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Every year workers die in confined spaces. These deaths typically occur for two reasons:

  1. Employers and workers fail to recognize and control the hazards associated with confined spaces, and
  2. Inadequate or incorrect emergency response results in the death of the initial entrant, the would-be rescuer, or both.

Atmospheric hazards and physical hazards may be present in confined spaces. Atmospheric hazards include oxygen deficiency or enrichment, flammable atmospheres, and toxic air contaminants. Examples of physical hazards include moving parts in mechanical systems, release of stored energy in hydraulic or pneumatic lines, electrical energy, engulfment by loose materials, and drowning.

A confined space is a space with all of the following characteristics:

*       It is large enough that a person can enter and perform the assigned work.

*       The means of entry or exit are limited or restricted.

*       It is not designed for continuous human occupancy.

Tanks, pits, silos, and sewers are just a few examples of confined spaces.

A permit-required confined space is a confined space with one or more of the following characteristics:

*       It contains or has the potential to contain a hazardous atmosphere (i.e., an atmosphere that may expose employees to the risk of injury or death, ability to self-rescue, or acute illness).

*       It contains a material that has the potential for engulfing an entrant.

*       An entrant could become trapped or asphyxiated by inwardly converging walls or a floor that slopes downward and tapers to a smaller cross section.

*       It contains any other recognized serious safety or health hazard.

Employers must evaluate the workplace to determine if there are any permit-required confined spaces (or permit spaces) within the workplace. Employers must inform employees of the existence of any permit spaces through signs or other equally effective means and prevent unauthorized entry.

A permit system and a written permit-required confined space program must be developed if employees are to enter permit spaces. The permit system, which authorizes entry into a permit space, must include:

       Identification of the space.

       Purpose of the entry.

       Date and duration of the permit.

       Names of authorized entrants within the space, current attendants, and current entry supervisor.

       Hazards of the permit space.

       Measures to isolate the space and eliminate or control hazards.

       Acceptable entry conditions.

       Results of initial and periodic atmospheric testing.

       Onsite rescue and emergency services and additional services that can be summoned.

       Communication procedures between entrants and attendants.

       Equipment provided, such as PPE, testing equipment, communications equipment, alarm systems, and rescue equipment.

       Any other necessary information to ensure employee safety.

       Any additional permits, such as for hot work.

The permit must be signed by the entry supervisor to authorize entry. The permit is made available to all entrants prior to entry by posting at the entry portal or other means. The permit is canceled when the task is completed or when unacceptable conditions arise.

Authorized entrants must properly use any required equipment and communicate with the attendant during entry. The entrants must alert the attendant and exit as quickly as possible when there are any signs or symptoms of a dangerous condition or when a prohibited condition exists. They must also exit as quickly as possible when ordered to by the entry supervisor or attendant.

An attendant is required to monitor entrant status along with activities inside and outside the space. There must be an attendant outside the space at all times during the entry. The attendant takes action to prevent unauthorized entry; orders evacuation of the space if necessary, summons rescuers, and performs non-entry rescues or other rescue services as part of the employer’s on-site rescue procedure.

Entry supervisors review the permit to ensure that all tests have been conducted and all procedures and equipment are in place before signing the permit. They also terminate entry and cancel permits, verify that rescue services are available and that the means for summoning additional services are operable, remove unauthorized individuals who enter the space, and determine that acceptable conditions continue when entry supervisors or shifts change and as needed.

Rescue and emergency services must be provided. At least one standby person must be immediately available at the site to perform rescue and emergency services. This standby person must be able to perform both non-entry and entry rescue as needed. The employer may also arrange for additional, offsite rescue services to be summoned. To facilitate non-entry rescue, retrieval systems must be used during all entries unless such equipment would increase the overall risk of entry or would not aid in rescue.

Training must be provided to ensure that entrants, attendants, and entry supervisors know the hazards that may be faced during entry and that they are proficient in their duties. In addition to initial training, refresher training is conducted as needed. The employer must certify that the training has occurred.

Members of the rescue service must receive the same training required by entrants plus additional training. They must also practice simulated permit space rescues from the actual permit spaces or comparable spaces at least every 12 months. Outside rescue services must be made aware of hazards and receive access to all permit spaces so they can develop rescue plans and practice rescues operations.

Alternate procedures can be used for entering permit spaces where the only hazards are atmospheric and ventilation alone can control the hazards. To qualify for alternate procedures, certain conditions must be met and certain procedures must be followed. The use of alternate procedures eliminates the need for a permit system, attendants, an entry supervisor, and rescue and emergency services.

A permit space may be reclassified as a non-permit space if the permit space poses no actual or potential atmospheric hazards and if all hazards with the space are eliminated. If entry must be made to eliminate the hazards, this entry must be done using the permit system. The elimination of hazards must be documented and certified by the employer. The space may be reclassified only for as long as the hazards remain eliminated.

If contractors are hired to enter a space, the host employer must inform the contractor of the hazards of the space and that a permit-required confined space program is required for entry into the space. The contractor must be debriefed at the conclusion of entry operations. Joint entries must be coordinated.

Safe Work In Confined Spaces Can Be Deadly

Confined space can be deadly

A number of people are killed or seriously injured in confined spaces each year. This happens in a wide range of industries, from those involving complex plant to simple storage vessels. Those killed include not only people working in the confined space but those who try to rescue them without proper training and equipment.

What is a confined space?

It can be any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions (eg lack of oxygen). Some confined spaces are fairly easy to identify, eg enclosures with limited openings:

  • storage tanks;
  •  silos;
  •  reaction vessels;
  •  enclosed drains;
  •  Sewers.

 

Others may be less obvious, but can be equally dangerous, for example:

  •  open-topped chambers;
  •  vats;
  •  combustion chambers in furnaces etc;
  •  ductwork;
  •  Unventilated or poorly ventilated rooms.

 

It is not possible to provide a comprehensive list of confined spaces. Some places may become confined spaces when work is carried out, or during their construction, fabrication or subsequent modification.

 

What are the dangers from confined spaces?

Dangers can arise in confined spaces because of:

► A lack of oxygen.

This can occur:

- where there is a reaction between some soils and the oxygen in the atmosphere;

- following the action of groundwater on chalk and limestone which can produce carbon dioxide and displace normal air;

- in ships’ holds, freight containers, lorries etc as a result of the cargo reacting with oxygen inside the space;

- inside steel tanks and vessels when rust forms.

► Poisonous gas, fume or vapour.

These can:

- build-up in sewers and manholes and in pits connected to the system;

- enter tanks or vessels from connecting pipes;

- leak into trenches and pits in contaminated land, such as old refuse tips and

old gas works.

► Liquids and solids which can suddenly fill the space, or release gases into it, when disturbed. Free flowing solids such as grain can also partially solidify or ‘bridge’ in silos causing blockages which can collapse unexpectedly.

► Fire and explosions (eg from flammable vapours, excess oxygen etc).

► Residues left in tanks, vessels etc, or remaining on internal surfaces which can give off gas, fume or vapour.

► Dust may be present in high concentrations, eg in flour silos.

► Hot conditions leading to a dangerous increase in body temperature. Some of the above conditions may already be present in the confined space. However, some may arise through the work being carried out, or because of ineffective isolation of plant nearby, eg leakage from a pipe connected to the confined space. The enclosure and working space may increase other dangers arising through the work being carried out, for example:

► Machinery being used may require special precautions, such as provision of dust extraction for a portable grinder, or special precautions against electric shock;

► gas, fume or vapour can arise from welding, or by use of volatile and often flammable solvents, adhesives etc;

► if access to the space is through a restricted entrance, such as a manhole, escape or rescue in an emergency will be more difficult

What the law says

You must carry out a suitable and sufficient assessment of the risks for all work activities for the purpose of deciding what measures are necessary for safety (The Management of Health and Safety at Work Regulations 1999, regulation 3). For work in confined spaces this means identifying the hazards present, assessing the risks and determining what precautions to take. In most cases the assessment will include consideration of:

► the task;

► the working environment;

► working materials and tools;

► the suitability of those carrying out the task;

► arrangements for emergency rescue.

 

HSE’s free leaflet Five steps to risk assessment will help you further. You may need to appoint competent people to help manage the risks and ensure that employees are adequately trained and instructed (The Management of Health and Safety at Work Regulations 1999, regulation 7). Of course, you may be the best person to do this, however, you may need to train someone else or engage the services of a competent person for additional help. If your assessment identifies risks of serious injury from work in confined spaces, such as the dangers highlighted above, the Confined Spaces Regulations 1997 apply. These regulations contain the following key duties:

► avoid entry to confined spaces, eg by doing the work from outside;

► if entry to a confined space is unavoidable, follow a safe system of work; and

► put in place adequate emergency arrangements before the work starts.

These duties, and what you need to do, are further described in this document.

Avoid entering confined spaces

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;

► have the work 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.

Safe systems of work

If you cannot avoid entry into a confined space make sure you have a safe system for working inside the space. Use the results of your risk assessment to help identify the necessary precautions to reduce the risk of injury. These will depend on the nature of the confined space, the associated risk and the work involved. Make sure that the safe system of work, including the precautions identified, is developed and put into practice. Everyone involved will need to be properly trained and instructed to make sure they know what to do and how to do it safely. The following checklist is not intended to be exhaustive but includes many of the essential elements to help prepare a safe system of work.

Appointment of a supervisor

Supervisors should be given responsibility to ensure that the necessary precautions are taken, to check safety at each stage and may need to remain present while work is underway.

 

Are persons suitable for the work?

Do they have sufficient experience of the type of work to be carried out, and what training have they received? Where risk assessment highlights exceptional constraints as a result of the physical layout, are individuals of suitable build? The competent person may need to consider other factors, eg concerning claustrophobia or fitness to wear breathing apparatus, and medical advice on an individual’s suitability may be needed.

Isolation

Mechanical and electrical isolation of equipment is essential if it could otherwise operate, or be operated, inadvertently. If gas, fume or vapour could enter the confined space, physical isolation of pipework etc needs to be made. In all cases a check should be made to ensure isolation is effective.

Cleaning before entry

This may be necessary to ensure fumes do not develop from residues etc while the work is being done.

Check the size of the entrance

Is it big enough to allow workers wearing all the necessary equipment to climb in and out easily, and provide ready access and egress in an emergency? For example, the size of the opening may mean choosing air-line breathing apparatus in place of self-contained equipment which is more bulky and therefore likely to restrict ready passage.

Provision of ventilation

You may be able to increase the number of openings and therefore improve ventilation. Mechanical ventilation may be necessary to ensure an adequate supply of fresh air. This is essential where portable gas cylinders and diesel-fuelled equipment are used inside the space because of the dangers from build-up of engine exhaust. Warning: carbon monoxide in the exhaust from petrol-fuelled engines is so dangerous that use of such equipment in confined spaces should never be allowed.

Testing the air

This may be necessary to check that it is free from both toxic and flammable vapours and that it is fit to breathe. Testing should be carried out by a competent person using a suitable gas detector which is correctly calibrated. Where the risk assessment indicates that conditions may change, or as a further precaution, continuous monitoring of the air may be necessary.

Provision of special tools and lighting

Non-sparking tools and specially protected lighting are essential where flammable or potentially explosive atmospheres are likely. In certain confined spaces (eg inside metal tanks) suitable precautions to prevent electric shock include use of extra low voltage equipment (typically less than 25 V) and, where necessary, residual current devices.

 

Provision of breathing apparatus

This is essential if the air inside the space cannot be made fit to breathe because of gas, fume or vapour present, or lack of oxygen. Never try to ‘sweeten’ the air in a confined space with oxygen as this can greatly increase the risk of a fire or explosion.

Preparation of emergency arrangements

This will need to cover the necessary equipment, training and practice drills.

Provision of rescue harnesses

Lifelines attached to harnesses should run back to a point outside the confined space.

Communications

An adequate communications system is needed to enable communication between people inside and outside the confined space and to summon help in an emergency.

Check how the alarm is raised

Is it necessary to station someone outside to keep watch and to communicate with anyone inside, raise the alarm quickly in an emergency, and take charge of the rescue procedures?

Is a ‘permit-to-work’ necessary?

A permit-to-work ensures a formal check is undertaken to ensure all the elements of a safe system of work are in place before people are allowed to enter or work in the confined space. It is also a means of communication between site management, supervisors, and those carrying out the hazardous work. Essential features of a permit-to-work are:

► clear identification of who may authorise particular jobs (and any limits to their authority) and who is responsible for specifying the necessary precautions (eg isolation, air testing, emergency arrangements etc);

► provision for ensuring that contractors engaged to carry out work are included;

► training and instruction in the issue of permits;

► monitoring and auditing to ensure that the system works as intended.

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 fire-fighting 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

Trained first aiders need to be available to make proper use of any necessary firstaid equipment provided.