complaints about
the effectiveness of the program.

(14) Review the permit space program, using the canceled permits retained under
paragraph (e)(6) of this section within 1 year after each entry and revise the program as
necessary, to ensure that employees participating in entry operations are protected from
permit space hazards.
Note: Employers may perform a single annual review covering all entries performed during a
12-month period. If no entry is performed during a 12-month period, no review is necessary.
Appendix C to §1910.146 presents examples of permit space programs that are considered to
comply with the requirements of paragraph (d) of this section.

(e) Permit system. (1) Before entry is authorized, the employer shall document the
completion of measures required by paragraph (d)(3) of this section by preparing an entry
permit.
Note: Appendix D to §1910.146 presents examples of permits whose elements are considered
to comply with the requirements of this section.

(2) Before entry begins, the entry supervisor identified on the permit shall sign the entry
permit to authorize entry.
(3) The completed permit shall be made available at the time of entry to all authorized
entrants or their authorized representatives, by posting it at the entry portal or by any other
equally effective means, so that the entrants can confirm that pre-entry preparations have
been completed.
(4) The duration of the permit may not exceed the time required to complete the
assigned task or job identified on the permit in accordance with paragraph (f)(2) of this
section.
(5) The entry supervisor shall terminate entry and cancel the entry permit when:
(i) The entry operations covered by the entry permit have been completed; or
(ii) A condition that is not allowed under the entry permit arises in or near the permit
space.
(6) The employer shall retain each canceled entry permit for at least 1 year to facilitate
the review of the permit-required confined space program required by paragraph (d)(14) of
this section. Any problems encountered during an entry operation shall be noted on the
pertinent permit so that appropriate revisions to the permit space program can be made.
(f) Entry permit. The entry permit that documents compliance with this section and
authorizes entry to a permit space shall identify:
(1) The permit space to be entered;
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(2) The purpose of the entry;
(3) The date and the authorized duration of the entry permit;
(4) The authorized entrants within the permit space, by name or by such other means
(for example, through the use of rosters or tracking systems) as will enable the attendant to
determine quickly and accurately, for the duration of the permit, which authorized entrants
are inside the permit space;
Note: This requirement may be met by inserting a reference on the entry permit as to the
means used, such as a roster or tracking system, to keep track of the authorized entrants within the
permit space.

(5) The personnel, by name, currently serving as attendants;
(6) The individual, by name, currently serving as entry supervisor, with a space for the
signature or initials of the entry supervisor who originally authorized entry;
(7) The hazards of the permit space to be entered;
(8) The measures used to isolate the permit space and to eliminate or control permit
space hazards before entry;
Note: Those measures can include the lockout or tagging of equipment and procedures for
purging, inerting, ventilating, and flushing permit spaces.

(9) The acceptable entry conditions;
(10) The results of initial and periodic tests performed under paragraph (d)(5) of this
section, accompanied by the names or initials of the testers and by an indication of when the
tests were performed;
(11) The rescue and emergency services that can be summoned and the means (such
as the equipment to use and the numbers to call) for summoning those services;
(12) The communication procedures used by authorized entrants and attendants to
maintain contact during the entry;
(13) Equipment, such as personal protective equipment, testing equipment,
communications equipment, alarm systems, and rescue equipment, to be provided for
compliance with this section;
(14) Any other information whose inclusion is necessary, given the circumstances of the
particular confined space, in order to ensure employee safety; and
(15) Any additional permits, such as for hot work, that have been issued to authorize
work in the permit space.
(g) Training. (1) The employer shall provide training so that all employees whose work is
regulated by this section acquire the understanding, knowledge, and skills necessary for the
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regulated by this section acquire the understanding, knowledge, and skills necessary for the
safe performance of the duties assigned under this section.
(2) Training shall be provided to each affected employee:
(i) Before the employee is first assigned duties under this section;
(ii) Before there is a change in assigned duties;
(iii) Whenever there is a change in permit space operations that presents a hazard about
which an employee has not previously been trained;
(iv) Whenever the employer has reason to believe either that there are deviations from
the permit space entry procedures required by paragraph (d)(3) of this section or that there
are inadequacies in the employee's knowledge or use of these procedures.
(3) The training shall establish employee proficiency in the duties required by this section
and shall introduce new or revised procedures, as necessary, for compliance with this
section.
(4) The employer shall certify that the training required by paragraphs (g)(1) through (g)
(3) of this section has been accomplished. The certification shall contain each employee's
name, the signatures or initials of the trainers, and the dates of training. The certification shall
be available for inspection by employees and their authorized representatives.
(h) Duties of authorized entrants. The employer shall ensure that all authorized entrants:
(1) Know the hazards that may be faced during entry, including information on the mode,
signs or symptoms, and consequences of the exposure;
(2) Properly use equipment as required by paragraph (d)(4) of this section;
(3) Communicate with the attendant as necessary to enable the attendant to monitor
entrant status and to enable the attendant to alert entrants of the need to evacuate the space
as required by paragraph (i)(6) of this section;
(4) Alert the attendant whenever:
(i) The entrant recognizes any warning sign or symptom of exposure to a dangerous
situation, or
(ii) The entrant detects a prohibited condition; and
(5) Exit from the permit space as quickly as possible whenever:
(i) An order to evacuate is given by the attendant or the entry supervisor,
(ii) The entrant recognizes any warning sign or symptom of exposure to a dangerous
situation,

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(iii) The entrant detects a prohibited condition, or
(iv) An evacuation alarm is activated.
(i) Duties of attendants. The employer shall ensure that each attendant:
(1) Knows the hazards that may be faced during entry, including information on the
mode, signs or symptoms, and consequences of the exposure;
(2) Is aware of possible behavioral effects of hazard exposure in authorized entrants;
(3) Continuously maintains an accurate count of authorized entrants in the permit space
and ensures that the means used to identify authorized entrants under paragraph (f)(4) of
this section accurately identifies who is in the permit space;
(4) Remains outside the permit space during entry operations until relieved by another
attendant;
Note: When the employer's permit entry program allows attendant entry for rescue, attendants
may enter a permit space to attempt a rescue if they have been trained and equipped for rescue
operations as required by paragraph (k)(1) of this section and if they have been relieved as required
by paragraph (i)(4) of this section.

(5) Communicates with authorized entrants as necessary to monitor entrant status and
to alert entrants of the need to evacuate the space under paragraph (i)(6) of this section;
(6) Monitors activities inside and outside the space to determine if it is safe for entrants
to remain in the space and orders the authorized entrants to evacuate the permit space
immediately under any of the following conditions;
(i) If the attendant detects a prohibited condition;
(ii) If the attendant detects the behavioral effects of hazard exposure in an authorized
entrant;
(iii) If the attendant detects a situation outside the space that could endanger the
authorized entrants; or
(iv) If the attendant cannot effectively and safely perform all the duties required under
paragraph (i) of this section;
(7) Summon rescue and other emergency services as soon as the attendant determines
that authorized entrants may need assistance to escape from permit space hazards;
(8) Takes the following actions when unauthorized persons approach or enter a permit
space while entry is underway:
(i) Warn the unauthorized persons that they must stay away from the permit space;
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(ii) Advise the unauthorized persons that they must exit immediately if they have entered
the permit space; and
(iii) Inform the authorized entrants and the entry supervisor if unauthorized persons have
entered the permit space;
(9) Performs non-entry rescues as specified by the employer's rescue procedure; and
(10) Performs no duties that might interfere with the attendant's primary duty to monitor
and protect the authorized entrants.
(j) Duties of entry supervisors. The employer shall ensure that each entry supervisor:
(1) Knows the hazards that may be faced during entry, including information on the
mode, signs or symptoms, and consequences of the exposure;
(2) Verifies, by checking that the appropriate entries have been made on the permit, that
all tests specified by the permit have been conducted and that all procedures and equipment
specified by the permit are in place before endorsing the permit and allowing entry to begin;
(3) Terminates the entry and cancels the permit as required by paragraph (e)(5) of this
section;
(4) Verifies that rescue services are available and that the means for summoning them
are operable;
(5) Removes unauthorized individuals who enter or who attempt to enter the permit
space during entry operations; and
(6) Determines, whenever responsibility for a permit space entry operation is transferred
and at intervals dictated by the hazards and operations performed within the space, that
entry operations remain consistent with terms of the entry permit and that acceptable entry
conditions are maintained.
(k) Rescue and emergency services. (1) An employer who designates rescue and
emergency services, pursuant to paragraph (d)(9) of this section, shall:
(i) Evaluate a prospective rescuer's ability to respond to a rescue summons in a timely
manner, considering the hazard(s) identified;
Note to paragraph (k)(1)(i): What will be considered timely will vary according to the specific
hazards involved in each entry. For example, §1910.134, Respiratory Protection, requires that
employers provide a standby person or persons capable of immediate action to rescue employee(s)
wearing respiratory protection while in work areas defined as IDLH atmospheres.

(ii) Evaluate a prospective rescue service's ability, in terms of proficiency with rescuerelated tasks and equipment, to function appropriately while rescuing entrants from the
particular permit space or types of permit spaces identified;
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(iii) Select a rescue team or service from those evaluated that:
(A) Has the capability to reach the victim(s) within a time frame that is appropriate for the
permit space hazard(s) identified;
(B) Is equipped for and proficient in performing the needed rescue services;
(iv) Inform each rescue team or service of the hazards they may confront when called on
to perform rescue at the site; and
(v) Provide the rescue team or service selected with access to all permit spaces from
which rescue may be necessary so that the rescue service can develop appropriate rescue
plans and practice rescue operations.
Note to paragraph (k)(1): Non-mandatory appendix F contains examples of criteria which
employers can use in evaluating prospective rescuers as required by paragraph (k)(1) of this section.

(2) An employer whose employees have been designated to provide permit space
rescue and emergency services shall take the following measures:
(i) Provide affected employees with the personal protective equipment (PPE) needed to
conduct permit space rescues safely and train affected employees so they are proficient in
the use of that PPE, at no cost to those employees;
(ii) Train affected employees to perform assigned rescue duties. The employer must
ensure that such employees successfully complete the training required to establish
proficiency as an authorized entrant, as provided by paragraphs (g) and (h) of this section;
(iii) Train affected employees in basic first-aid and cardiopulmonary resuscitation (CPR).
The employer shall ensure that at least one member of the rescue team or service holding a
current certification in first aid and CPR is available; and
(iv) Ensure that affected employees practice making permit space rescues at least once
every 12 months, by means of simulated rescue operations in which they remove dummies,
manikins, or actual persons from the actual permit spaces or from representative permit
spaces. Representative permit spaces shall, with respect to opening size, configuration, and
accessibility, simulate the types of permit spaces from which rescue is to be performed.
(3) To facilitate non-entry rescue, retrieval systems or methods shall be used whenever
an authorized entrant enters a permit space, unless the retrieval equipment would increase
the overall risk of entry or would not contribute to the rescue of the entrant. Retrieval systems
shall meet the following requirements.
(i) Each authorized entrant shall use a chest or full body harness, with a retrieval line
attached at the center of the entrant's back near shoulder level, above the entrant's head, or
at another point which the employer can establish presents a profile small enough for the
successful removal of the entrant. Wristlets may be used in lieu of the chest or full body
harness if the employer can demonstrate that the use of a chest or full body harness is
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infeasible or creates a greater hazard and that the use of wristlets is the safest and most
effective alternative.
(ii) The other end of the retrieval line shall be attached to a mechanical device or fixed
point outside the permit space in such a manner that rescue can begin as soon as the
rescuer becomes aware that rescue is necessary. A mechanical device shall be available to
retrieve personnel from vertical type permit spaces more than 5 feet (1.52 m) deep.
(4) If an injured entrant is exposed to a substance for which a Material Safety Data
Sheet (MSDS) or other similar written information is required to be kept at the worksite, that
MSDS or written information shall be made available to the medical facility treating the
exposed entrant.
(l) Employee participation. (1) Employers shall consult with affected employees and their
authorized representatives on the development and implementation of all aspects of the
permit space program required by paragraph (c) of this section.
(2) Employers shall make available to affected employees and their authorized
representatives all information required to be developed by this section.
Appendixes to §1910.146—Permit-required Confined Spaces
Note: Appendixes A through F serve to provide information and non-mandatory guidelines to
assist employers and employees in complying with the appropriate requirements of this section.

Appendix A to §1910.146—Permit-Required Confined Space Decision Flow Chart

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View or download PDF
Appendix B to §1910.146—Procedures for Atmospheric Testing
Atmospheric testing is required for two distinct purposes: evaluation of the hazards of the permit space
and verification that acceptable entry conditions for entry into that space exist.
(1) Evaluation testing. The atmosphere of a confined space should be analyzed using equipment of
sufficient sensitivity and specificity to identify and evaluate any hazardous atmospheres that may exist or
arise, so that appropriate permit entry procedures can be developed and acceptable entry conditions
stipulated for that space. Evaluation and interpretation of these data, and development of the entry procedure,
should be done by, or reviewed by, a technically qualified professional (e.g., OSHA consultation service, or
certified industrial hygienist, registered safety engineer, certified safety professional, certified marine chemist,
etc.) based on evaluation of all serious hazards.
(2) Verification testing. The atmosphere of a permit space which may contain a hazardous atmosphere
should be tested for residues of all contaminants identified by evaluation testing using permit specified
equipment to determine that residual concentrations at the time of testing and entry are within the range of
acceptable entry conditions. Results of testing (i.e., actual concentration, etc.) should be recorded on the
permit in the space provided adjacent to the stipulated acceptable entry condition.
(3) Duration of testing. Measurement of values for each atmospheric parameter should be made for at
least the minimum response time of the test instrument specified by the manufacturer.
(4) Testing stratified atmospheres. When monitoring for entries involving a descent into atmospheres that
may be stratified, the atmospheric envelope should be tested a distance of approximately 4 feet (1.22 m) in
the direction of travel and to each side. If a sampling probe is used, the entrant's rate of progress should be
slowed to accommodate the sampling speed and detector response.
(5) Order of testing. A test for oxygen is performed first because most combustible gas meters are oxygen
dependent and will not provide reliable readings in an oxygen deficient atmosphere. Combustible gasses are
tested for next because the threat of fire or explosion is both more immediate and more life threatening, in
most cases, than exposure to toxic gasses and vapors. If tests for toxic gasses and vapors are necessary,
they are performed last.

Appendix C to §1910.146—Examples of Permit-required Confined Space Programs
Example 1.
Workplace. Sewer entry.
Potential hazards. The employees could be exposed to the following:
Engulfment.
Presence of toxic gases. Equal to or more than 10 ppm hydrogen sulfide measured as an 8-hour timeweighted average. If the presence of other toxic contaminants is suspected, specific monitoring programs will
be developed.
Presence of explosive/flammable gases. Equal to or greater than 10% of the lower flammable limit (LFL).
Oxygen Deficiency. A concentration of oxygen in the atmosphere equal to or less than 19.5% by volume.
A. Entry Without Permit/Attendant
Certification. Confined spaces may be entered without the need for a written permit or attendant provided that
the space can be maintained in a safe condition for entry by mechanical ventilation alone, as provided in
§1910.146(c)(5). All spaces shall be considered permit-required confined spaces until the pre-entry
procedures demonstrate otherwise. Any employee required or permitted to pre-check or enter an
enclosed/confined space shall have successfully completed, -as a minimum, the training as required by the
following sections of these procedures. A written copy of operating and rescue procedures as required by
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y

g

y

these procedures shall be at the work site for the duration of the job. The Confined Space Pre-Entry Check
List must be completed by the LEAD WORKER before entry into a confined space. This list verifies
completion of items listed below. This check list shall be kept at the job site for duration of the job. If
circumstances dictate an interruption in the work, the permit space must be re-evaluated and a new check list
must be completed.
Control of atmospheric and engulfment hazards.
Pumps and Lines. All pumps and lines which may reasonably cause contaminants to flow into the space shall
be disconnected, blinded and locked out, or effectively isolated by other means to prevent development of
dangerous air contamination or engulfment. Not all laterals to sewers or storm drains require blocking.
However, where experience or knowledge of industrial use indicates there is a reasonable potential for
contamination of air or engulfment into an occupied sewer, then all affected laterals shall be blocked. If
blocking and/or isolation requires entry into the space the provisions for entry into a permit- required confined
space must be implemented.
Surveillance. The surrounding area shall be surveyed to avoid hazards such as drifting vapors from the tanks,
piping, or sewers.
Testing. The atmosphere within the space will be tested to determine whether dangerous air contamination
and/or oxygen deficiency exists. Detector tubes, alarm only gas monitors and explosion meters are examples
of monitoring equipment that may be used to test permit space atmospheres. Testing shall be performed by
the LEAD WORKER who has successfully completed the Gas Detector training for the monitor he will use.
The minimum parameters to be monitored are oxygen deficiency, LFL, and hydrogen sulfide concentration. A
written record of the pre-entry test results shall be made and kept at the work site for the duration of the job.
The supervisor will certify in writing, based upon the results of the pre-entry testing, that all hazards have been
eliminated. Affected employees shall be able to review the testing results. The most hazardous conditions
shall govern when work is being performed in two adjoining, connecting spaces.
Entry Procedures. If there are no non-atmospheric hazards present and if the pre-entry tests show there is no
dangerous air contamination and/or oxygen deficiency within the space and there is no reason to believe that
any is likely to develop, entry into and work within may proceed. Continuous testing of the atmosphere in the
immediate vicinity of the workers within the space shall be accomplished. The workers will immediately leave
the permit space when any of the gas monitor alarm set points are reached as defined. Workers will not return
to the area until a SUPERVISOR who has completed the gas detector training has used a direct reading gas
detector to evaluate the situation and has determined that it is safe to enter.
Rescue. Arrangements for rescue services are not required where there is no attendant. See the rescue
portion of section B., below, for instructions regarding rescue planning where an entry permit is required.
B. Entry Permit Required
Permits. Confined Space Entry Permit. All spaces shall be considered permit-required confined spaces until
the pre-entry procedures demonstrate otherwise. Any employee required or permitted to pre-check or enter a
permit-required confined space shall have successfully completed, as a minimum, the training as required by
the following sections of these procedures. A written copy of operating and rescue procedures as required by
these procedures shall be at the work site for the duration of the job. The Confined Space Entry Permit must
be completed before approval can be given to enter a permit-required confined space. This permit verifies
completion of items listed below. This permit shall be kept at the job site for the duration of the job. If
circumstances cause an interruption in the work or a change in the alarm conditions for which entry was
approved, a new Confined Space Entry Permit must be completed.
Control of atmospheric and engulfment hazards.
Surveillance. The surrounding area shall be surveyed to avoid hazards such as drifting vapors from tanks,
piping or sewers.
Testing. The confined space atmosphere shall be tested to determine whether dangerous air contamination
and/or oxygen deficiency exists. A direct reading gas monitor shall be used. Testing shall be performed by the
SUPERVISOR who has successfully completed the gas detector training for the monitor he will use. The
minimum parameters to be monitored are oxygen deficiency, LFL and hydrogen sulfide concentration. A
written record of the pre- entry test results shall be made and kept at the work site for the duration of the job

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written record of the pre- entry test results shall be made and kept at the work site for the duration of the job.
Affected employees shall be able to review the testing results. The most hazardous conditions shall govern
when work is being performed in two adjoining, connected spaces.
Space Ventilation. Mechanical ventilation systems, where applicable, shall be set at 100% outside air. Where
possible, open additional manholes to increase air circulation. Use portable blowers to augment natural
circulation if needed. After a suitable ventilating period, repeat the testing. Entry may not begin until testing
has demonstrated that the hazardous atmosphere has been eliminated.
Entry Procedures. The following procedure shall be observed under any of the following conditions: 1.) Testing
demonstrates the existence of dangerous or deficient conditions and additional ventilation cannot reduce
concentrations to safe levels; 2.) The atmosphere tests as safe but unsafe conditions can reasonably be
expected to develop; 3.) It is not feasible to provide for ready exit from spaces equipped with automatic fire
suppression systems and it is not practical or safe to deactivate such systems; or 4.) An emergency exists and
it is not feasible to wait for pre-entry procedures to take effect.
All personnel must be trained. A self contained breathing apparatus shall be worn by any person entering
the space. At least one worker shall stand by the outside of the space ready to give assistance in case of
emergency. The standby worker shall have a self contained breathing apparatus available for immediate use.
There shall be at least one additional worker within sight or call of the standby worker. Continuous powered
communications shall be maintained between the worker within the confined space and standby personnel.
If at any time there is any questionable action or non- movement by the worker inside, a verbal check will
be made. If there is no response, the worker will be moved immediately. Exception: If the worker is disabled
due to falling or impact, he/she shall not be removed from the confined space unless there is immediate
danger to his/her life. Local fire department rescue personnel shall be notified immediately. The standby
worker may only enter the confined space in case of an emergency (wearing the self contained breathing
apparatus) and only after being relieved by another worker. Safety belt or harness with attached lifeline shall
be used by all workers entering the space with the free end of the line secured outside the entry opening. The
standby worker shall attempt to remove a disabled worker via his lifeline before entering the space.
When practical, these spaces shall be entered through side openings—those within 31⁄2 feet (1.07 m) of
the bottom. When entry must be through a top opening, the safety belt shall be of the harness type that
suspends a person upright and a hoisting device or similar apparatus shall be available for lifting workers out
of the space.
In any situation where their use may endanger the worker, use of a hoisting device or safety belt and
attached lifeline may be discontinued.
When dangerous air contamination is attributable to flammable and/or explosive substances, lighting and
electrical equipment shall be Class 1, Division 1 rated per National Electrical Code and no ignition sources
shall be introduced into the area.
Continuous gas monitoring shall be performed during all confined space operations. If alarm conditions
change adversely, entry personnel shall exit the confined space and a new confined space permit issued.
Rescue. Call the fire department services for rescue. Where immediate hazards to injured personnel are
present, workers at the site shall implement emergency procedures to fit the situation.

Example 2.
Workplace. Meat and poultry rendering plants.
Cookers and dryers are either batch or continuous in their operation. Multiple batch cookers are operated
in parallel. When one unit of a multiple set is shut down for repairs, means are available to isolate that unit
from the others which remain in operation.
Cookers and dryers are horizontal, cylindrical vessels equipped with a center, rotating shaft and agitator
paddles or discs. If the inner shell is jacketed, it is usually heated with steam at pressures up to 150 psig
(1034.25 kPa). The rotating shaft assembly of the continuous cooker or dryer is also steam heated.

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Potential Hazards. The recognized hazards associated with cookers and dryers are the risk that employees
could be:
1. Struck or caught by rotating agitator;
2. Engulfed in raw material or hot, recycled fat;
3. Burned by steam from leaks into the cooker/dryer steam jacket or the condenser duct system if steam
valves are not properly closed and locked out;
4. Burned by contact with hot metal surfaces, such as the agitator shaft assembly, or inner shell of the
cooker/dryer;
5. Heat stress caused by warm atmosphere inside cooker/dryer;
6. Slipping and falling on grease in the cooker/dryer;
7. Electrically shocked by faulty equipment taken into the cooker/dryer;
8. Burned or overcome by fire or products of combustion; or
9. Overcome by fumes generated by welding or cutting done on grease covered surfaces.
Permits. The supervisor in this case is always present at the cooker/dryer or other permit entry confined space
when entry is made. The supervisor must follow the pre-entry isolation procedures described in the entry
permit in preparing for entry, and ensure that the protective clothing, ventilating equipment and any other
equipment required by the permit are at the entry site.
Control of hazards. Mechanical. Lock out main power switch to agitator motor at main power panel. Affix tag to
the lock to inform others that a permit entry confined space entry is in progress.
Engulfment. Close all valves in the raw material blow line. Secure each valve in its closed position using chain
and lock. Attach a tag to the valve and chain warning that a permit entry confined space entry is in progress.
The same procedure shall be used for securing the fat recycle valve.
Burns and heat stress. Close steam supply valves to jacket and secure with chains and tags. Insert solid blank
at flange in cooker vent line to condenser manifold duct system. Vent cooker/dryer by opening access door at
discharge end and top center door to allow natural ventilation throughout the entry. If faster cooling is needed,
use a portable ventilation fan to increase ventilation. Cooling water may be circulated through the jacket to
reduce both outer and inner surface temperatures of cooker/dryers faster. Check air and inner surface
temperatures in cooker/dryer to assure they are within acceptable limits before entering, or use proper
protective clothing.
Fire and fume hazards. Careful site preparation, such as cleaning the area within 4 inches (10.16 cm) of all
welding or torch cutting operations, and proper ventilation are the preferred controls. All welding and cutting
operations shall be done in accordance with the requirements of 29 CFR part 1910, subpart Q, OSHA's
welding standard. Proper ventilation may be achieved by local exhaust ventilation, or the use of portable
ventilation fans, or a combination of the two practices.
Electrical shock. Electrical equipment used in cooker/dryers shall be in serviceable condition.
Slips and falls. Remove residual grease before entering cooker/dryer.
Attendant. The supervisor shall be the attendant for employees entering cooker/dryers.
Permit. The permit shall specify how isolation shall be done and any other preparations needed before making
entry. This is especially important in parallel arrangements of cooker/dryers so that the entire operation need
not be shut down to allow safe entry into one unit.
Rescue. When necessary, the attendant shall call the fire department as previously arranged.

Example 3.
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Workplace. Workplaces where tank cars, trucks, and trailers, dry bulk tanks and trailers, railroad tank cars,
and similar portable tanks are fabricated or serviced.
A. During fabrication. These tanks and dry-bulk carriers are entered repeatedly throughout the fabrication
process. These products are not configured identically, but the manufacturing processes by which they are
made are very similar.
Sources of hazards. In addition to the mechanical hazards arising from the risks that an entrant would be
injured due to contact with components of the tank or the tools being used, there is also the risk that a worker
could be injured by breathing fumes from welding materials or mists or vapors from materials used to coat the
tank interior. In addition, many of these vapors and mists are flammable, so the failure to properly ventilate a
tank could lead to a fire or explosion.
Control of hazards.
Welding. Local exhaust ventilation shall be used to remove welding fumes once the tank or carrier is
completed to the point that workers may enter and exit only through a manhole. (Follow the requirements of
29 CFR 1910, subpart Q, OSHA's welding standard, at all times.) Welding gas tanks may never be brought
into a tank or carrier that is a permit entry confined space.
Application of interior coatings/linings. Atmospheric hazards shall be controlled by forced air ventilation
sufficient to keep the atmospheric concentration of flammable materials below 10% of the lower flammable
limit (LFL) (or lower explosive limit (LEL), whichever term is used locally). The appropriate respirators are
provided and shall be used in addition to providing forced ventilation if the forced ventilation does not maintain
acceptable respiratory conditions.
Permits. Because of the repetitive nature of the entries in these operations, an “Area Entry Permit” will be
issued for a 1 month period to cover those production areas where tanks are fabricated to the point that entry
and exit are made using manholes.
Authorization. Only the area supervisor may authorize an employee to enter a tank within the permit area. The
area supervisor must determine that conditions in the tank trailer, dry bulk trailer or truck, etc. meet permit
requirements before authorizing entry.
Attendant. The area supervisor shall designate an employee to maintain communication by employer
specified means with employees working in tanks to ensure their safety. The attendant may not enter any
permit entry confined space to rescue an entrant or for any other reason, unless authorized by the rescue
procedure and, and even then, only after calling the rescue team and being relieved by as attendant by
another worker.
Communications and observation. Communications between attendant and entrant(s) shall be maintained
throughout entry. Methods of communication that may be specified by the permit include voice, voice powered
radio, tapping or rapping codes on tank walls, signalling tugs on a rope, and the attendant's observation that
work activities such as chipping, grinding, welding, spraying, etc., which require deliberate operator control
continue normally. These activities often generate so much noise that the necessary hearing protection makes
communication by voice difficult.
Rescue procedures. Acceptable rescue procedures include entry by a team of employee-rescuers, use of
public emergency services, and procedures for breaching the tank. The area permit specifies which
procedures are available, but the area supervisor makes the final decision based on circumstances. (Certain
injuries may make it necessary to breach the tank to remove a person rather than risk additional injury by
removal through an existing manhole. However, the supervisor must ensure that no breaching procedure used
for rescue would violate terms of the entry permit. For instance, if the tank must be breached by cutting with a
torch, the tank surfaces to be cut must be free of volatile or combustible coatings within 4 inches (10.16 cm) of
the cutting line and the atmosphere within the tank must be below the LFL.
Retrieval line and harnesses. The retrieval lines and harnesses generally required under this standard are
usually impractical for use in tanks because the internal configuration of the tanks and their interior baffles and
other structures would prevent rescuers from hauling out injured entrants. However, unless the rescue
procedure calls for breaching the tank for rescue, the rescue team shall be trained in the use of retrieval lines
and harnesses for removing injured employees through manholes.
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B. Repair or service of “used” tanks and bulk trailers.
Sources of hazards. In addition to facing the potential hazards encountered in fabrication or manufacturing,
tanks or trailers which have been in service may contain residues of dangerous materials, whether left over
from the transportation of hazardous cargoes or generated by chemical or bacterial action on residues of nonhazardous cargoes.
Control of atmospheric hazards. A “used” tank shall be brought into areas where tank entry is authorized only
after the tank has been emptied, cleansed (without employee entry) of any residues, and purged of any
potential atmospheric hazards.
Welding. In addition to tank cleaning for control of atmospheric hazards, coating and surface materials shall
be removed 4 inches (10.16 cm) or more from any surface area where welding or other torch work will be
done and care taken that the atmosphere within the tank remains well below the LFL. (Follow the
requirements of 29 CFR 1910, subpart Q, OSHA's welding standard, at all times.)
Permits. An entry permit valid for up to 1 year shall be issued prior to authorization of entry into used tank
trailers, dry bulk trailers or trucks. In addition to the pre-entry cleaning requirement, this permit shall require
the employee safeguards specified for new tank fabrication or construction permit areas.
Authorization. Only the area supervisor may authorize an employee to enter a tank trailer, dry bulk trailer or
truck within the permit area. The area supervisor must determine that the entry permit requirements have
been met before authorizing entry.

Appendix D to §1910.146—Sample Permits

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Appendix E to §1910.146—Sewer System Entry
Sewer entry differs in three vital respects from other permit entries; first, there rarely exists any way to
completely isolate the space (a section of a continuous system) to be entered; second, because isolation is
not complete, the atmosphere may suddenly and unpredictably become lethally hazardous (toxic, flammable
or explosive) from causes beyond the control of the entrant or employer, and third, experienced sewer workers
are especially knowledgeable in entry and work in their permit spaces because of their frequent entries. Unlike
other employments where permit space entry is a rare and exceptional event, sewer workers' usual work
environment is a permit space.
(1) Adherence to procedure. The employer should designate as entrants only employees who are
thoroughly trained in the employer's sewer entry procedures and who demonstrate that they follow these entry
procedures exactly as prescribed when performing sewer entries.
(2) Atmospheric monitoring. Entrants should be trained in the use of, and be equipped with, atmospheric
monitoring equipment which sounds an audible alarm, in addition to its visual readout, whenever one of the
following conditions are encountered: Oxygen concentration less than 19.5 percent; flammable gas or vapor at
10 percent or more of the lower flammable limit (LFL); or hydrogen sulfide or carbon monoxide at or above 10
ppm or 35 ppm, respectively, measured as an 8-hour time-weighted average. Atmospheric monitoring
equipment needs to be calibrated according to the manufacturer's instructions. The oxygen sensor/broad
range sensor is best suited for initial use in situations where the actual or potential contaminants have not
been identified, because broad range sensors, unlike substance-specific sensors, enable employers to obtain
an overall reading of the hydrocarbons (flammables) present in the space. However, such sensors only
indicate that a hazardous threshold of a class of chemicals has been exceeded. They do not measure the
levels of contamination of specific substances. Therefore, substance-specific devices, which measure the
actual levels of specific substances, are best suited for use where actual and potential contaminants have
been identified. The measurements obtained with substance-specific devices are of vital importance to the
employer when decisions are made concerning the measures necessary to protect entrants (such as

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employer when decisions are made concerning the measures necessary to protect entrants (such as
ventilation or personal protective equipment) and the setting and attainment of appropriate entry conditions.
However, the sewer environment may suddenly and unpredictably change, and the substance-specific
devices may not detect the potentially lethal atmospheric hazards which may enter the sewer environment.
Although OSHA considers the information and guidance provided above to be appropriate and useful in
most sewer entry situations, the Agency emphasizes that each employer must consider the unique
circumstances, including the predictability of the atmosphere, of the sewer permit spaces in the employer's
workplace in preparing for entry. Only the employer can decide, based upon his or her knowledge of, and
experience with permit spaces in sewer systems, what the best type of testing instrument may be for any
specific entry operation.
The selected testing instrument should be carried and used by the entrant in sewer line work to monitor
the atmosphere in the entrant's environment, and in advance of the entrant's direction of movement, to warn
the entrant of any deterioration in atmospheric conditions. Where several entrants are working together in the
same immediate location, one instrument, used by the lead entrant, is acceptable.
(3) Surge flow and flooding. Sewer crews should develop and maintain liaison, to the extent possible, with
the local weather bureau and fire and emergency services in their area so that sewer work may be delayed or
interrupted and entrants withdrawn whenever sewer lines might be suddenly flooded by rain or fire
suppression activities, or whenever flammable or other hazardous materials are released into sewers during
emergencies by industrial or transportation accidents.
(4) Special Equipment. Entry into large bore sewers may require the use of special equipment. Such
equipment might include such items as atmosphere monitoring devices with automatic audible alarms, escape
self-contained breathing apparatus (ESCBA) with at least 10 minute air supply (or other NIOSH approved selfrescuer), and waterproof flashlights, and may also include boats and rafts, radios and rope stand-offs for
pulling around bends and corners as needed.

Appendix F to §1910.146—Rescue Team or Rescue Service Evaluation Criteria (NonMandatory)
(1) This appendix provides guidance to employers in choosing an appropriate rescue service. It contains
criteria that may be used to evaluate the capabilities both of prospective and current rescue teams. Before a
rescue team can be trained or chosen, however, a satisfactory permit program, including an analysis of all
permit-required confined spaces to identify all potential hazards in those spaces, must be completed. OSHA
believes that compliance with all the provisions of §1910.146 will enable employers to conduct permit space
operations without recourse to rescue services in nearly all cases. However, experience indicates that
circumstances will arise where entrants will need to be rescued from permit spaces. It is therefore important
for employers to select rescue services or teams, either on-site or off-site, that are equipped and capable of
minimizing harm to both entrants and rescuers if the need arises.
(2) For all rescue teams or services, the employer's evaluation should consist of two components: an
initial evaluation, in which employers decide whether a potential rescue service or team is adequately trained
and equipped to perform permit space rescues of the kind needed at the facility and whether such rescuers
can respond in a timely manner, and a performance evaluation, in which employers measure the performance
of the team or service during an actual or practice rescue. For example, based on the initial evaluation, an
employer may determine that maintaining an on-site rescue team will be more expensive than obtaining the
services of an off-site team, without being significantly more effective, and decide to hire a rescue service.
During a performance evaluation, the employer could decide, after observing the rescue service perform a
practice rescue, that the service's training or preparedness was not adequate to effect a timely or effective
rescue at his or her facility and decide to select another rescue service, or to form an internal rescue team.

A. Initial Evaluation
I. The employer should meet with the prospective rescue service to facilitate the evaluations required by
§1910.146(k)(1)(i) and §1910.146(k)(1)(ii). At a minimum, if an off-site rescue service is being considered, the
employer must contact the service to plan and coordinate the evaluations required by the standard. Merely
posting the service's number or planning to rely on the 911 emergency phone number to obtain these services
at the time of a permit space emergency would not comply with paragraph (k)(1) of the standard.
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II. The capabilities required of a rescue service vary with the type of permit spaces from which rescue
may be necessary and the hazards likely to be encountered in those spaces. Answering the questions below
will assist employers in determining whether the rescue service is capable of performing rescues in the permit
spaces present at the employer's workplace.
1. What are the needs of the employer with regard to response time (time for the rescue service to
receive notification, arrive at the scene, and set up and be ready for entry)? For example, if entry is to be
made into an IDLH atmosphere, or into a space that can quickly develop an IDLH atmosphere (if ventilation
fails or for other reasons), the rescue team or service would need to be standing by at the permit space. On
the other hand, if the danger to entrants is restricted to mechanical hazards that would cause injuries (e.g.,
broken bones, abrasions) a response time of 10 or 15 minutes might be adequate.
2. How quickly can the rescue team or service get from its location to the permit spaces from which
rescue may be necessary? Relevant factors to consider would include: the location of the rescue team or
service relative to the employer's workplace, the quality of roads and highways to be traveled, potential
bottlenecks or traffic congestion that might be encountered in transit, the reliability of the rescuer's vehicles,
and the training and skill of its drivers.
3. What is the availability of the rescue service? Is it unavailable at certain times of the day or in certain
situations? What is the likelihood that key personnel of the rescue service might be unavailable at times? If the
rescue service becomes unavailable while an entry is underway, does it have the capability of notifying the
employer so that the employer can instruct the attendant to abort the entry immediately?
4. Does the rescue service meet all the requirements of paragraph (k)(2) of the standard? If not, has it
developed a plan that will enable it to meet those requirements in the future? If so, how soon can the plan be
implemented?
5. For off-site services, is the service willing to perform rescues at the employer's workplace? (An
employer may not rely on a rescuer who declines, for whatever reason, to provide rescue services.)
6. Is an adequate method for communications between the attendant, employer and prospective rescuer
available so that a rescue request can be transmitted to the rescuer without delay? How soon after notification
can a prospective rescuer dispatch a rescue team to the entry site?
7. For rescues into spaces that may pose significant atmospheric hazards and from which rescue entry,
patient packaging and retrieval cannot be safely accomplished in a relatively short time (15-20 minutes),
employers should consider using airline respirators (with escape bottles) for the rescuers and to supply rescue
air to the patient. If the employer decides to use SCBA, does the prospective rescue service have an ample
supply of replacement cylinders and procedures for rescuers to enter and exit (or be retrieved) well within the
SCBA's air supply limits?
8. If the space has a vertical entry over 5 feet in depth, can the prospective rescue service properly
perform entry rescues? Does the service have the technical knowledge and equipment to perform rope work
or elevated rescue, if needed?
9. Does the rescue service have the necessary skills in medical evaluation, patient packaging and
emergency response?
10. Does the rescue service have the necessary equipment to perform rescues, or must the equipment
be provided by the employer or another source?

B. Performance Evaluation
Rescue services are required by paragraph (k)(2)(iv) of the standard to practice rescues at least once
every 12 months, provided that the team or service has not successfully performed a permit space rescue
within that time. As part of each practice session, the service should perform a critique of the practice rescue,
or have another qualified party perform the critique, so that deficiencies in procedures, equipment, training, or
number of personnel can be identified and corrected. The results of the critique, and the corrections made to
respond to the deficiencies identified, should be given to the employer to enable it to determine whether the
rescue service can quickly be upgraded to meet the employer's rescue needs or whether another service must
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be selected. The following questions will assist employers and rescue teams and services evaluate their
performance.
1. Have all members of the service been trained as permit space entrants, at a minimum, including
training in the potential hazards of all permit spaces, or of representative permit spaces, from which rescue
may be needed? Can team members recognize the signs, symptoms, and consequences of exposure to any
hazardous atmospheres that may be present in those permit spaces?
2. Is every team member provided with, and properly trained in, the use and need for PPE, such as SCBA
or fall arrest equipment, which may be required to perform permit space rescues in the facility? Is every team
member properly trained to perform his or her functions and make rescues, and to use any rescue equipment,
such as ropes and backboards, that may be needed in a rescue attempt?
3. Are team members trained in the first aid and medical skills needed to treat victims overcome or injured
by the types of hazards that may be encountered in the permit spaces at the facility?
4. Do all team members perform their functions safely and efficiently? Do rescue service personnel focus
on their own safety before considering the safety of the victim?
5. If necessary, can the rescue service properly test the atmosphere to determine if it is IDLH?
6. Can the rescue personnel identify information pertinent to the rescue from entry permits, hot work
permits, and MSDSs?
7. Has the rescue service been informed of any hazards to personnel that may arise from outside the
space, such as those that may be caused by future work near the space?
8. If necessary, can the rescue service properly package and retrieve victims from a permit space that
has a limited size opening (less than 24 inches (60.9 cm) in diameter), limited internal space, or internal
obstacles or hazards?
9. If necessary, can the rescue service safely perform an elevated (high angle) rescue?
10. Does the rescue service have a plan for each of the kinds of permit space rescue operations at the
facility? Is the plan adequate for all types of rescue operations that may be needed at the facility? Teams may
practice in representative spaces, or in spaces that are “worst-case” or most restrictive with respect to internal
configuration, elevation, and portal size. The following characteristics of a practice space should be
considered when deciding whether a space is truly representative of an actual permit space:
(1) Internal configuration.
(a) Open—there are no obstacles, barriers, or obstructions within the space. One example is a water
tank.
(b) Obstructed—the permit space contains some type of obstruction that a rescuer would need to
maneuver around. An example would be a baffle or mixing blade. Large equipment, such as a ladder or
scaffold, brought into a space for work purposes would be considered an obstruction if the positioning or size
of the equipment would make rescue more difficult.
(2) Elevation.
(a) Elevated—a permit space where the entrance portal or opening is above grade by 4 feet or more. This
type of space usually requires knowledge of high angle rescue procedures because of the difficulty in
packaging and transporting a patient to the ground from the portal.
(b) Non-elevated—a permit space with the entrance portal located less than 4 feet above grade. This type
of space will allow the rescue team to transport an injured employee normally.
(3) Portal size.
(a) Restricted—A portal of 24 inches or less in the least dimension. Portals of this size are too small to
allow a rescuer to simply enter the space while using SCBA. The portal size is also too small to allow normal
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spinal immobilization of an injured employee.
(b) Unrestricted—A portal of greater than 24 inches in the least dimension. These portals allow relatively
free movement into and out of the permit space.
(4) Space access.
(a) Horizontal—The portal is located on the side of the permit space. Use of retrieval lines could be
difficult.
(b) Vertical—The portal is located on the top of the permit space, so that rescuers must climb down, or
the bottom of the permit space, so that rescuers must climb up to enter the space. Vertical portals may require
knowledge of rope techniques, or special patient packaging to safely retrieve a downed entrant.

[58 FR 4549, Jan. 14, 1993; 58 FR 34845, 34846, June 29, 1993, as amended at 59 FR 26114, May
19, 1994; 63 FR 66038, 66039, Dec. 1, 1998; 76 FR 80739, Dec. 27, 2011]
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