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Working in Confined Spaces

Published: 10th Oct 2002


The need to perform operations within Confined Spaces is a truly international problem. Each year millions of pounds are spent trying to remove the need to enter these spaces by changing processes, by designing out the spaces themselves and by the use of new technologies such as CCTV for inspection work.

However, in many instances the only way to achieve operational requirements is for manpower to enter spaces and carry out given tasks.

Irrespective of country or continent, all operations within these spaces are potentially dangerous due to the inherent risks, and world-wide many people are killed or seriously injured each year while working in them. A lack of control, lack of training, unsuitable equipment or a combination of these invariably causes these incidents. The consequences of an incident within a Confined Space can be very costly, not just in human terms, but as a result of prosecution, lost production and damage to plant and equipment.

Confined Spaces are found in one form or another in most industry sectors and each may have their own particular associated problems and risks, all of which must be fully assessed before an entry is made.

The need for Confined Space work gives rise to a wide variety of hazards that must be overcome to ensure the safety of the worker and in the worst case may lead to the need for a rescue to be carried out under the most difficult of circumstances. If there is no other option but to carry out work in these spaces we must first understand what they are and how we can best protect those who have to enter them.

So, what is a confined space?

In the United Kingdom this is defined as;

Any place including a chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or similar place in which by virtue of its enclosed nature there lies a reasonably foreseeable specified risk.

The UK definition of a Confined Space mentions ‘Specified Risks’ and these are categorised as follows for working in confined spaces:

  • Fires or explosions
  • Loss of consciousness due to an increase in body temperature
  • Loss of consciousness due to the increase of gases, vapours, fumes or the lack of Oxygen.
  • Drowning due to the increase in the level of liquid.
  • Axphyation or entrapment in a free flowing solid.

The use of these categories will assist in identifying any given risk and will help to identify if a space is indeed a Confined Space.

It must be remembered that the condition and construction of the Confined Space may only be part of the hazard. If the task to be performed within the space will in turn produce a hazard then this must also be considered. An example of this would be the fumes generated by welding or the vapour given off by solvents during painting or cleaning operations.

Control and Methods

The effective assessment and control of operations in these spaces is of paramount importance to ensure that the risks are minimised and that operators and workers can carry out tasks as safely as possible.

Internationally there is much ‘legislation’ and many ‘regulations’ and ‘guidelines’ that deal with operations in confined spaces. In this article we will consider the requirements of general industry. In certain industries such as Mining and Diving operations, specific legislation and methods will apply.

Safe Systems of Work

The fundamental methods and requirements for safe entry into a Confined Space are the same, whether the task is entry into an aircraft fuel tank, or into a sewer beneath a city street, in that, for operations to be carried out safely there must be some form of agreed and tested ‘Safe System of Work’.

A ‘Safe System of Work’ should take account of the specific risks involved and how to minimise these to make the task safe and without risk to health.

The ‘Safe System’ must also establish a workable hierarchy of those who are to be involved in ‘Confined Space’ operations from management through operators with roles and responsibilities accurately defined.

Factors that should be considered in the design of a Safe System of Work should include:

  • Adequate supervision
  • Competence and training of the operatives
  • Communications
  • Testing and monitoring of the atmosphere
  • Purging and ventilation
  • Removal of residue
  • Isolation of gases, liquids and other flowing materials
  • Isolation of mechanical and electrical equipment and services
  • Selection and use of suitable equipment
  • PPE (Personal protective equipment)
  • RPE (Respiratory protective equipment)
  • The safe use of portable gas cylinders and internal combustion engines
  • Gas supplied from pipes and hoses
  • Access and egress
  • Fire prevention
  • Lighting
  • Static electricity
  • Smoking policy
  • Limited working times
  • Emergency and rescue procedures

Risk Assessment

To ensure that all risks have been identified the Safe System Of Work must include a formal ‘Risk Assessment’ used to establish the risks present in a given space and for the operations to be carried out within that space. The assessment will need to identify the risks not only to those entering and working within the space but also to other persons in the immediate vicinity such as the general public.

There are generally five steps to an effective Risk Assessment:

  • Identify the hazards involved
  • Identify who is at risk from the hazards
  • Evaluate the risks and decide whether the existing precautions are adequate or whether more precautions need to be taken
  • Record the details and findings of the assessment
  • Review the assessment as necessary

To ensure that the Risk Assessment has been completed correctly and that all risks have been fully assessed and documented a ‘Permit to Work’ may be used before any entry is made.


In addition to ensuring that the area is as safe as possible for those entering, the Safe System of Work must also identify the actions and procedures to be adopted should there be an accident or incident within the space.

The rescue of an individual or individuals from a Confined Space may present some unique problems and challenges to the rescue services and these must be fully considered and accounted for. Specialist rescue equipment and methods may need to be employed and those responsible for performing a rescue will need to be fully aware of the risks as well as any local difficulties of access so that they may equip and train themselves for any eventuality.

If Fire and Rescue Services are available locally, then they should be fully involved in the Risk Assessment process. If however the system is reliant on an external Fire and Rescue agency, provision must be made for their involvement and effective communications made about the nature of the confined space and the work to be undertaken. In many cases the apparatus and equipment carried by the local Fire Service will be ill suited to the rescue of people from a confined space.

Consider the following when making arrangements for a rescue:

  • Rescue and resuscitation equipment
  • Raising the alarm
  • Safeguarding the rescuers
  • Fire / chemical safety
  • Control of plant and machinery
  • First aid
  • Public emergency services
  • Training


To allow for safe working in Confined Spaces, operators will need to be equipped with the correct equipment to ensure that their safety is not compromised, in addition to that required for the task at hand.

The equipment required will depend on the exact nature of the confined space and the hazards that may be encountered which will have been determined by the use of a ‘Risk Assessment’ as part of a ‘Safe System of Work’ as previously described.

Internationally there is a vast selection of equipment that may be suitable for use in a confined space. The continuing development of the ‘World Wide Web’ allows purchasers and specifiers to receive information from all corners of the globe and to gather information on a huge range of products. To avoid some of the possible pitfalls in selecting the correct equipment the following points should be considered:

  • Approval of the equipment in the country/region where it is to be used
  • Suitability of the equipment for the task at hand
  • Compatibility of the equipment with other items in use
  • Complete and comprehensive training for all equipment users
  • Local support and maintenance for the chosen equipment
  • Control and upkeep of equipment within the work place

The following is a representative but not exhaustive list of some of the equipment that may be required together with a brief explanation of why it has been included.


Allows for the safe entry and egress of workers and to recover casualties in the event of an emergency.

Fall Arrest Device

To limit the dangers when descending down ladders or foot irons.


To allow for the safe and effective lowering and lifting of workers (be they conscious or unconscious). It must be stressed that the design of harnesses varies greatly and for confined space operations a harness is needed that can be used for the raising and lowering of a worker or an unconscious casualty or for connection to a Fall Arrest device if this is to be used.


To allow for the recovery of a casualty and also to ensure that ‘contact’ is maintained between team members.

Gas Detectors/Monitors

To allow for the testing of the atmosphere within a confined space from a safe distance prior to entry and to allow for continuous monitoring of the atmosphere while the space is occupied. To be effective, the gas monitoring equipment must be relevant to the expected contaminants.

Forced Venting/Extraction

Facilitates the effective ‘purging’ of a confined space to ensure that there is a safe atmosphere before entry and during operations.

Lighting and other Electrical Equipment

All lighting and other electrical equipment used within a confined space must be rated and approved as ‘explosion proof ’.

Respiratory Protective Equipment (RPE)

The risk assessment will identify if it is necessary to provide RPE for those entering the space. The suitability of any RPE must be confirmed against the likely risks that may be present. For example, it would be pointless to supply a filter mask to an operative who may encounter an oxygen deficient atmosphere!

The four types of RPE available are:

  • Filter masks
  • Oxygen rebreathers
  • Self contained compressed air breathing apparatus
  • Air-line breathing apparatus

In addition to the apparatus type selected, consideration must be given to the effective working duration of the RPE such that sufficient protection is given in an emergency.

The provision of suitable RPE must also be considered for any ‘rescue’ activities.

For example, the use of a full duration SCBA (self-contained breathing apparatus) may not be suitable if any rescue attempt will have to be made via a small opening into the space.

Personnel Protective Equipment (PPE)

Some form of PPE will invariably be required when working within a Confined Space. The nature of protection and items required will depend on the risks identified and the nature of the space. The following should be considered:

  • Head protection
  • Safety footwear
  • Gloves
  • Coveralls / overalls
  • Hearing protection
  • Eye protection
  • Specialist items such as waders, wet suits, etc

Signs, Locks and Tallies

To ensure that all processes, supplies and services that may affect the space are suitably isolated and ‘locked off ’ before and during entry.


To allow for the safe working of operators some form of communication will be required between those involved. The method of communication chosen will depend on the nature of the task but may be:

  • Rope/line pulls
  • Verbal
  • Horns
  • Whistles
  • Radios (approved for use in confined spaces)
  • Hand claps

The method chosen must be suitable. For example, the use of whistles will not be effective if the operators are wearing breathing apparatus!

Resuscitation Equipment

The risk assessment may highlight the need for suitable resuscitation equipment to be available during operations.


The very nature of working in Confined Spaces together with the need for a wide range of complex equipment and procedures requires that all persons involved be fully trained to the highest level.

Those involved in the management of operations must have a full understanding of the risks involved and the content and operation of the Safe System of Work, while operators must be fully conversant with the systems together with a high level of competence and confidence in the use of all equipment and methods to be employed.

While theoretical training may go some way to providing the necessary knowledge, there can be no substitute for practical training using all of the methods and equipment provided. To ensure competence and full understanding, any training should include both practical and theoretical examinations. Only after complete training should individuals be tasked with carrying out operations in Confined Spaces.

Personnel and Team Structure

Any entry into a confined space will require manpower. The ‘given task’ to be performed within the space may be very simple e.g. closing a valve, but if this valve is a long distance from the point of entry and there are several bulkheads or baffles in the way then several people will be required to ensure the safety of the man turning the valve.

Every member of this team will have a role and responsibility to himself and the others in his team. Each team member must fully understand their role and responsibilities as well as the full details of the task at hand. Probably the most important team role is that of the ‘Top Man’ or ‘Entry Controller’. This individual is responsible for:

  • Ensuring the safety of all those inside the confined space
  • Ensuring that all equipment and apparatus are used correctly
  • Ensuring that communications are maintained within the team
  • Summoning assistance from the emergency services if required
  • Co-ordinating activities to a satisfactory conclusion

In addition to understanding the team structure, all team members will need to be ‘suitable’ to work in confined spaces. Due to the nature of the task, individuals selected for work in Confined Spaces will need to meet certain criteria.

  • General level of fitness – work may be very physical
  • Physical size – considering entry through a tight access/egress point
  • Mental state – someone suffering from Claustrophobia will be unsuitable
  • Training – all operators must be fully trained
  • Suitable for the task – the entrant must be capable of performing the given task once entry has been made


This brief article cannot hope to give all of the answers to working safely in confined spaces. Indeed it has only scratched the surface of what is a complicated and diverse issue. It should, however, have conveyed the message that a ‘Safe System of Work’, combined with well-selected equipment and fully trained personnel will minimise the chances of any incident being encountered while working in Confined Spaces.

Published: 10th Oct 2002 in Health and Safety International

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