Confined Spaces

Hazards in the Workplace
Fact Sheet: Confined spaces
Confined spaces are a major hazard to workers who are required to work
within these areas. Confined spaces include, but are not limited to, storage
tanks, process vessels, pits, vats, vaults, sewage digesters, sewer silo,
tunnels, manholes, utility vaults, pumping stations, enclosed grit chambers or
similar types of enclosure with limited access and without proper ventilation.
Entry into confined spaces may be for the purpose of inspection, testing of
equipment, maintenance (repair and cleaning) or an emergency. Chapter 2 of
the NSW OHS Regulations 2001:Places of work—risk management and
other matters imposes obligations on an employer to identify foreseeable
hazards that may arise from the conduct of the employer’s undertaking.
It is an employers responsibility to assess the risks of those hazards and to
eliminate the risks or, if not reasonably practicable to do so, to control the
risks. Chapter 4 part 4.3 Division 9 of the NSW OHS Regulations specifically
defines what control measures must be taken prior to entering a confined
space.
What is a confined space
•
A confined space means an enclosed or partially enclosed space that:
•
Is not intended or designed primarily as a place of work.
•
Is at atmospheric pressure while persons are in it.
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May have an atmosphere with potentially harmful contaminants, an
unsafe level of oxygen, or stored substances that may cause
engulfment.
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May (but not need) have restricted means of entry and exit.
Confined spaces are normally entered to perform necessary industrial tasks.
The list below represents some typical reasons for entering confined spaces.
• Cleaning to remove waste or sludge
• Physical inspection of plant or equipment
• Installing pumps, motors or other equipment
• Maintenance work painting, sand blasting or applying surface coatings
• Reading of meters, gauges or dials
• Repair work (e.g. welding or cutting)
• Installing, repairing or inspecting cables (e.g. telephone, electrical or fibre
optic)
• Tapping, coating or testing of piping systems (e.g. steam, water or sewage)
• Constructing a confined space (e.g. industrial boiler)
• Rescuing people who are injured or overcome by fumes
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You need to check if the work can be done another way so that entry or
work in confined spaces is avoided. Better work planning or a different
approach can reduce the need for confined space working. Ask yourself if
the intended work is really necessary, or could you:
Modify the confined space itself so that entry is not necessary;
Can the work be done from outside, for example:
Blockages can be cleared in silos by use of remotely operated rotating flail
devices, vibrators or air purgers;
Inspection, sampling and cleaning operations can often be done from outside
the space using appropriate equipment and tools; remote cameras can be
used for internal inspection of vessels.
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Examples of confined space hazards
Confined spaces are particularly dangerous because the hazards may not be
immediately apparent. The dangers of confined spaces can include:
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Biological hazards, such as bacteria
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Exhaust gases
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Flammable gases
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Low oxygen levels
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Noise
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Extremes of temperatures
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Falling objects from height
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Slips, trips and falls
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Manual handling
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Electricity
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Radiation
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Poor access/egress
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Visibility
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Hot work within the space.
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Engulfment
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Entrapment
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Risk of engulfment if stored substances collapse
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Toxic gases
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Solids, such as wheat.
TRAINING
Proper training, careful preparation and good judgment are essential to safe
confined space entry. The employer is required to provide initial and refresher
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training to equip employees with the understanding, skills and knowledge
necessary to perform the confined space entry safely.
Training MUST be provided to each affected worker before performing
assigned duties in confined spaces. Entrants, attendants, supervisors and
rescuers require different levels of training according to their specific duties
and responsibilities.
Identifying Hazards and Assessing The Risk
The NSW Occupational Health and Safety Act 2000 requires employers (or
persons in control of the place of work) to:
1. Identify the hazards associated with working in the confined space.
2. Assess the risks (i.e. determine if the hazards are significant).
3. Control the risks by:
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Elimination;
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Substitution;
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Isolation;
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Engineering controls;
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Administrative controls; and
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Use of personal protective equipment.
The Act gives detailed information on hazard identification and risk
assessment.
Some of the things that should be considered include:
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Oxygen-deficient atmospheres, which can cause brain damage and
death. Oxygen deficiency can be caused by rust, fire, absorption by
grain or soils, consumption by bacteria, and displacement by another
gas.
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Toxic atmospheres, containing gases, vapours, dusts or fumes that
have poisonous effects on the body. Cleaning, painting or welding may
produce dangerous vapours or fumes.
•
A flammable or explosive atmosphere, containing flammable gases,
vapours or dusts which could be ignited by a spark or open flame. The
risk of explosion or spontaneous combustion is increased if an oxygenenriched atmosphere exists (where the oxygen content is greater than
23.5%).
•
Engulfment results when a substance, liquid, or solid flows around a
person and encloses them, hindering their ability to escape and often
making it impossible for them to breathe because they become
immersed in the substance. A sudden release of water into a confined
space might cause engulfment. A sudden release of sawdust, sand, or
grain may also cause engulfment.
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Entrapment can occur in any space that has an internal configuration
such that an entrant could be trapped or asphyxiated by inwardly
converging walls or by a floor that slopes downward and tapers to a
smaller cross section.
Engulfment and entrapment are serious health and safety hazards that
require the highest level of standby services, specific controls such as
lifelines, and an entry permit.
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Operation of moving parts, e.g. being trapped or crushed by augers,
mixers, agitators or conveyor belts).
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Uncontrolled introduction of steam, water, or other gas or liquid.
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Control Measures
Preventing injury and death in the workplace requires identifying confined
spaces and the type of work performed inside them. Your Union can offer
information and advice. To reduce the risks:
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Whenever possible, eliminate the need for anyone to go inside the
confined space - for example, use mechanical aids instead.
•
Find out what is in the confined space before planning entry.
•
Assess the air in the confined space. This should be done if you
don’t know for certain what’s been in there in the past. Do not
assume it is safe.
•
Devise safety procedures for working inside the confined space.
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Make sure that any cleaning compounds or equipment used in the
confined space are properly assessed.
•
Make sure anyone going into a confined space has appropriate
protection.
•
Devise emergency and rescue procedures.
•
Rehearse emergency and rescue procedures regularly.
•
Thoroughly train the people who work inside the confined space.
Monitoring for atmospheric hazards
Air monitoring must be conducted before entry to determine if acceptable
entry conditions exist in the space. It may be possible to increase the number
of openings and therefore improve ventilation. Once the initial monitoring is
completed, the monitor should then be carried by the entrant into the confined
space.
It is important to monitor at the top, middle and bottom of each
permit space. Some gases, such as methane, are lighter than air and will tend
to be present near the top of the space. Other gases, such as carbon
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monoxide, are the same density as air and will be found near the middle of
the confined space. Still other gases, like hydrogen sulphide, are much
heavier than air and will tend to be present near the bottom of the confined
space.
If testing reveals an oxygen deficiency or an oxygen-enriched atmosphere,
the presence of flammable gases or the presence of toxic gases or vapours,
the space must be ventilated and retested before workers may enter. If
ventilation is not possible and entry is necessary, for example in emergency
rescue, workers must have appropriate respiratory protection.
Hazards may exist at distances far from the entry point, and new hazards may
enter the system at any time. Continuous monitoring means that the person(s)
entering the confined space must carry the monitoring device with them into
the space. While the entrant is performing work in the space, the monitoring
device continues to look for changes in oxygen content or the presence of
flammable and/or toxic gases.
It is important to check the monitor before you enter the space to make sure
that the alarm is working properly. All monitors should have an alarm that can
be heard by the entrant or attendant above background noise levels. The
alarm sounds if the levels of oxygen, flammable gases or toxic gases are too
high or, in the case of oxygen, if the level is too low. Most monitoring devices
are also equipped with a visual alarm — a light that will flash rapidly at the
same time that the alarm goes off.
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Signposts and permits
All confined spaces should be clearly signposted. Safety regulations demand
that only workers with valid entry permits may go inside a confined space.
Those workers should be thoroughly trained and familiar with emergency
procedures.
Entry permit
The entry permit is the document that certifies that the employer complies with
the requirements of the standard for entries in permit-required confined
spaces. An entry permit must be filled out before a worker enters a confined
space (and posted at or near the confined space). It should contain the
following types of specific information concerning:
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Identification of space;
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Purpose of entry;
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Date and duration of permit;
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List of authorised entrants;
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Name of current Confined Space attendant/Safety Stand-By;
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The hazards of the permit space to be entered;
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The measures used to isolate the permit space and eliminate or
control hazards;
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The acceptable entry conditions;
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The results of atmospheric monitoring;
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Rescue and emergency services that can be summoned and the
means for summoning those services;
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The communication methods used by entrants and attendants to
maintain contact;
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Any other safety information necessary for the specific space; and/or
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Any additional permits, such as for “hot work” (welding).
Ventilation
The risks of confined spaces include low oxygen levels or harmful vapours. It
is impossible to smell oxygen or some lethal gases, so the human nose is an
unreliable indicator of safe or unsafe atmospheres. Instead, the air in confined
spaces needs to be regularly tested for oxygen and contaminants using the
proper equipment. Mechanical ventilation, such as fresh air blowers or
extractors, should always be used. Safety suggestions include:
•
Make sure any mechanical or other types of equipment are suitable,
especially equipment being used in flammable areas, which should
be non spark generating and flameproof.
•
Make sure the ventilation system is powerful enough to be effective.
•
Operate the ventilation system before anyone enters the confined
space to make sure the atmosphere is safe.
•
Ventilation should be operating continuously while anyone is inside
the confined space.
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The ventilation line should be close to the working face.
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Any exhaust from machinery should be vented straight out of the
confined space.
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When using vaporous chemicals such as solvents, refer to Material
Safety Data Sheets (MSDS) for their safe use.
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Air Monitoring equipment
If a safe atmosphere can’t be guaranteed, the use of appropriate safety
equipment, such as air-supplied respiratory protective equipment, is
paramount. If the confined space contains chemicals or dangerous
substances, other protective equipment required may include gloves, goggles
and overalls. It is also essential to have a GAS DETECTOR such as a Dräger,
to monitor oxygen levels and any other toxic gas levels inside the confined
space. Many monitors must be “calibrated” after every use in an environment
that has similar heat and humidity conditions as the confined space. The
manufacturer’s recommendations should be strictly followed. Many monitoring
devices must be “zeroed” OR “bumped” before each use by exposing the
monitor to clean air and setting the indicator to zero. Just turning the
instrument on is not enough. The indicator must be zeroed frequently in a
clean environment when monitoring an area for an extended period of time.
Harnesses and winches, when attached to the person entering the confined
space, are an excellent backup, but they must be properly organised.
Protective equipment
Personal protective equipment is used to protect workers only after all other
feasible means have been used to control or eliminate hazards. A full body or
chest harness and a lifeline should be used when entering a confined space.
In some situations, a respirator will also be needed. Air-purifying respirators
can filter dangerous substances from the air, but they provide no
protection in an oxygen deficient environment and should not be used
when working in a confined space. Only air-supplying respirators
(SAR/SCBA) should be used in confined spaces. An airline respirator can only
be used if the worker has a rescue bottle.
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Hardhats, safety goggles, face shields, gloves, safety shoes, boots,
disposable suits, ear plugs or muffs, non-sparking flashlight and tools may
also be needed when entering a confined space.
Observation and communication
Make sure the people inside the confined space are monitored from the
outside. There should be a person trained in initiating emergency procedures
observing them from a safe vantage point.
Standby person
The Standby Person must:
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Maintain visual and audible contact with those working in the Confined
Space.
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Maintain clear access/egress to Confined Space.
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Initiate emergency procedures where necessary.
•
Be responsible for administering the Confined Space Entry Permit.
•
Not enter the Confined Space unless he/she is relieved by another
standby person.
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Not participate in any other work duty or task while the Confined Space is
occupied.
If you are a confined space safety stand-by person, do not leave your post until you have
arranged and handed the confined space over to your replacement, giving all details, such
as who is inside and work being carried out, to your replacement.
If you are a confined space safety stand-by person, under no circumstances enter a
confined space if communication is lost with person inside or if an emergency occurs.
Follow the emergency procedures set out in the risk assessment/safe work method
statement and contact emergency services. Many people die trying to perform a rescue
themselves.
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Emergency procedures
When things go wrong, people may be exposed to serious and immediate
danger. Effective arrangements for raising the alarm and carrying out rescue
operations in an emergency are essential. Contingency plans will depend on
the nature of the confined space, the risks identified and consequently the
likely nature of an emergency rescue. Emergency arrangements will depend
on the risks. You should consider:
Communications
How can an emergency be communicated from inside the confined space
to people outside so that rescue procedures can start? Don’t forget night
and shift work, weekends and times when the premises are closed, eg
holidays. Also, consider what might happen and how the alarm can be
raised.
Rescue and resuscitation equipment
Provision of suitable rescue and resuscitation equipment will depend on the
likely emergencies identified. Where such equipment is provided for use by
rescuers, training in correct operation is essential.
Capabilities of rescuers
They need to be properly trained people, sufficiently fit to carry out their task,
ready at hand, and capable of using any equipment provided for rescue, eg
breathing apparatus, lifelines and firefighting equipment. Rescuers also need
to be protected against the cause of the emergency.
Shut down
It may be necessary to shut down adjacent plant before attempting
emergency rescue.
First aid procedures
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Trained first aiders need to be available to make proper use of any
necessary firstaid equipment provided.
Local emergency services
How are the local emergency services (eg, fire brigade) made aware of an
incident? What information about the particular dangers in the confined
space is given to them on their arrival?
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Contact WorkCover or your Union for advice and information.
REFERENCES
EXPOSURE STANDARDS FOR ATMOSPHERIC CONTAMINANTS IN THE OCCUPATIONAL ENVIRONMENT
SAFE WORKING IN A CONFINED SPACE - AUSTRALIAN STANDARD AS2865-1995 (NOHSC:1009(1994))
National Code of Practice for the Control of Workplace Hazardous Substances
This material was developed by Unions NSW with the assistance of The Workers
Health Centre as part of a project funded under the WorkCover NSW WorkCover
Assist Program.
Any views expressed are not necessarily those of WorkCover NSW.
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For more information please contact your union. This Fact Sheet is
recommended as a guide only and is not a substitute for professional or legal
advice. If you need clarification or further advice please consult your Union for
further information or
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