What is a Confined Space? Guide to Confined Space Safety and Regulations

what is a confined space

How is a Confined Space Defined?

The Occupational Safety and Health Administration (OSHA) defines a confined space as an area with limited or restricted means for entry or exit and is generally not designed for continuous human occupancy. Confined work spaces are large enough for a worker or workers to enter and perform tasks, but have limited openings for entry and exit. This particular characteristic is what primarily influences and affects confined space safety as it complicates first aid, rescue, evacuation, and other emergency response procedures.

A confined space typically exhibits several defining characteristics:

  • Limited Openings for Entry and Exit: These openings are often narrow or restrict movement, making it challenging for equipment and workers to move freely.
  • Unsuitable for Continuous Worker Occupancy: Due to factors like poor ventilation, confined spaces are not safe for workers to stay in for extended periods.
  • Designed for Other Purposes: These spaces are primarily intended for storage, processing, or housing equipment. They include tanks, vessels, silos, storage bins, hoppers, vaults, pits, manholes, tunnels, equipment housings, ductwork, and pipelines.
  • Variable Size and Shape: The dimensions of confined spaces can vary widely, which can affect the risk level and the safety measures needed.
  • Isolation: Many confined spaces are isolated from regular work areas, which can delay emergency response times and communication with supervisors or emergency teams.

Types of Hazards in Confined Spaces

Working in confined spaces exposes individuals to various types of hazards that can jeopardize their safety. It is crucial to identify and understand these hazards to implement appropriate control measures. The following are some common types of hazards found in confined spaces:

Atmospheric Hazards: Confined spaces can have an atmosphere that is deficient in oxygen or contains toxic gases, vapors, or dust. These atmospheric hazards can lead to asphyxiation, respiratory problems, or chemical exposures.

Engulfment Hazards: Some confined spaces, such as grain silos or tanks, pose a risk of engulfment. Workers can be buried or trapped by materials such as grain, sand, or water, resulting in suffocation or crushing injuries.

Physical Hazards: Physical hazards in confined spaces include restricted spaces, sharp edges, protruding objects, or moving machinery. These hazards can cause injuries such as cuts, bruises, or fractures.

Temperature Extremes: Confined spaces may have extreme temperatures, either excessively hot or cold. Exposure to extreme temperatures can lead to heat exhaustion, heatstroke, frostbite, or hypothermia.

Noise and Vibrations: Some confined spaces may have high noise levels or vibrations from machinery or equipment. Prolonged exposure to these factors can result in hearing loss or other health issues.

 

4 Types of Confined Spaces

worker entering a confined space


Confined spaces can be classified into 4 categories based on their characteristics and the level of risk they present. Understanding these classifications helps in determining the appropriate safety measures for each type of confined space. The 4 classifications are as follows:

Non-permit Required Confined Space

A non-permit required confined space refers to work areas 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. These spaces do not require a permit for entry because they pose no significant risk under normal conditions. However, they still require a basic level of hazard assessment and emergency procedures.

Permit Required Confined Space

A permit-required confined space is an environment the OSHA has specifically defined to ensure the close monitoring of hazardous work environments. According to OSHA, a permit-required confined space has one or more of the following characteristics:

  • Contains or has the potential to contain a hazardous atmosphere.
  • Contains a material that has the potential for engulfing an entrant.
  • 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 cross-section.
  • Contains any other recognized serious safety or health hazard.

Entering this particular confined space requires a permit that specifies the work to be done, the personnel involved, and the safety measures to be implemented. This permit acts as a control measure to ensure that all potential hazards are evaluated and mitigated before entry.

Alternate Procedure Confined Space

Alternate procedure confined spaces meet the requirements for a permit-required space but have sufficient safeguards in place to allow for a less stringent entry procedure. For instance, if a confined space has potential atmospheric hazards that can be completely mitigated by continuous forced air ventilation, the space might be reclassified to an alternate procedure space. In this scenario, continuous monitoring and immediate emergency response are crucial, but the full permit system might not be necessary if the only hazard has been fully controlled.

Restricted Space

Restricted space is a term used less formally in the industry and may not always be recognized in all safety regulations. It generally refers to spaces that pose significant physical entry or movement challenges but do not necessarily contain the hazardous atmospheres or other serious hazards typical of permit-required confined spaces. Access to these spaces may be physically restricted due to size or access points, requiring specialized training and equipment for safe entry and exit.

 

Confined Space Safety Regulations and Standards

Safely navigating confined spaces can be complex and challenging. It requires a deep and thorough understanding of specific safety requirements, standards, and regulations designed to protect workers. These regulations are meticulously crafted to address the various risks associated with confined spaces and ensure safe working conditions.

Requirements for Confined Space Entry

Ensuring safe entry into confined spaces involves meticulous preparation and adherence to established safety protocols. Before any confined space entry, stringent preparation and risk assessment must be followed. These include:

  • Identification of Confined Spaces: Clearly identifying and marking all confined spaces through clear and visible workplace signs on a worksite ensures that all personnel are aware of potential hazards.
  • Risk Assessment: Conducting a comprehensive hazard assessment to identify and evaluate potential risks within the confined space. This assessment must consider all possible hazards, from atmospheric to physical dangers.
  • Development of Entry Procedures: Establishing safe entry procedures, including securing the space from unauthorized access and ensuring proper use of safety equipment.
  • Emergency Preparedness: Formulating and practicing emergency and rescue procedures tailored to the specific characteristics and hazards of the confined space.
  • Training: Providing specialized training for all personnel involved in confined space operations to ensure they understand the risks, equipment, and procedures necessary for safe entry and work.

Confined Space Permit To Work System

In relation to confined space entry procedures and preparations, a confined space permit to work is a formal document used specifically to control ingress into restricted hazardous areas and ensure that all safety measures are in place before and during entry. This system is a fundamental part of the safety protocols in particular permit space designed to protect workers from the inherent risks of confined spaces.

Purpose of Entry
The permit begins by clearly stating the specific purpose of the entry. This includes a detailed description of the work to be performed within the confined space, such as maintenance, inspection, cleaning, or repair activities. Clearly defining the purpose helps in identifying the associated risks and necessary precautions.

Duration of Permit
The permit specifies the time frame during which the entry is authorized. This is often limited to one shift to ensure that conditions within the confined space are reassessed regularly. The duration includes the start and end times, ensuring that the permit does not extend beyond the period when safety measures have been evaluated and deemed adequate.

List of Entrants
A confined space permit to work must include a list of all personnel authorized to enter the confined space. This ensures that only trained and qualified individuals are allowed entry. This section should include the names of all workers who will enter the confined space, as well as the names of the attendants who will remain outside the space to monitor the entry and provide assistance in case of an emergency and the supervisors responsible for overseeing permit space entry operations.

Safety Measures
The permit outlines all necessary safety measures to be implemented before and during the confined space entry. These measures are based on the risk assessment and include the following:

  • Isolation of Hazards: Steps to isolate or control all hazardous energy sources, such as lockout tagout procedures on electrical systems or shutting down machinery.
  • Ventilation: Procedures for ensuring adequate ventilation within the confined space to maintain safe atmospheric conditions.
  • Atmospheric Testing: Requirements for pre-entry and continuous monitoring of the air quality within the confined space to determine oxygen levels, lower explosive limit (LEL), and hazardous gases, vapors, and toxins. This process involves conducting initial and periodic tests to check atmospheric safety.
  • Personal Protective Equipment (PPE): Specification of the required PPE for all entrants, such as respirators, protective clothing, and fall protection gear.
  • Communication: Establishment of reliable communication methods between entrants and attendants to facilitate constant contact and coordination.


Rescue Plans
A critical component of the confined space permit is the inclusion of detailed rescue plans. These plans ensure that emergency response procedures are clearly defined and practiced. This covers the identification of trained rescue personnel who are on standby and ready to respond immediately, ensures the availability and readiness of rescue equipment, and the step-by-step procedures for safely extracting entrants from the confined space in the event of an emergency

Authorization and Sign-off
The confined space permit to work must be authorized and signed off by a competent person who has assessed the confined space and the proposed work. This person verifies that all safety measures are in place and that the space is safe for entry. The authorization process consists of the initial approval and the continuous monitoring of the status of the operation, ensuring compliance with safety protocols.

Documentation and Record-Keeping
Maintaining records of confined space permits is essential for accountability and future reference. Documentation includes copies of all issued permits, including details of the work performed, safety measures taken, and personnel involved. Aside from that, it also features records of any incidents or near-misses that occurred during the confined space entry, along with an analysis of the causes and corrective actions taken.

Industry-Specific Confined Space Regulations

Different industries encounter unique challenges when it comes to confined space safety due to the varied nature of their operations and the specific environments they work in. Consequently, there are industry-specific standards that address these unique hazards and provide tailored safety protocols. Understanding these standards is crucial for ensuring compliance and safeguarding workers.

Here’s a detailed look at the key confined space regulations, standards, and requirements in different industries:

OSHA General Industry Standard for Permit-Required Confined Spaces
OSHA's Permit Required Confined Spaces standard (29 CFR 1910.146) focuses on permit-required confined spaces and addresses procedures for atmospheric testing, permits, training, and rescue operations. Specifically, this standard states that 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.

Construction and Engineering
The construction and engineering sectors often deal with a dynamic environment where confined spaces can be temporary and change rapidly. Specific standards and regulations include the OSHA 29 CFR 1926 Subpart AA that specifically addresses confined spaces in construction and mandates employers to evaluate the worksite for confined spaces, establish and implement a written permit space program, and ensure proper training and equipment for workers.

In addition, construction projects often require a detailed job hazard analysis (JHA) to identify and control hazards associated with confined spaces, taking into account the changing conditions and the variety of confined spaces that might be encountered.

Maritime and Offshore
Confined spaces in maritime and offshore environments present unique challenges, such as the presence of hazardous atmospheres, limited egress, and the potential for rapid flooding. Relevant standards and regulations include:

  • OSHA 29 CFR 1915 Subpart B: This regulation covers confined and enclosed spaces and other dangerous atmospheres in shipyard employment. It mandates the use of marine chemists or competent persons to evaluate and certify the safety of these spaces.
  • International Maritime Organization (IMO) Standards: IMO guidelines provide a framework for the safe management of enclosed spaces on ships, emphasizing risk assessment, involves permit space entry procedures, and emergency preparedness.
  • Oil and Gas Industry Standards: Organizations like the American Petroleum Institute (API) have specific guidelines for confined space entry in offshore oil and gas operations, addressing unique hazards like hydrogen sulfide (H2S) and explosive atmospheres.


Utilities and Telecommunications
Utilities and telecommunications workers frequently enter confined spaces such as manholes, vaults, and tunnels. The National Electrical Code (NEC) provides guidelines for safe work practices in confined spaces that house electrical equipment, focusing on the prevention of electrical hazards. Organizations like the Telecommunications Industry Association (TIA) and other Utility Service Standards offer guidelines and best practices for confined space entry in telecom and utility infrastructures.

Manufacturing and Processing
Manufacturing and processing industries often involve confined spaces in tanks, silos, reactors, and pits. Organizations like the American Chemical Council (ACC) provide guidelines for confined space entry in chemical manufacturing, focusing on chemical exposure risks, ventilation requirements, and emergency procedures. In addition, the Food and Drug Administration (FDA) and other regulatory bodies provide specific standards for confined space entry in food processing facilities, addressing hazards like carbon dioxide (CO2) from fermentation processes and cleaning chemicals.

 

Training Requirements for Confined Space Work

ppe safety measures in confined space


In confined space operations, worker safety should be the priority. A key element in safe confined spaces involves extensive and comprehensive worker training. Training, along with a deep understanding of relevant standards and regulations, and following best practices can significantly reduce the risks associated with confined space work.

Key training requirements include:

  • Hazard Recognition: Educating workers on the specific hazards they may encounter in confined spaces, such as toxic gases, oxygen deficiency, and physical dangers.
  • Safety Procedures: Instructing workers on proper entry and exit procedures, the use of personal protective equipment (PPE), and the operation of ventilation and monitoring equipment.
  • Emergency Response: Training workers and attendants on emergency procedures, including the use of rescue equipment and the steps to take in the event of an emergency.
  • Practical Exercises: Conducting hands-on training exercises to simulate confined space entries and rescues, helping workers and attendants to practice and reinforce their skills.


In addition to confined safety training, the Occupational Safety and Health Administration has specific training requirements for various roles involved in confined space operations:

Confined Space Entrants
Confined space entrants have the duty to follow all safety procedures and use the required personal protective equipment (PPE). Entrants are responsible for being aware of the hazards, continuously monitoring their environment, and maintaining communication with the attendant at all times. To fulfill these responsibilities effectively, entrants must be trained in hazard recognition, safe entry and exit procedures, the proper use of PPE, and emergency protocols.

Confined Space Attendants
The primary duties of confined space attendants include remaining outside the confined space during entry operations, monitoring the safety of entrants, and maintaining constant communication with them to ensure their safety. To effectively carry out these responsibilities, attendants must undergo thorough training to understand the specific hazards associated with confined spaces, effectively use communication equipment, and perform emergency response duties.

Confined Space Supervisors
Confined Space Supervisors are tasked with overseeing confined space operations to ensure that all safety procedures are followed and that entries are conducted safely. To effectively fulfill these duties, supervisors must receive comprehensive training in hazard recognition, permit systems, emergency response, and the overall management of confined space operations.

Confined Space Rescue Plans
OSHA mandates that employers develop and implement rescue plans tailored to each specific confined space. These plans must outline procedures for summoning rescue and emergency services and using rescue equipment effectively. Rescue personnel must be thoroughly trained to perform assigned rescue duties, use of rescue equipment, rescue techniques, and the specific hazards associated with confined spaces. To ensure preparedness, regular rescue drills should be conducted, enabling rescue teams to respond quickly and effectively in an emergency.

 

FAQs

What are 10 examples of confined spaces?

Confined spaces include tanks, silos, storage bins, hoppers, vaults, pits, manholes, tunnels, equipment housings, ductwork, and pipelines. These spaces typically have limited entry and exit points and are not designed for continuous occupancy.

What is the oxygen limit in a confined space?

The oxygen level in a confined space must be maintained between 19.5% and 23.5% to ensure a safe working environment. Levels below or above this range can be hazardous and require immediate corrective action.

What are the four gases in confined space?

The four primary gases of concern in confined spaces are oxygen, hydrogen sulfide (H2S), carbon monoxide (CO), and methane (CH4). These gases can create hazardous conditions, including oxygen deficiency, toxicity, and explosive atmospheres.

What is the maximum duration of a space permit?

The maximum duration of a confined space permit is typically limited to one work shift. This ensures that conditions within the space are reassessed regularly and that safety measures remain effective throughout the entry period.

How to control confined space?

Controlling confined space involves several key steps: conducting a thorough risk assessment, implementing proper ventilation, using appropriate personal protective equipment (PPE), continuously monitoring atmospheric conditions, and ensuring effective communication and emergency preparedness. Following these measures helps mitigate risks and ensures worker safety.

The material provided in this article is for general information purposes only. It is not intended to replace professional/legal advice or substitute government regulations, industry standards, or other requirements specific to any business/activity. While we made sure to provide accurate and reliable information, we make no representation that the details or sources are up-to-date, complete or remain available. Readers should consult with an industrial safety expert, qualified professional, or attorney for any specific concerns and questions.

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Author: Herbert Post

Born in the Philadelphia area and raised in Houston by a family who was predominately employed in heavy manufacturing. Herb took a liking to factory processes and later safety compliance where he has spent the last 13 years facilitating best practices and teaching updated regulations. He is married with two children and a St Bernard named Jose. Herb is a self-described compliance geek. When he isn’t studying safety reports and regulatory interpretations he enjoys racquetball and watching his favorite football team, the Dallas Cowboys.