Confined Space Safety: What You Need to Know

A lot of things can go wrong when working in tight spaces, and not just bumping your head on a low ceiling or getting claustrophobic. Each year, there are dozens of U.S. worker fatalities related to confined spaces, which expose workers to dangers such as hazardous atmospheres, fires, explosions, and engulfment. While these numbers may be low compared to other hazard categories, many of these deaths are avoidable.

OSHA enforces laws to protect employees who work in confined spaces, but incidents still happen due to inadequate training and improper procedures. Keep reading to find out everything you need to know about working in confined spaces.

What Is a Confined Space?

Many workplaces contain areas that are considered “confined spaces” but what does that actually mean? To qualify as a confined space, an area must meet three requirements. It must:

• Be large enough for an employee to enter and perform assigned work in
• Not be designed for continuous occupancy
• Have limited or restricted means of entry or exit

Common confined spaces include vaults, tanks, storage bins, manholes, pits, diked areas, vessels, silos, hoppers, equipment housing, pipelines, and other similar areas.

There are two different types of confined spaces in the workplace: non-permit confined spaces and permit-required confined spaces. Non-permit confined spaces are spaces that don’t contain or have the potential to contain any hazards capable of causing death or serious physical harm.

Permit-required confined spaces pose a more serious risk to workers’ health. To qualify as a permit-required space, a confined space must meet at least one of the following criteria:

• Contains or has the potential to contain a hazardous atmosphere
• Contains a material that could engulf someone who enters the space
• Has an internal configuration that could cause a worker to become trapped or asphyxiated
• Contains any other recognized serious safety or health hazards

For the purposes of this article, any reference to “confined spaces” will be referring to permit-required confined spaces.

What Hazards Are Associated with Confined Spaces?

Although there are numerous hazards that come with working in confined spaces, they can be divided into four broad categories. Learn about some of the most common hazards found within each category below.

Atmospheric

Hazardous atmospheres are the biggest dangers that workers face in confined spaces. A hazardous atmosphere is any atmosphere that may expose workers to the risk of death, injury, acute illness, or incapacitation, or reduce their ability to escape unaided from a confined space. Hazardous atmospheres can be caused by flammable or combustible materials in the air, too much or too little oxygen in the air, or chemical substances in the air.

Particularly dangerous atmospheres are classified as immediately dangerous to life or health, or IDLH, atmospheres. To be classified as an IDLH atmosphere, the atmosphere must contain a condition that poses an immediate or delayed threat to life, be likely to cause irreversible adverse health effects, or interfere with an individual’s ability to escape unaided from a confined space.

Employees who work in IDLH atmospheres must receive special safety training and use IDLH-specific equipment and procedures to prevent death and serious injury or illness. If employees must work in an IDLH atmosphere, there must be a rescuer on standby outside the confined space.

Physical

Confined spaces that contain liquids or flowable solids like grain, corn, or coal pose an engulfment hazard. Engulfment occurs when a person is pulled under the surface of a liquid or flowable solid, and can result in death from strangulation, constriction, or crushing. Engulfment is particularly common in agricultural facilities that store large quantities of grain, spices, and other foods in silos and other confined spaces.

Small entrances can make it difficult for rescuers with oxygen tanks to enter. Limited ventilation can allow gases, vapors, and fumes to build up, creating hazardous atmospheres that wouldn’t form in an adequately ventilated, open space. Even household cleaning products can give off deadly fumes in a confined space. Electrical equipment can cause electric shock or pull workers into machinery if it is not properly shut down before entry.

Configuration

When the design, shape, or dimension of a confined space poses a risk to occupants, that space is said to possess a configuration hazard. The main concern when working within a configuration hazard confined space is that getting into, moving around within, or getting out of such a confined space can be difficult, hazardous, awkward, or abnormally time-consuming.

Further, should an incident occur, configuration hazards may complicate or prevent a simple self-rescue or non-entry rescue, meaning the only option is to send your rescue team into the confined space to initiate a rescue.

Biological

Biological hazards are most associated with confined spaces such as sewer systems, silos, and culverts, but workers should never overlook the possibility of these hazards existing in other types of confined spaces.

Common biological hazards include rodent droppings, poisonous plants, sewage, wild animals, sharp objects, stagnant water, and various molds or fungi.

Remember that a confined space is not limited to the hazards of just one category. After conducting a hazard assessment, you may find that a particular confined space possesses hazards from two or more categories. When all potential hazards are identified, only then can safe training and safe work be completed.

What Steps Must Be Taken to Prepare for a Confined Space Entry?

If your jobsite includes a permit-required confined space, you must create an entry permit, which is a written document posted by all entrances to a confined space. The entry permit must be signed by the supervisor who authorizes entry.

The entry permit must include:

• Identification of the space
• Purpose, dates, and duration of the permitted entry
• Names of authorized entrants and the current attendant and supervisor
• Hazards of the permit space and their controls, including atmospheric testing results
• Acceptable entry conditions
• Rescue services
• Communication procedures
• Equipment provided, such as PPE and rescue equipment
• Any additional necessary information, including any additional permits that will be needed (such as hot work permits)

As part of the development of the permit, a properly trained and qualified individual must perform atmospheric testing in the confined space. This individual must also sign the entry permit.

Tests should be performed to determine the:

• Oxygen content
  • The atmosphere can be oxygen deficient (concentration is less than 19.5%) or oxygen enriched (concentration is greater than 23.5%).
  • Both atmospheres can put entry workers at risk. An oxygen deficient atmosphere can lead to loss of consciousness and suffocation. An oxygen enriched atmosphere can lead to a higher risk of flammability, as well as spontaneous fires and explosions.
• Presence of flammable gases and vapors
  • Every flammable gas or vapor has a lower flammable limit, or LFL
    • LFL is the lowest concentration of a combustible material in air that can ignite
  • The concentration of combustible material in the air must be less than 10 percent of the LFL.
• Presence of potential toxic air contaminants

Once the tests are completed, all results must be logged on the entry permit. The confined space entry supervisor must verify that these tests were conducted and documented properly by a qualified person. In addition, the entry supervisor must ensure the air is monitored when workers are in the space if there is any risk of a hazardous atmosphere developing.

Before any work in a confined space begins, you must take precautions to ensure worker safety. Your facility must correct all known hazards and create a system for identifying new hazards. Before work can begin, all employees entering the confined space must be trained.

Additional training must be provided when job duties change, if the permit space presents any new hazard, or if a worker shows signs of not understanding safety procedures. Training records must be kept for inspection by employees or their authorized representatives if requested.

Supervisor Responsibilities

The responsibilities of a confined space entry supervisor begin before any trained employees enter the confined space. They must understand all hazards in the space, including the mode, signs, symptoms, and consequences of exposure to each, and be familiar with the required hazard controls. They must be able to read an entry permit and verify that entry conditions are acceptable before entry is allowed.

The entry supervisor must also understand:

• Communication plans between the entrant and attendant
• Rescue plans and services
• How to oversee the confined space entry operations and routinely verify ongoing conditions

Confined space entry supervisors also have the final word in determining acceptable conditions for employees working in the space. They are responsible for terminating entry procedures whenever necessary for the safety of employees. Employees should never enter a confined space without a properly qualified supervisor present.

Entry supervisors also have the power to cancel a permit and terminate entry at any time. If unacceptable conditions arise, or when the work is completed, the permit is canceled. If additional entry is required, a new permit must be made.

While creating a new entry permit can seem extensive and repetitive, changes to a confined space’s atmosphere can occur at any time and for many reasons, so new permits are required each time. Entry supervisors should never allow entry to anyone not on the permit, or when the permit has been canceled, as it could lead to serious health effects and even death.

Let Us Help You Get Prepared

Dangerous conditions can be heightened in confined spaces due to their atmospheric conditions and limited means of escape. Small entrances, lack of adequate ventilation, and hazardous atmospheres can pose serious and potentially fatal risks to workers.

To lessen the likelihood of injury and death in confined spaces, your facility should properly follow all confined space permit regulations and train workers on safe confined space entry procedures. HSI offers multiple training courses covering confined space hazards, personnel responsibilities, emergency procedures, and more.

Looking for online training on confined spaces and more? Click here to see what HSI has to offer!