Subpart AA
Under 1926.1202, a "confined space" is a space that an employee can bodily enter, has limited or restricted means for entry or exit, and is not designed for continuous employee occupancy.
A space is a "permit-required confined space" under 1926.1202 if it is a confined space and it (1) contains or can contain a hazardous atmosphere, (2) contains material that could engulf an entrant, (3) has an internal configuration that could trap or asphyxiate an entrant (inwardly converging walls or tapering floor), or (4) contains any other recognized serious safety or health hazard.
"Acceptable entry conditions" are the conditions that must exist in a permit space before an employee may enter so employees can enter and work safely.
An "authorized entrant" is an employee who the entry supervisor has authorized to enter a permit space.
An "entry supervisor" is the qualified person (for example, employer, foreman, or crew chief) responsible for determining if acceptable entry conditions are present, authorizing entry, overseeing entry operations, and terminating entry when required.
An "entry employer" is any employer who decides that its employee will enter a permit space; a "host employer" owns or manages the property where the work is taking place; the "controlling contractor" is the employer with overall responsibility for construction at the worksite.
"Isolate" or "isolation" means protecting employees in a confined space from the release of energy or material and from contact with physical hazards by means such as blanking/blinding, misaligning or removing sections of lines, double block and bleed, lockout/tagout, blocking mechanical linkages, or placing barriers.
"Blanking or blinding" means absolutely closing a pipe, line, or duct with a solid plate that completely covers the bore and can withstand maximum pressure with no leakage; "double block and bleed" means closing and locking or tagging two in-line valves and opening and locking or tagging a drain or vent between them.
No—under 1926.1202, "control" means engineering actions (for example, ventilation) used to reduce and maintain hazard levels inside a confined space, and the standard explicitly states that personal protective equipment is not a control.
IDLH is any condition that would interfere with an individual's ability to escape unaided from a permit space and that poses a threat to life or would cause irreversible adverse health effects.
"Engulfment" means surrounding and effectively capturing a person by a liquid or finely divided flowable solid that can be aspirated and cause death or can exert enough force to cause strangulation, constriction, crushing, or suffocation.
"Inerting" is displacing the atmosphere in a permit space by a noncombustible gas (for example, nitrogen) so the atmosphere is noncombustible; inerting can produce an IDLH oxygen-deficient atmosphere because it reduces oxygen levels below safe limits.
The "lower flammable limit (LFL)" is the minimum concentration of a substance in air needed for an ignition source to cause a flame or explosion; a flammable atmosphere is hazardous when flammable gas, vapor, or mist exceeds 10 percent of its LFL.
A "hazardous atmosphere" is one that may expose employees to death, incapacitation, impaired self-rescue, injury, or acute illness from any of: (1) flammable gas/vapor/mist over 10% of LFL; (2) airborne combustible dust at a concentration approximated by obscured vision at 5 feet or less; (3) oxygen below 19.5% or above 23.5%; (4) atmospheric concentration of any substance above its dose or PEL; or (5) any other atmospheric condition that is immediately dangerous to life or health.
A "prohibited condition" is any condition in a permit space that is not allowed by the entry permit during the period when entry is authorized; for example, a hazardous atmosphere that the permit does not allow is a prohibited condition.
A "representative permit space" is a mock-up of a confined space that closely matches the entrance openings, size, configuration, and accessibility of the actual permit space and is used for training and familiarizing authorized entrants with entry procedures.
A "retrieval system" is equipment (including a retrieval line, appropriate harness or wristlets/anklets, and a lifting device or anchor) used for non-entry rescue of persons from permit spaces; employers must provide retrieval systems unless they would increase risk or are infeasible, in which case alternative rescue measures are required.
"Testing" is the process used to identify and evaluate hazards that may confront entrants in a permit space and must be performed to devise control measures and to determine if acceptable entry conditions are present immediately prior to and during entry.
An "entry" occurs as soon as any part of an entrant's body breaks the plane of an opening into a space, and entry includes all ensuing work activities inside that space.
"Testing" is the initial process to identify and evaluate hazards in a permit space before entry, while "monitoring" is the ongoing process of checking for changes in hazards after entry and may be periodic or continuous.
Examples of "limited or restricted means for entry or exit" include trip hazards, poor illumination, slippery floors, inclining surfaces, and ladders—conditions that could impede movement into or out of a confined space.
A "physical hazard" is an existing or potential hazard that can cause death or serious physical damage; examples include explosives, mechanical/electrical/hydraulic/pneumatic energy, radiation, temperature extremes, engulfment, noise, and inwardly converging surfaces. Chemicals that cause death or serious physical damage through skin or eye contact (rather than inhalation) are considered physical hazards.
A hazardous atmosphere is a "prohibited condition" in a permit space unless the employer can demonstrate that personal protective equipment will provide effective protection for each employee and the employer provides appropriate PPE.
An "oxygen-deficient atmosphere" is one that contains less than 19.5 percent oxygen by volume; an "oxygen-enriched atmosphere" contains more than 23.5 percent oxygen by volume.
"Entry rescue" occurs when a rescue service enters a permit space to rescue employees, while "non-entry rescue" is when a rescue service (often the attendant) retrieves employees without entering the permit space using retrieval systems or other methods.
"Line breaking" means intentionally opening 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; it is important because line breaking can introduce hazardous atmospheres or physical hazards into a confined space that require isolation and testing before entry.
A "qualified person" is someone who by degree, certificate, professional standing, or by extensive knowledge, training, and experience has demonstrated the ability to solve problems related to the subject matter; this qualification is required for roles like the entry supervisor or others who must make technical determinations under the permit-space program.
"Test or testing" means performing specified tests to identify and evaluate hazards so employers can implement adequate controls and verify that acceptable entry conditions exist right before and while employees are in the permit space.
Under 1926.1202, a "hazard" is either a physical hazard or a hazardous atmosphere; a "hazardous atmosphere" refers to dangerous air conditions (flammability, oxygen, toxicants, etc.), while a "physical hazard" refers to non-atmospheric dangers like mechanical energy, engulfment, radiation, or temperature extremes.