Confined Space

NEBOSH Certificate: 1.3.10

PAUL RANDALL AND ASSOCIATESHealth and safety Training

CONFINED SPACESCONFINED SPACESCONFINED SPACESCONFINED SPACESCONFINED SPACES

Confined spaces

1 Confined spaces, an introduction ...................................................... 5

2 The Confined Spaces Regulations 1997 .......................................... 72.1 Avoiding entry into confined spaces ......................................... 82.2 Safe system of work ................................................................. 82.3 Emergency procedures ........................................................... 10

3 Typical confined space problems .................................................... 103.1 Hazards presented by gases, fumes and vapours ................. 103.2 Oxygen deficiency ................................................................... 113.3 Fire, explosion and other hazards .......................................... 12

4 Reducing confined space hazaards ................................................ 12

Syllabus coverage 1.3.10 The main hazards and safe working practices associated with

confined spaces; the measures necessary to comply with TheConfined Spaces Regulations 1997

Required reading Safe work in confined spaces, INDG 258, HSE Books 1998

Confined spaces

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Confined spaces


1 Confined spaces, an introductionThose of you who use a word processor are probably used to thespell checker blissfully displaying its ignorance of matters scien-tific - mine recently confidently suggested that I should changeearthing (in a book on electrical safety) to earthling.When checking an early draft of the present text the spell checkerwanted to know if I wished to replace confined space withconfused space (whatever that is). No thanks, I didnt, but it setme thinking that the spell checker had for once hit a nail on thehead - one crucial aspect of a confined space being the uncer-tainty as to just what conditions will be encountered.A formal definition of a confined space would include the words ...

... any enclosed environment ... liable to present hazards tohuman health ... as a result of presence of hazardoussubstances ... or absence of oxygen ... excessive conditions oftemperature or pressure ... fire and explosion ...

Examples of confined spaces include: drains and culverts inside the segments of a box-girder bridge ventilation ducting food storage facilities plant rooms compartments of a ship... no doubt you could add many more examples to this list.Just some examples of confined space fatalities (there are about20 per year) include: a devastating fire in a ships compartment in which the air had

been sweetened with oxygen; poor communications betweenmanagement and two groups of workers led to inappropriateuse of welding equipment - 8 men died

a lone worker fell into a grain silo and suffocated; no onemissed him, his body was discovered two days later

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a faulty waste disposal system on a ship led to the fumes fromdecomposing waste matter killing two children in their bunks

two council workmen died when they were overcome by fumesfrom toxic chemicals when cleaning a sewage system

a worker cleaning out a storage tank was overcome by thevapour from the solvent he was using; he collapsed with aheart attack and died

a massive explosion in an underground water pumping stationwas caused when a build-up of methane gas was ignited.

a welder was killed when the residues in the storage tankwhich he was repairing, exploded

a relatively small quantity of fuel oil leaking into buildingexcavations resulted in a fatal fire

Looking through these examples you will perhaps see a patternbeginning to emerge, combinations of circumstances and behav-iour leading to tragedy. The key legislation designed to preventsuch tragedies is The Confined Spaces Regulations 1997, whichwe will discuss shortly.The legal foundation for the 1997 Regulations are to be found inearlier legislation, including:

The Health and Safety at Work etc Act 1974; section 2 of thisAct (to which we will fequently return) requires employers toprotect employees against risks to safety and health, and toprovide safe systems of work etc. Implicitly, this will coverconfined spaces although they are not mentioned as such.The COSHH Regulations deal with the prevention and controlof exposure to hazardous substances in any work environmentincluding, obviously, confined spaces.The Management of Health and Safety at Work Regulations1999 require that the employer undertakes an assessment ofthe risks in order to determine the measures necessary forsafety ... MHSWR requires a consideration of: the work to be undertaken, including equipment etc the nature of the working environment

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levels of competence arrangements for emergencies

If the assessment identifies risks associated with confinedspaces, then The Confined Spaces Regulations apply.

2 The Confined Spaces Regulations 1997There are three principal duties in these Regulations - what doyou think they might be?

... the three duties as defined by the Regulations are as follows: avoid entry into confined spaces if entry is unavoidable, a safe system of work must be followed adequate emergency procedures must be in place before work

starts

We will look at these three duties in turn in sections 2.12.3below. The HSE leaflet INDG 258 Safe work in confined spacesprovides a very good coverage of the requirements of the Regula-tions and we recommend that you read this leaflet in parallel withyour studies of the present book.

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2.1 Avoiding entry into confined spacesThis might be achieved by using remotely controlled equipment,for example, it may be practical for the inspection and cleaning ofsome sewers and other confined spaces.An possible alternative approach might be to unconfine thespace, so to speak*. It may be possible to remove wall panelsand so on; in the case of, say, ship building activities it may thusbe possible, by careful planning, to undertake some of the fitting-out before spaces become confined.

2.2 Safe system of workA safe system of work must provide a plan that covers all aspectsot the work - entry and egress, sequence of operations, environ-mental factors, PPE, and so on.When an assessment identifies that the hazards to be faced areparticularly serious, then a permit to work will be required; youcan be safe to assume that for confined space work, permits towork will almost always be necessary.As you will see later in your studies (section 4.3.6), other commonexamples of permits include: (permits to work in confined spaces) hot work permits permits to work on pressurised systems electrical permits permits to enter confined spacesYou will appreciate that before a permit to work can be author-ised, a permit to enter the confined space may be required, soenabling inspections to take place prior to work being undertaken.

* Incidentally, the spell checker was reduced to silence by the wordunconfine - it offered no alternatives.

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In the case of confined space working, the permit to work pro-vides: written authority for the space to be entered and for work to

start and finish time limits and correct sequences procedures and responsibilities of all those involved checks and precautions (for example, continuous atmospheric

testing may be required in deep excavations and tunnels andthe permit to work should provide specifications of the requiredequipment)

Q On that point, what requirements would you make for theperson carrying out the atmospheric testing?

A Atmospheric testing (or related activities such as setting upautomated air monitoring equipment) should be undertaken bysomeone wearing appropriate breathing apparatus, with a secondappropriately equiped worker (breathing apparatus, rescue lineetc), standing by.Remember that in this section we are looking at the requirementsof The Confined Spaces Regulations 1997; now to the thirdrequirement ...

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2.3 Emergency proceduresThese should form an integral part of the planning: communications methods equipment and training of the rescue team emergency lighting etc rescue practice runs shutting down processes etc provision of first aid alerting emergency servicesRescue equipment will include ropes, resuscitation equipment,communication equipment, breathing apparatus, fire fightingequipment and so on. The most sophisticated breathing appara-tus will be useless if it is too large to allow entry through (say) themanhole - the suitability of all equipment must be established aspart of the planning.

3 Typical confined space problemsThe following is by no means exhaustive.

3.1 Hazards presented by gases, fumes and vapoursUnder this heading, we can include: substances already present when work begins substances which are created by work activities substances which seep into the confined space as the work

progresses

Q Before reading further, you might like to think of someexamples for each of these three categories.

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A Compare your answer with the following: substances already present

remains of stored substances (ie in storage tanks) sludge and decaying matter (drainage systems, sewers

and so on) carbon dioxide, the product of acid rainwater reacting with

chalk, may be a hazard in underground pumping systemsand so on

substances created by work activities welding fumes, adhesives, solvents heat from human and machine activity oxygen enrichment from use of oxy/acetylene and similar

equipment substances seeping from elsewhere

as a result of accidental damage to pipelines etc a consequence of seepage of air currents bringing contami-

nants into the confined space, for example: exhaust fumesfrom nearby plant such as dumper trucks and compressors

As we mentioned in the book on construction safety, because ofthe dangers presented by carbon monoxide, petrol or diesel plantshould never be operated in a confined space.

3.2 Oxygen deficiencyOxygen deficiency may occur as a result of organic decay proc-esses using up oxygen or as a result of an area being purged bythe use of an inert gas such as nitrogen. This may also benecessary to flush out explosive gases such as methane. Furtherpurging with air may be required before the space is safe to enter.(You will appreciate that the problem of oxygen deficiency relatesclosely to the issues we have just discussed.) The normal atmos-pheric concentration of oxygen is about 21% and, if the oxygenlevel falls below 17%, workers will rapidly suffer problems offatigue, unconsciousness and so on.

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3.3 Fire, explosion and other hazardsA fire or explosion in a confined space represents a very seriousthreat and a range of precautions will be necessary in situationswhere such problems may arise; these precautions include: use of intrinsically safe electrical equipment (ie equipment

which produces no sparks) continuous monitoring of the atmosphere provision of adequate ventilationWe deal elsewhere with the problems associated with heat stress,problems which are particularly likely in confined spaces. At thispoint, we will mention the hazards associated with workers beingtrapped in cold food storage facilities: alarms and emergencyescape devices may be required.

4 Reducing confined space hazaardsThis section forms a summary of the procedures and practiceswhich we have discussed in this book. safe systems of work use of permits to enter and permits to work substance substitutions: for example use of water-based

adhesives rather than solvent-based. continuous monitoring of environmental conditions, especially

atmospheric contaminants and oxygen levels provision of adequate ventilation exclusion of ignition sources purging of (in particular) flammable and explosive gases

Confined spaces1 Confined spaces, an introduction 2 The Confined Spaces Regulations 1997 2.1 Avoiding entry into confined spaces 2.2 Safe system of work 2.3 Emergency procedures 3 Typical confined space problems 3.1 Hazards presented by gases, fumes and vapours 3.2 Oxygen deficiency 3.3 Fire, explosion and other hazards 4 Reducing confined space hazaards

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Confined Space