Confined Space Risk Assessment (Hazard Assessment)
| Potential Hazard | Signs, Symptoms, Dangers of Exposure | Techniques to Control Hazards |
| Low oxygen (<19.5%)Caused by:
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Impaired attentionthinking-coordination, rapid fatigue, dizziness, nausea, vomiting, loss of consciousness, asphyxiation |
Spaces that contain less than 19.5% oxygen may only be entered as an IDLH Entry, refer to IDLH Confined Space Entry Procedure for specific requirements. • All connections to the space must be isolated sufficiently to prevent ingress of contaminants. • Any space that presents a low oxygen condition must be purged with air to increase oxygen levels, and then ventilated with fresh air. • Flammable gases must be purged from the equipment using an inert (i.e., nitrogen, steam), then the system must be purged with fresh air as above. • The space must be checked for acceptable atmosphere across and along the full length and breadth of the workspace, prior to entry. • All piping connected to the space must be checked for oxygen levels as the piping becomes exposed. • Continuous atmosphere monitoring required if initial atmosphere readings (after purging) are < 20.5% O2. • Periodic atmosphere checks are required after every break in the work activities. Consider more frequent checks (i.e., hourly) • Consider continuous ventilation as a precaution; however, if continuous ventilation is required to maintain oxygen levels above 19.5%, continuous oxygen monitoring is required. |
| High oxygen (>23.5%) | Cough, chest pain, gas accelerates combustion: saturation with oxygen and burning of incompatible material |
Spaces that contain more than 23.5% oxygen may not be entered. • All connections to the space must be isolated sufficiently to prevent ingress of oxygen. • Any space that contains an oxygen-enriched fluid must be purged with air to remove high oxygen levels, and then ventilated with fresh air. • The space must be checked for acceptable atmosphere across and along the full length and breadth of the workspace, prior to entry. • All piping connected to the space must be checked for oxygen levels as the piping becomes exposed. • Continuous atmosphere monitoring required if initial atmosphere readings (after purging) are > 21.1% O2. • Periodic atmosphere checks are required after every break in the work activities. Consider more frequent checks (i.e., hourly) • Consider continuous ventilation as a precaution; however, if continuous ventilation is required to maintain oxygen levels below 23.5%, continuous oxygen monitoring is required. |
| Flammable gas/vapor (>10% LEL) | Fire, explosion, burns, asphyxiation. | Spaces that contain more than 10% LEL may not be entered. • All connections to the space must be isolated sufficiently to prevent ingress of contaminants. • Flammable gases must be purged from the equipment using an inert (i.e., nitrogen, steam), and then the system must be purged with fresh air as with Low Oxygen Hazard. • The space must be checked for acceptable atmosphere across and along the full length and breadth of the workspace, prior to entry. • All piping connected to the space must be checked for flammable levels as the piping becomes exposed. • Reasonable attempts should be made to purge LEL to <1%. If purging cannot achieve <1%LEL, but can maintain <10% LEL, continuous monitoring is required and space must be evacuated if LEL increases by 2% from baseline entry readings. Increase frequency of logging atmosphere results (i.e., every 15-20 minutes). • Periodic atmosphere checks are required after every break in the work activities. Consider more frequent checks (i.e., hourly) • Consider continuous ventilation as a precaution; however, if continuous ventilation is required to maintain LEL levels below 10%, continuous LEL monitoring is required. |
| Toxic Vapors | Impaired attentionthinking-coordination, rapid fatigue, dizziness, nausea, vomiting, loss of consciousness, tissue/organ damage, poisoning. Consult MSDS for specific contaminant. |
Spaces that contain toxic contaminants greater than the IDLH limit(s) for that specific contaminant may only be entered as an IDLH Entry, refer to IDLH Confined Space Entry Procedure for specific requirements. • All connections to the space must be isolated sufficiently to prevent ingress of contaminants. • Toxic gases should be purged from the equipment using air (if they are not flammable) or an inert (if they are flammable), and then the system must be purged with fresh air. • The space must be checked for acceptable atmosphere across and along the full length and breadth of the workspace, prior to entry. • All piping connected to the space must be checked for contaminants as the piping becomes exposed. • Periodic atmosphere checks are required after every break in the work activities. Consider more frequent checks (i.e., hourly) Spaces containing toxic contaminants >25% of the PEL may only be entered after implementing controls to ensure that Entrants will not be exposed over the PEL. Consider: • Continuous ventilation; • Continuous atmosphere monitoring; • Limiting exposure time; and/or •Respiratory protection |
| Combustible Dust (>LEL) | Fire, explosion, burns, asphyxiation, respiratory irritation, eye irritation. |
Spaces that contain more than the LEL of combustible dust may not be entered. Generally, this can be identified where the combustible dust limits visibility to <5 feet. • All connections to the space must be isolated sufficiently to prevent ingress of contaminants. • Combustible dusts must be purged and ventilated from the equipment using an inert (i.e., nitrogen), and then the system must be purged with fresh air as with Low Oxygen Hazard. • The space must be checked for acceptable atmosphere across and along the full length and breadth of the workspace, prior to entry. • Periodic atmosphere checks are required after every break in the work activities. Consider more frequent checks (i.e., hourly) •Consider continuous exhaust ventilation as a precaution. |
| Irritant dust (i.e., Rockwool) | Irritation to eyes (redness), skin (rash), respiratory system (cough, sore throat). Consult MSDS for specific contaminant. |
Spaces containing irritant dusts >25% of the PEL may only be entered after implementing controls to ensure that Entrants will not be exposed over the PEL. Consider: • Respiratory protection (refer to MSDS & Respiratory Protection Standards for specific requirements for specific contaminants). • Exhaust Ventilation • Skin protection • Specify controls based on contaminant: |
Physical Hazards |
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| Engulfment by collapsing loose solid materials (i.e., rockwool, bulk chemicals, dirt) |
Injury from weight of loose material, loss of consciousness, asphyxiation. |
• Entry area must be shored up as constructed. • Solid materials may have to be removed from the area above the space to prevent hazardous exposure to workers. • Implement Excavation Procedure requirements, as applicable. • Implement Fall Protection Procedure, as applicable |
| Engulfment from fall into solids and powders below work space | Injury from weight of loose material, loss of consciousness, asphyxiation. |
• Entry area must be shored up as constructed. • Solid materials may have to be removed from the area below the space to prevent hazardous exposure to workers. • Implement Fall Protection Procedure, as applicable •Barricades, scaffolding, temporary floors/walls |
| Engulfment from water or other liquid |
Drowning | • Lockout/Tagout and Energy Isolation procedures. • Water/liquid may have to be removed from the area below the space to prevent hazardous exposure to workers. • Implement Fall Protection Procedure, as applicable • Implement Excavation Procedure requirements, as applicable. •Barricades, scaffolding, temporary floors/walls |
| High Temperature | Heat exhaustion, heat stroke, excessive sweating, headaches, dizziness/light headedness, weakness, mood changes (irritable, or confused/can’t think straight), vomiting/throwing up, fainting/passing out, pale clammy skin, pale dry skin, red skin |
• Ventilation • Break periods • Provide liquids at entry point |
| Low Temperature | Red skin, white skin, frostbite, hypothermia |
• Provide heat source (consider hazards created by adding a heater) • Break periods •Require PPE |
| Fall from height | Abrasions, contusions, broken bones, internal injuries |
• Barricades, scaffolding, temporary floors/walls • Implement Fall Protection Procedure, as applicable |
| Mechanical hazard | Abrasions, contusions, broken bones, internal injuries |
• Lockout/Tagout and Energy Isolation procedures. |
| Configuration hazard of confined space |
Entrapment, abrasions, contusions, broken bones, internal injuries |
• Barricades, scaffolding, temporary floors/walls • Rescue Plan accounts for configuration of space |
| Electric Shock | Tingling to pain, shortness of breath to respiratory arrest, cardiac arrest |
• Lockout/Tagout and Energy Isolation procedures. • All electrical equipment must be inspected before every use. • All electrical equipment must be properly grounded. • Extension cords that supply power to workers in the confined space must be kept out of the way of areas that may cause damage to the cords. • Electrical utility equipment and power tools must be low voltage (e.g., 30 volts or less) or protected by Ground Fault Circuit Interrupter (GFCI) located outside the space. |
| Radioactive sources |
No visible signs or symptoms of lowlevel radioactive exposure. Entry planning must review the entry site for sources of radiation such as radioactive source based level gauges or work to be performed such as x-ray testing. |
• Lock out shutters on radioactive level gauges. • Isolate the work area (barricade and post signs) when x-ray testing is being performed.NOTE: Radiation hazards often require special considerations due to the hazards and specific regulatory requirements. Such requirements may include involvement of a certified specialist (i.e., Radiation Safety Officer), monitoring for radiation with the appropriate meter, or other specific work practices. You must consult your local radiation plans and procedures as well as local or national legislation for proper isolation and control requirements for radioactive sources. |
| Noise | High levels of noise within the space may interfere with communications. Extended overexposure to high noise levels could result in hearing loss and ringing in the ears |
• Isolate or insulate the noise source, if possible. • Hearing protection • Take into account high noise levels when planning Attendant/Entrant communication. Alternatives to natural voice communication may be required (i.e., radio, visual, etc.) |
| Chemical Exposure or reaction |
Consult MSDS for specific contaminant. |
• Clean space prior to entry • PPE • Specify controls based on contaminant: |
Live Line Hazards |
| Live Process Lines contained within a space. |
Signs and symptoms will vary based upon the material contained within the live line. Check the appropriate hazard (above) based on the contaminant. Live lines also pose a pressure release hazard, which may injure workers. |
Methods used to control the hazards associated with live lines can vary. In the order of preference, typical methods include: 1. Isolate the live lines to eliminate the hazard; 2. Consider the space an IDLH entry and implement procedure 25-010542 “Requirements for IDLH Atmospheres”; 3. Lower the pressure of the process to reduce the leak rate or possibility of line failure; 4. Provide adequate ventilation and continuous atmospheric monitoring to assure safe entry conditions • Evaluate each hazard above for the content of the live line: o Low Oxygen Hazard o High Oxygen Hazard o Flammable Gas/Vapor Hazard o Toxic Vapor Hazard oEngulfment Hazard |
| Work Activity Hazards | ||
| Loss of utilities | Loss of purge, ventilation, or lighting |
• Lock and tag utility source. Provide backup lighting for the Attendant should an external power failure occur (e.g., power company supply). |
| Hot Work | Fire, explosion, burns, toxic fume exposure (Eye irritation, throat irritation, dizziness, nausea or vomiting) |
• Continuous atmosphere monitoring is required for oxygen and LEL. • Evaluate ventilation and consider continuous CO monitoring (see Toxic Vapor Hazard) • Implement Hot Work precautions indicated in the Safety Work Permit Procedure • Evaluate Noise Hazard • Evaluate Flammable Gas Hazard |
| Permiter Hazards caused by hazardous atmospheres migrating outside of the space. |
Fires, burns, asphyxiation |
• Installation of a physical barrier is required around the entry point and work area which prohibits or otherwise controls access to the confined space entry point. • Install the appropriate warning signs (i.e., Danger: Under N2 purge – potential asphyxiating atmosphere), not generic confined space warning signs at the permiter barrier. • Special precautions must be taken to train and equip the Attendant to work in and around this area (i.e., one-on-one coaching/training, supplied breathing air, atmospheric monitoring outside the space). |