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Potential hazards in confined spaces come in many forms, including atmospheric, physical, chemical, process, and human hazards.
Confined spaces pose dangers because they are usually not designed to be areas where people work. Confined spaces often have poor ventilation and this allows hazardous atmospheres to quickly develop, especially if the space is small. The hazards are not always obvious and may change from one entry into the confined space to the next.
The risks of working in confined spaces include:
• Loss of consciousness, injury or death due to the immediate effects of airborne contaminants
• Fire or explosion from the ignition of flammable contaminants
• Difficulty rescuing and treating an injured or unconscious person
• Asphyxiation resulting from oxygen deficiency or immersion in free-flowing materials such as liquids, grain, sand, or fertiliser
In addition, the confined space is or is likely to be a risk to health and safety from:
• An atmosphere that does not have a safe oxygen level
• Contaminants, including airborne gases, vapours and dusts, that may cause injury from fire or explosion
• Harmful concentrations of any airborne contaminants
A confined space is determined by the hazards associated with a set of specific circumstances; not just because work is performed in a small space. Confined spaces are commonly found in vats, tanks, pits, pipes, ducts, flues, chimneys, silos, containers, pressure vessels, underground sewers, wet or dry wells, shafts, trenches, tunnels or other similar enclosed or partially enclosed structures, when these examples meet the definition of a confined space in your relevant country’s regulations.
Entry into a confined space means any situation in which any part of the body of any person is located within the space regardless of the length of time taken. This can also take into consideration the depth of exposure versus the height of the worker where there is direct or indirect exposure to an unknown substance such as a contaminated gas, which may affect the health of a worker.
If it is not reasonably practicable to eliminate the need to enter the confined space or the risk of inadvertent entry, then any risk associated with entry to and exit from the space must be minimised. Entry and exit of a confined space is safer when openings (access points) are large and located in a position that allows for persons and equipment to pass easily through them.
Where relevant, the following features should be incorporated at the design, manufacture and installation stages:
1. Access points (including those within the confined space, through divisions, partitions or obstructions) should be large enough to allow people wearing the necessary protective clothing and equipment to pass through, and to permit the rescue of all people who may enter the confined space.
2. A safe means of access to and within the confined space, such as fixed ladders, platforms and walkways should be provided. Further guidance is available in AS 1657 Fixed platforms, walkways, stairways and ladders – design, construction and installation.
3. Access points should not be obstructed by fittings or equipment that could impede rescue and should also be kept free of any obstructions during work in the confined space. If equipment such as electrical cables, leads, hoses and ventilation ducts are required to pass through an access hole, a second access point may be needed.
4. There should be enough access points to provide safe entry to and exit from the confined space. For example, the spacing of access holes on sewers (or in the case of large gas mains, the absence of such access holes over considerable lengths) may affect both the degree of natural ventilation and the ease with which persons can be rescued.
In order to manage risk, as far as is reasonably practicable a duty holder must:
• Identify foreseeable hazards that could give rise to the risk
• Eliminate the risk
• If elimination is not possible, minimise the risk by implementing control measures in accordance with the hierarchy of control
• Maintain the implemented control measure so that it remains effective
• Review, and if necessary revise, risk control measures so as to maintain a work environment that is without risks to health and safety
This guidance on how to manage the risks associated with a confined space is based on following a systematic process, which involves:
• Identifying hazards associated with confined spaces
• Assessing the risks associated with these hazards
• Implementing risk control measures
• Reviewing risk control measures
Duties in relation to confined spaces include:
• Managing health and safety risks associated with a confined space, including risks when entering, working in, on or near a confined space, as well as the risk of inadvertent entry
• Ensuring, so far as is reasonably practicable, that a worker does not enter a confined space until all the duties in relation to the confined space have been complied with, for example entry permit requirements
• Establishing first aid and rescue procedures to be followed in the event of an emergency in the confined space
Wherever practicable, the need for people to enter the confined space must be eliminated.
Where the fire rating has been declared as extreme or above, under these conditions it is possible that emergency services may not have available resources to assist in the event of an emergency and, unless the activity is for the purpose of prevention of public health risk, works should be postponed.
If this is not practicable, it is a requirement that the risks of the task are identified, assessed and appropriate controls put in place as early as possible before any work commences. Controls may include engineering controls, administration and/or protective equipment or a combination of controls.
The work crew, in conjunction with other relevant people and/or specialist advice as identified, must complete the risk assessment prior to entry as required.
The risk assessment must cover the full scope of works planned plus any potential rescue operation. While planning any rescue operation thought must be given to the location of the entry (i.e. remote location) and the time for any emergency assistance to arrive.
The risk assessment must also identify other precautions required due to the type of space, its layout, the surrounding environment and any other factors. Identifying these factors is important as other permits, training requirements or equipment may be required prior to entry and will vary from site to site. Examples of other factors may include:
• Fall from heights requirements
• Hot works or chemical usage
• Potential ignition (such as lighting or electrical tools)
• Contaminant sources
• Atmospheric conditions
If at any point during the work conditions change, the risk assessment must be revisited by the work party and modified if required.
The risk assessment must be available prior to, during and after completion of any or all entries and work in the confined space.
Generic risk assessments may be used for repeated tasks or entries into similar spaces. It is the responsibility of the person in charge performing the entry to show that the risk assessment is relevant to the space being entered.
A documented assessment of all hazards associated with the work, the risk levels and the controls required to ensure work can be performed safely. When undertaking a risk assessment to determine the risks requiring control, the assessment will need to consider the following in most cases:
• The hazards identified
• The task
• The working environment
• Work materials and tools
• All permits associated with the work
• The additional physiological and psychological demands of the task
• Arrangements for emergency rescue
• Training requirements
Safe oxygen level
An atmosphere containing not less than 19.5% and not more than 23.5% oxygen.
Person in charge of the entry
The person responsible for the overall supervision of the work being conducted within the confined space.
A person who has the responsibility for assisting the person/s entering or exiting the confined space must complete the work permits to ensure all persons and equipment have exited the confined space and instigate emergency response from outside the confined space.
Personnel within the immediate vicinity (sight and sound) who will make initial contact with emergency services if required and provide initial emergency rescue response from outside the confined space.
Standard gas detectors
Standard electronic gas detection meters must be approved and be capable of testing for the four standard gases as listed in Table 1.
Pre-entry testing must occur before each and every entry (refer definition) into the confined space. Results must be recorded on the CSE Permit.
Pre-entry testing must be conducted for oxygen, carbon monoxide, hydrogen sulphide and explosive-gas levels.
The measurement of atmospheric, explosive and relevant hazardous gas concentration levels must be undertaken and interpreted by appropriately trained persons.
If pre-entry testing shows non-compliance with any of the required levels, the space must not be entered. Appropriate options to improve the atmospheric conditions must be implemented and compliance with acceptable entry limits must be achieved before entry is permitted.
If explosive gases are found to be present at concentrations greater than 5% of their LEL after 10 minutes, all opened entries should be closed and the job location reported to the relevant supervisor immediately. Continuous monitoring is required for all confined space entries.
If the entry party is required to exit the space as a result of the gas detector alarming, the space must be re-assessed prior to any re-entry to ensure conditions are returned to acceptable levels.
In some confined spaces it will be necessary to monitor for atmospheric contaminants in addition to those listed above.
This may be because the atmosphere may be affected by:
• Non-compliant industrial discharges, particularly sewerage assets
• Tasks being performed by other persons around the space
• Observation of abnormal conditions by the work crew
• Spillages or discharges into drains
• The task performed requiring the use of materials containing volatile solvents
Consideration must be given to:
1. The location of the confined space – the geographic location of the space, its accessibility in an emergency and the distance to appropriate medical facilities all need to be taken into account.
2. Communications – How can people working inside the space communicate to people outside in an emergency? Exactly how will the alarm be raised and by whom? Planning needs to ensure that rescue and emergency personnel can access the workplace during night shifts, weekends and holiday periods.
3. Rescue and resuscitation equipment – the provision of suitable rescue and resuscitation equipment will depend on the potential emergencies identified. Training in the correct operation of rescue equipment is essential where such equipment is provided. Selected rescue equipment needs to be in close proximity to the confined space and able to be used immediately.
4. Capabilities of rescuers – rescuers need to be properly trained, sufficiently fit to carry out their task and capable of using any equipment provided for rescue (e.g. breathing apparatus, lifelines and fire-fighting equipment). Rescuers also need to be protected against the cause of the emergency.
5. First aid procedures – trained first aiders need to be available to make proper use of any necessary first aid equipment provided.
6. Local emergency services – if local emergency services are to be relied upon for rescue:
a. How will they be notified of an incident?
b. What information about the particular dangers in the confined space will be given to them on their arrival?
c. Have prior arrangements been made with local emergency services to ensure they are able to respond in a reasonable time, and have the specialist confined space retrieval equipment readily available?
d. Rehearsal – the emergency procedures must be rehearsed with relevant employees to demonstrate that the specific rescue plan for the space is effective.
Continuous communication must be maintained between those on the surface and those below. As far as is practical communication must be maintained onsite at all times.
Radio or telephone communication must be available at all times onsite to enable contact with the relevant control room and/or emergency services.
Communication between the surface and those below can be maintained by using a combination of the following:
• Torch signals
• Air horn
• Approved radio communication equipment (intrinsically safe)
• Signals on the safety line: one tug to stop when in motion; two tugs to lower; three or more tugs to attract attention
Some examples of when distress signals may be generated by the party below include: person feeling ill, person injuring themselves while working in the confined space.
The method of communication must be established in the risk assessment prior to entry.
As will be detailed in the following sections, other safety considerations include: maintenance of plant and equipment; ignition sources; the use of protective equipment; and entering the space.
Wear protective headwear as required when working in confined spaces. This is for protection from objects being lowered or accidentally dropped from above, and to protect you from bumping your head in confined areas.
The surface crew must wear safety helmets when loads are being carried above them, e.g. when equipment is being lowered into an access pit by crane.
Bump caps may be worn in areas such as smaller diameter sewers, drains or pipes if there is no risk of objects falling from above. No equipment is to be raised or lowered directly above persons wearing bump caps.
The selection of the appropriate protective clothing to be worn within a confined space depends both upon the type of confined space and the work being performed.
The risk assessment prepared for the work being performed must identify the specific protective clothing requirements for the task.
Contaminated clothing or equipment must never be taken home. All contaminated clothing should be appropriately disposed of, or arrangements must be made to launder contaminated clothing through any local workplace laundering arrangements.
In addition to wearing head protection and protective clothing, the standby person should control the safety line while people are working below and connected to the safety line. The safety line may be controlled manually or mechanically. Mechanical control is preferred as far as is practical.
If a safety line is used and there is potential for the safety line to tangle in equipment while working in the space then the safety line may be disconnected, but must remain at the base of the access ladder and reconnected before ascent out of the confined space.
If the need to disconnect from the safety line occurs while within the confined space, the risk assessment must be revised to take into account the potential for different hazards and different types of rescue that may be required.
Entering the space
If the surface opening is larger than 300mm x 300mm the risk of a fall must be assessed and controls identified.
Control measures that have been implemented must be reviewed and if necessary revised to make sure they work as planned and to maintain, so far as is reasonably practicable, a work environment that is without risks to health and safety.
A person conducting a business or undertaking must review and as necessary revise risk control measures:
• When the control measure does not minimise the risk so far as is reasonably practicable
• Before a change at the workplace that is likely to give rise to a new or different health and safety risk that the control measure may not effectively control
• If a new hazard or risk is identified
• If the results of consultation indicate that a review is necessary
• If a health and safety representative requests a review
Control measures may be reviewed using the same methods as the initial hazard identification step.
In undertaking the review, consult workers involved in the confined space work and their health and safety representatives and consider the following questions:
• Are the control measures working effectively in both their design and operation?
• How effective is the risk assessment process? Are all hazards being identified?
• Are workers actively involved in the risk management process? Are they openly raising health and safety concerns and reporting problems promptly?
• Have new work methods or new equipment made the job safer?
• Are safety procedures being followed?
• Has instruction and training provided to workers been successful?
• If new legislation or new information becomes available, does it indicate current controls may no longer be the most effective?
• Is any change planned to any plant or structure that may create a confined space or change the nature of an existing confined space?
• Has an incident occurred as a result of work carried out in a confined space?
If problems are found, go back to any point in the risk management process, review the information and revise any decisions about controls measures.
Published: 2nd Mar 2016 in Health and Safety Middle East
Mark Da Silva
Mark Da Silva is Director of Work, Health and Safety Programmes at WorkSafe Victoria. As the Director of Programmes his remit includes leading and facilitating the delivery of the strategic health and safety improvement programmes; aimed at reducing injury, illness and fatalities in Victoria workplaces.
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