Permit-required confined spaces: Knowing the issues could save a life, or two
July 1, 2006
Not too long ago, I helped investigate a â€œdouble fatalityâ€ that occurred in California. The first victim was the initial entrant into a permit-required confined space. The second victim was a well-meaning fellow employee attempting a rescue effort. Very sadly, this type of tragedy is not uncommon. As I stood directly below the pit, peering inside, I wondered when this needless horror is going to stop.
OSHA defines itOSHA covers permit-required confined spaces (PRCS) in 29 CFR 1910.146. The agency defines a confined space as having a limited or restricted means of entry or exit, being large enough for an employee to enter fully and perform assigned work, and not designed for continuous occupancy by the employee. OSHA refers to underground vaults, tanks, storage bins, pits and diked areas, vessels (some furnaces) and silos.
The â€œconfined spaceâ€ definition must be satisfied for 1910.146 to apply. Yet, some â€œconfined spacesâ€ are not covered by the standard. To be permit-required (and thus covered by the standard), the above definition must be met. Further, the space must have at least one of the following characteristics:
- contains or has the potential to contain a hazardous atmosphere;
- contains a material with the potential to engulf someone who enters the space;
- has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section;
- contains any other recognized serious safety or health hazards.
Letâ€™s examine some specific issues involving PRCS.
â€œOtherâ€ safety hazards â€” The fourth category listed above is somewhat vague. Lockout/tagout is the most common category example that would fit this category. The lack of adequate lockout/tagout implementation has been considered by OSHA to place a confined space into a permit-required confined space category, even if there is no realistic danger of oxygen deficiency, vapor ignition or being buried by material. Similar concerns could involve the lack of electrical safety-related work practices performed in a confined space. The potential for drowning in water or another liquid (rather than engulfment in grain, sand or flour, as natural examples) may fit into the last category as well.
â€œHazardous atmospheresâ€ â€” This can relate to toxic exposure conditions that pose an immediate or delayed threat to life, would cause irreversible adverse health effects, would interfere with an individualâ€™s ability to escape unaided from a permit space, or where injury, acute illness, or incapacitation are in the offing. 1910.146 specifies (at times by reference) how lower flammable limits (LFL), as well as dose and permissible exposure limits (PEL) figure into the criteria.
Hazardous atmospheres also include where explosions can result, depending upon concentration and type of vapor, gas, mist or dust. Then there is the critical oxygen-deficient atmosphere (less than 19.5% by volume), and the very rare oxygen-enriched atmosphere (more than 23.5%). Be concerned if entrants appear to be uncommonly giddy. All potentially exposed entrants must understand that carbon monoxide is odorless, colorless, tasteless and deadly.
â€œInternal configurationâ€ â€” This category can be encountered with funnel-type construction, which can result in a leg becoming stuck and/or cause great difficulty (by poor footing) for a person attempting to evacuate the space. Combining that configuration with an engulfment hazard can significantly add to the risk. Note that a person can be killed by engulfment even if the head is not buried; the chest can be thwarted from expanding.
What constitutes entry? â€” Employers are required to identify and evaluate permit space hazards before allowing entry. Entry occurs when any part of a personâ€™s body breaks the plane of an opening into the space. Although this can include, for example, an arm, professional judgment often dictates that OSHA not cite when that is the only bodily entry into the space. What if just a face intrudes into an entry port? Would it be illogical to cite? In many cases, it would make perfect sense to cite, because a person, even standing while that entry is made, could be overcome and perhaps come to rest with the head falling into a deadly atmosphere.
Postings â€” If a PRCS is identified, exposed employees must be informed of the location and danger. Unambiguous postings should be provided. If employees are to enter, a written permit space program must be developed and made available.
Safe practices â€” Safe practices must be established. This includes isolation, purging, inerting, ventilation and barricades. Conditions in the space must be tested before entry operations, and monitored during entry. Initial testing can often be performed by lowering an instrument into the space, with the instrument operator/reader out of harmâ€™s way. In some cases, the necessary data can be gathered from instruments permanently set-up in the space, while â€œthe numbersâ€ can be read remotely. In other cases (generally less desirable), an instrument may be brought into the space by a worker wearing a self-contained breathing apparatus.
Instrument calibration â€” Proper calibration of testing instruments is critical and must never be assumed. The testing (to be documented) sequence is: oxygen, atmospheric combustibles, then toxic air contaminants.
Proper authorization â€” The employer must implement measures to prevent unauthorized entry. There must be a written system for preparing, issuing, using and canceling permits. The permit is for particular spaces at particular times, with detailed requirements for that space.
Permit items â€” Some other key permit items to be listed are authorized entrants, attendants, entry supervisors (printed name and signature), hazard control measures, communications procedures and equipment, and necessary personal protective and rescue equipment. As in the California incident, rescuers (inadequately trained and/or acting on reflex) often perish along with those they attempt to save. Never assume what their knowledge, skill or attitude may be. Teach the â€œwhysâ€ and â€œhows.â€ Please dismiss any notion that your rescue plan can be to call an off-site professional (even if he/she has been contracted for such purpose) at the time of an emergency.
The standard saysâ€¦The standard contains detailed, separate sections on training, authorized entrant duties, attendant duties, entry supervisor duties, and rescue and emergency services. As a host employer, be sure to inform contractor employees of PRCS hazards to which they may be exposed.
Further, one part of the standard addresses alternate procedures for when the employer can demonstrate that the only hazard posed by the permit space is an actual or potential hazardous atmosphere. The first (of many) requirements is that the employer substantiate that continuous forced air ventilation, alone, is sufficient to maintain that permit space safe for entry.
Sidebar 1: Appendices to the standardThere are a number of very helpful non-mandatory appendices to the 1910.146 standard on permit-required confined spaces.
The appendices cover:
- PRCS decision flow chart;
- recommended procedures for atmospheric testing;
- examples of acceptable permit space entry programs;
- samples of acceptable permits; and
- recommended procedures for sewer entry.
Sidebar 2: Itâ€™s a dirty job, butâ€¦Sewer entry differs in three vital respects from other permit entries. First, there rarely exists any way to completely isolate the space â€” which is a section of a continuous system â€” 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 workersâ€™ usual work environment is a permit space.
In addition to adhering to procedures and conducting atmospheric monitoring, sewer crews should develop and maintain liaison with the local weather bureau and fire and emergency services in their area. This will enable sewer work to 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.
Source: OSHA, 1910.146 Appendix E