What is a Confined Space? Understanding Confined Space Hazards, Types and Regulations

Key Takeaways

• Confined spaces should be assessed thoroughly, with any permit space identified based on hazards such as atmospheric risks, engulfment, or structural dangers.

• Workers must be trained to recognize and respond to hazards that pose an immediate or delayed threat, ensuring safe operations and adherence to safety protocols.

• Employers must implement adequate control measures, such as ventilation, isolation, and monitoring, to maintain safe working conditions in confined spaces.

• Entry is only permitted when acceptable entry conditions are verified by atmospheric testing and approved by an entry supervisor to ensure compliance with safety standards.

• Rescue plans must be established, and trained personnel should be available to perform assigned rescue duties effectively in case of emergencies.

What Is Confined Space?

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, yet are not designed for continuous human occupancy. 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, products, chemicals, etc. 

  • 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.

Examples of Confined Spaces

Confined spaces can vary widely in shape, size, and purpose. The diverse range of confined spaces highlight the importance of understanding the unique hazards associated with each. Some common examples include:

• • Tanks and Vessels: Used in industries like oil and gas, chemical processing, and water treatment, tanks are confined spaces often requiring maintenance or inspection.

  • Manholes and Sewers: Found in urban areas, these spaces are essential for utility maintenance but are hazardous due to limited ventilation and potential exposure to toxic gases.

  • Silage Bunkers and Grain Bins: Frequently encountered in agricultural settings, these spaces pose risks of engulfment and suffocation.

  • Boilers: Used in power plants and industrial facilities, boilers are confined spaces with elevated risks of heat stress and oxygen depletion.

  • Tunnels and Pipelines: Used for transportation or utility purposes, tunnels and pipelines often require workers to operate in enclosed, potentially hazardous conditions.

  • Underground Vaults: Commonly used for electrical or telecommunications infrastructure, vaults can contain harmful gases or lack oxygen.

  • Excavations: Although not classified by OSHA as permit-required confined spaces, excavations can present typical confined space hazards. This includes excavation activities used in civil work, burying or inspecting underground utilities, or new construction.

 

Confined Space Hazards

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 confined space hazards:

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, drowning, 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.

Types of Confined Spaces

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

Non-Permit Confined Spaces

A non permit confined space refers to work areas that do 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 an entry permit 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 Spaces 

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 to engulf an entrant.

  • Has an internal configuration such that an entrant could lead to the surrounding and effective capture by converging walls or by a floor that slopes downward and tapers to a smaller cross-section.

  • Contains any other recognized serious safety or health hazard.

In addition to the risks mentioned above, other control permit space hazards include:

• • Fall hazards, such as unprotected edges or slippery surfaces that increase the risk of falling.

  • Electrical hazards, including live wires or exposed electrical components that pose a risk of shock.

  • Mechanical hazards, like moving parts of machinery that can cause entanglement or crushing.

  • Hot work hazards, including welding or cutting that may cause sparks, heat, or fire risks.

This type of confined space environment requires a permit that specifies the work to be done, the personnel involved, and the confined space 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 confined space but have sufficient safeguards in place to allow for a less stringent entry procedure. For instance, if a particular 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.

Confined Space Standards and Regulations

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 employee safety.

The OSHA provides comprehensive standards and regulations to protect workers who must enter confined spaces. 

General 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, as well as working closely with local or third party rescue teams.

  • 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 

A confined space permit to work system is a formal process used to authorize and control entry into confined spaces where there are potential hazards. This system is designed to protect workers by requiring a written or printed document before anyone enters a confined space. The entry permit typically outlines:

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 identify 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

The permit must list all authorized personnel entering the confined space, including the attendants monitoring from outside. It should also name the supervisors overseeing permit space entry operations to control entry and provide assistance, especially in cases of emergency or during non entry rescues.

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:

1. Isolation of Hazards: Steps to isolate or control all hazardous energy sources, such as lockout tagout procedures on electrical systems or shutting down machinery.
2. Ventilation: Procedures for ensuring adequate ventilation within the confined space to maintain safe atmospheric conditions.
3. 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.
4. Personal Protective Equipment (PPE): Specification of the required PPE for all entrants, such as respirators, protective clothing, and fall protection gear.
5. Communication: Establishment of reliable communication methods between entrants and attendants to facilitate constant contact and coordination.

Rescue Plans

A confined space permit must include detailed rescue plans, identifying trained rescue personnel, available retrieval systems, and step-by-step procedures. These plans prepare the rescue team to act quickly during emergencies, including permit space rescues or non permit confined space incidents.

Authorization and Sign-off

A competent person must authorize the confined space permit, confirming all safety measures are in place. This person is typically the CS Entry Supervisor who assesses the confined space, monitors the operation, and approves both the initial entry and ongoing compliance with safety protocols throughout the work. 

Documentation and Record-Keeping

Confined space permits must be documented for accountability and future reference. Records should include work details, employee safety measures, personnel involved, and any incidents or near-misses, along with corrective actions.

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 which 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, involving 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.

 

Confined Space Training

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:

1. Hazard Recognition: Educating workers on the specific hazards they may encounter in confined spaces, such as toxic gases, oxygen deficiency, and physical dangers.
2. Safety Procedures: Instructing workers on proper entry and exit procedures, the use of PPE, and the operation of ventilation and monitoring equipment.
3. 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.
4. 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. This training strategy is designed to ensure workers are well aware and equipped with the right knowledge and skills to work safely in confined spaces.

Working in Confined Spaces: Safety Tips and Guidelines

Ensuring worker safety in confined spaces, as shown above, requires strict adherence to established guidelines, effective planning, and the use of appropriate equipment. This section provides key safety tips and practices for entering, monitoring, isolating, and responding to emergencies in confined spaces.

Confined Space Entry 

Safe entry into a confined space begins with thorough planning and hazard identification. A pre-entry assessment should identify atmospheric, structural, and environmental risks, determining whether the space is a non-permit or permit-required confined space. For permit-required spaces, obtaining the necessary permits and ensuring all hazards are controlled and documented is essential. This preparatory step ensures that risks are minimized before workers enter the confined space.

Effective communication and training are also critical for safe operations. Clear communication protocols must be established between entrants, attendants, and supervisors, with reliable systems like two-way radios in place for continuous contact. Additionally, all personnel must be thoroughly trained in entry procedures, hazard identification, and emergency response to ensure that they are equipped to handle potential risks and maintain safety throughout the task.

Confined Space Monitoring 

Confined space monitoring is crucial for identifying and addressing hazardous conditions before and during operations. Atmospheric testing should be conducted before and during entry to measure oxygen levels, detect toxic gases, and identify flammable substances. Continuous monitoring is mandatory in hazardous spaces, as required by OSHA’s 29 CFR 1910.146(d)(5), to ensure worker safety throughout the task.

The use of real-time sensors, such as portable gas detectors with audible and visual alarms, enhances safety by providing immediate alerts about changing conditions. Regularly logging and updating monitoring results helps maintain a clear record of the environment’s status, ensuring any emerging risks are quickly addressed and workers remain protected.

Confined Space Isolation 

Confined space isolation aims to control energy sources and prevent accidental exposure to hazards. A key step is implementing the lockout/tagout (LOTO) process, which involves de-energizing machinery and electrical systems connected to the confined space, in compliance with OSHA’s 29 CFR 1910.147 standard for controlling hazardous energy. This prevents the unintended activation of equipment that could endanger workers.

Additional isolation measures include blocking access points by sealing valves and disconnecting pipelines to stop hazardous substances from entering the space. Physical barriers and clear signage should also be used to prevent unauthorized access, ensuring that only trained and authorized personnel enter the confined space. These precautions significantly reduce risks and create a controlled work environment.

Essential Confined Space Equipment

Working in confined spaces demands the use of specialized tools and equipment to ensure safety, enhance efficiency, and respond effectively to emergencies. These tools mitigate risks associated with confined space entry, monitoring, isolation, and rescue, providing workers with the means to complete tasks safely.

1. Personal Protective Equipment (PPE): Includes items like hard hats, gloves, respirators, and protective suits to shield workers from physical, chemical, and atmospheric hazards.
2. Gas Detection Monitors: Portable devices used to continuously test for oxygen levels, toxic gases, and flammable vapors, providing immediate alerts for unsafe atmospheric conditions.
3. Ventilation Systems: Blowers and exhaust fans that improve air circulation, remove contaminants, and maintain safe oxygen levels in confined spaces.
4. Retrieval Systems: Comprising tripods, winches, and full-body harnesses, these systems facilitate safe entry, exit, and rescue operations in confined spaces.
5. Lighting Equipment: Explosion-proof and portable lighting ensures visibility in dark or hazardous environments without posing additional safety risks.
6. Communication Devices: Two-way radios and hands-free communication systems enable constant contact between workers inside and outside the confined space, ensuring coordination and rapid response in emergencies.
7. Emergency Rescue Equipment: Includes self-contained breathing apparatus (SCBA), rescue ropes, and stretchers to facilitate efficient response in case of an emergency.

Confined Space Rescue Plan 

Rescue procedures can vary depending on the nature of the confined space and the hazards involved. Below are the types of confined space rescue procedures:

• • Self-Rescue: Workers can evacuate the confined space on their own when early warning signs or alarms signal the need for immediate exit.

  • Non-Entry Rescue: Rescuers use equipment from outside the particular permit space to retrieve the worker without having to enter the hazardous environment.

  • Entry Rescue: A trained rescue team enters the confined space to retrieve the worker when other rescue methods are not possible.

Facilitating Non Entry Rescue

Non entry rescue is preferred whenever possible, as it minimizes the risks to rescuers. Here are key elements to facilitate non entry rescue in confined spaces:

1. Harness: Each worker must wear a properly fitted harness that connects to the retrieval system for quick and safe extraction.

2. Retrieval Line: This line attaches to the worker’s harness, allowing the rescue team to pull them out without needing to enter the space.

3. Mechanical Device: Devices like winches or tripods are used to assist in lifting the worker, especially when vertical entry or exit is required.

4. Assessment: Before beginning the rescue, the rescue team assesses the situation to determine the safest method for retrieval based on the space and hazards present.

5. Backup Plan: A backup plan should always be in place in case the initial non-entry rescue method is not successful or additional hazards arise during the rescue.

Confined space rescues can be performed by trained personnel, such as an in-house rescue team, a contracted rescue service, or local emergency services. For permit space rescues, the prospective rescue service's ability to handle the hazards must be evaluated regularly.

Choosing a Confined Space Rescue Service

Selecting the right rescue service is key to managing confined space emergencies effectively. Whether it's for permit space rescues or non-permit confined space environments, it’s important to assess the capabilities of any prospective rescue team.

OSHA standards 1910.146 and 1926.1211 outline performance requirements for rescue teams. The evaluation process involves two key steps: an initial assessment and a performance evaluation.

The initial assessment examines the rescue service's technical skills, training documentation, personnel count, availability, and timeliness. It also verifies compliance with OSHA 1910.146(k)(2) regarding personal protective equipment, training, and practice in representative spaces.

Performance evaluation involves observing the rescue team in action during simulated scenarios at the employer's site. This hands-on assessment helps gauge their practical capabilities in permit space rescues.

A thorough evaluation of the prospective rescuer's ability helps prevent accidents and saves lives. It's critical to select rescue and emergency services capable of handling specific rescue related tasks at your facility, including non entry rescue methods and the use of retrieval systems when appropriate.

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, making them not ideal for continuous employee occupancy. Workers are mandated not to stay beyond the permissible exposure limit.

What is the maximum duration of a space permit?

The maximum duration of a confined space permit is typically limited to one work shift, as indicated in the employer's permit space program. 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 before and during entry (with and without ventilation), and ensuring effective communication and emergency preparedness. Following these measures helps mitigate risks and ensures worker safety.