Confined spaces

Safety by Topic

If you have any areas that:

  1. Are large enough so an employee can fully enter and work,

  2. Have restricted entry or exit, and

  3. Are not primarily designed for continuous human occupancy,

You have a confined space, and you must identify them in your accident prevention program then evaluate each space as a potential permit-required confined space.

ALL confined spaces must be considered permit-required unless they have been evaluated and determined otherwise.

Permit-required confined spaces

A permit-required confiend space is confined space that has one or more of the following charactersistics capable of causing death or serious physical harm:

  • Contains or has the potential to contain a hazardous atmosphere;

  • Contains a material that has the potential for engulfing someone who enters;

  • Has an internal configuration that could allow someone entering to be trapped or asphyxiated by inwardly converging walls or by a floor, which slopes downward and tapers to a smaller cross-section; or

  • Contains any physical hazard. This includes any other recognized serious health or safety hazard including engulfment in a solid or liquid material, electrical shock, or moving parts.

  • Contains any other recognized serious safety or health hazard that could either:

    • Impair the ability to self-rescue; or

    • Result in a situation that presents an immediate danger to life or health.

If you have identified your spaces to be permit-required, you must have a plan to protect employees during entry.

FLOW CHART TO DETERMINE STEPS OF PERMIT REQUIRED CONFINED SPACE ENTRY

Examples

These are not comprehensive lists.

  • adhesive mixers

    adhesive tanks

    aggregate bins

    air pollution equipment including Air Scrubbers

    aircraft wing fuel tanks

    aneraerobic digesters

    attics autoclaves

    bag houses

    balers

    bark blower

    bar screen enclosures

    bins blast furnaces

    blast recovery pits

    bleach tanks 

    boilers bridge box girders and enclosed beams

    caustic soda tanks

    caissons

    cesspools and pits

    chimneys and stacks

    coal bunkers

    cooling towers

    chillers

    clay hoppers

    composters

    compactors

    controlled atmosphere (CA) rooms when sealed

    concrete mixers

    conveyor enclosures

    crane legs

    crawl spaces and attics

    crude oil tanks crushers

    cyclones

    degreasers

    digesters

    dip tanks

    dropped ceilings

    dikes

    duct work

    dust collectors

    drains

    drums

    drying ovens 

    excavations and trenches

    fermenters

    furnaces

    garbage trucks

    grease traps

    heating and cooling ventilation

    ductwork

    hoppers

    hydrapulpers

    hydrogen reformer furnace

    ice houses

    incinerators

    irrigation dam outlet towers

    irrigation siphons

    kilns

    kettles

    manholes

    manure pits

    mixers and mix tanks

    mills ovens

    pressure vessels

    precipitators

    pits

    pipes and pipelines

    rail tank cars

    reaction and reactor veseels

    reservoirs

    sanitary

    storm sewer and waste water systems

    scrubbers

    septic tanks

    shafts

    shredders

    silos and hoppers

    sludge pits

    sulfuric acid tanks

    tanks and vats

    tanker vessels

    tunnels vaults

    water towers

    wind machines

  • Processes that consume or displace oxygen include:

    • Activated charcoal

    • Rusting metal

    • Fermentation

    • Welding

    • Fires

    • Decaying organic material (and methane production)

    • Inert gases: argon (Ar2), carbon dioxide (CO2) including dry ice and chemical reactions producing carbon dioxide (CO2), helium (He2), nitrogen (N2). Some inert gases are used to control a potential flammable atmosphere. The inerting of the space with one of these gases will create an oxygen deficient atmosphere.

  • Enriched oxygen concentrations will increase the flammability of many materials including clothing.

    • Failure to inadequately blank or disconnect oxygen lines

    • Leaking oxygen hoses or pipes

    • Use of oxygen instead of air for ventilation

  • Be sure to review the exposure limits found in WAC 296-841 Air Contaminants. Additionally learn about Immediately Dangerous to Life or Health (IDLH) atmospheres here.

    • Ammonia Arsene

    • Carbon Monoxide (CO)

    • Burning or combusting fuels (incomplete combustion) for example: Gas heaters, stoves, and grills Portable generators Propane powered industrial trucks (forklifts) Internal combustible engines: vehicles, heavy equipment

    • Iron processing

    • Welding Poorly ventilated mines

    • Cyanide

    • Chlorine gas (Cl2)

    • Chlorine dioxide (ClO2)

    • Hydrogen Sulfide (H2S)

    • Oxides of nitrogen (NOX)

    • Carbon monoxide (CO)

    • Cleaning and degreasing chemicals: Hydrogen peroxide, Solvents, Halogenated degreasing agents like methylene chloride

    • Chemical reactions that result in the formation of toxic materials

    • Process chemical residues

  • Surrounding, suffocating, drowning, and bridging materials can engulf employees.

    • Water

    • Corn syrup

    • Chocolate

    • Wine

    • Beer

    • Plastic

    • Sewage

    • Grain

    • Sawdust

  • Internal configuration hazards include spaces with sloping walls or floors tapering to a smaller cross section trapping or asphyxiating a worker.

    • Silos

    • Hoppers

    • Biological hazards

      • disease causing organisms

      • poisonous spiders or snakes

    • Chemical reactions generating heat or reactive material (explosions, unstable or reactive materials).

    • Combustible dust and particulates

    • Energy

    • Electrical

    • Extreme temperatures

    • Falling objects, coke, scale, concrete, baled materials, tools and equipment)

    • Falls from heights

    • Flowable energy like steam, gas

    • Gravity

    • Hydraulic

    • Ignition sources

      • non-intrisically safe equipment (en exposed lightbulb in a flammable atmosphere)

    • Mechanical hazards

    • Metal dusts

    • Moving parts (augers, agitators, conveyors, crushers, tumblers, mixers, rakes)

    • Organic dust

    • Pneumatic

    • Pressurized lines

    • Radiation (Ionizing or non-ionizing)

    • Spark producing equipment and processes

      • welding

      • cutting

      • burning

      • torching

      • grinding

      • space heaters

      • static discharge

      • transferring liquids without bonding or grounding

    • Steam Stored energy

    • Systems under pressure

    • Water