What counts as a confined space?
HSE describes a confined space as any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions, such as a lack of oxygen.
So a space isn’t confined just because it’s small or awkward to work in. What matters is that it’s enclosed or largely enclosed, and that there’s a foreseeable risk of serious harm. HSE also points out that a space can become confined because of the work being done in it.
| Easy to identify | Less obvious, but can be just as dangerous |
|---|---|
| Storage tanks | Open-topped chambers |
| Silos | Vats |
| Reaction vessels | Ductwork |
| Enclosed drains | Combustion chambers in furnaces |
| Sewers | Rooms with little or no ventilation |
HSE says it isn’t possible to give a complete list, so each space has to be assessed for the work you plan to do.
Why are confined spaces so dangerous?
HSE says a number of people are killed or seriously injured in confined spaces in the UK each year, including people who try to rescue others without the right training and equipment. The dangers it lists include:
- Lack of oxygen: this can be caused by rust forming inside steel tanks, among other things.
- Poisonous gas, fume or vapour: these can build up in sewers and pits, or come in through connecting pipes.
- Liquids and solids: these can suddenly fill the space, or release gases when disturbed.
- Fire and explosion: for example, from flammable vapours.
- Residues: those left in tanks or on internal surfaces can give off gas or fumes.
- Dust: high concentrations, such as in flour silos.
- Heat: hot conditions can dangerously raise a person’s body temperature.
Cleaning can add to these risks. Disturbing a residue or using a chemical in an enclosed space can create a hazard that wasn’t there before.
What do the Confined Spaces Regulations require?
If your risk assessment finds a risk of serious injury from working in a confined space, the Confined Spaces Regulations 1997 apply. HSE sums up the key duties as:
- Avoid entry to confined spaces, for example by doing the work from outside.
- Follow a safe system of work if entry can’t be avoided.
- Put adequate emergency arrangements in place before the work starts.
Can you clean it without going in?
That’s the first question to ask, because HSE says inspection, sampling and cleaning can often be done from outside the space with the right equipment. Remote cameras can be used to look inside, and some blockages can be cleared remotely. We look at this at the site survey, before we plan anyone’s entry.
What goes into a safe system of work?
If someone does have to go in, HSE’s checklist includes:
- a supervisor who is responsible for checking safety at each stage
- people who are suitably trained, experienced and fit for the work
- mechanical, electrical and pipework isolation, with a check that it has worked
- cleaning before entry, where residues could give off fumes
- an entrance big enough to get in and out with all the equipment
- ventilation, and air testing by a competent person with a calibrated gas detector
- suitable tools and lighting, plus breathing apparatus if the air can’t be made fit to breathe
- a permit to work, where the risk calls for one
HSE warns that you should never try to “sweeten” the air with oxygen, as it can greatly increase the risk of a fire or explosion.
What should the emergency plan cover?
HSE is clear that it’s not enough to rely on the emergency services. The plan needs to cover how the alarm is raised, including at night and at weekends, who stays outside to keep watch, and what rescue and resuscitation equipment is on hand. It also needs training and practice drills.
Who is responsible: you or the contractor?
Usually, both of you. A contractor is responsible for its own people and its own method of work. As the site owner or occupier, you know what the space has held, what’s connected to it and what else is happening on site, and you need to pass that on.
Before the work starts, it helps to agree:
- who isolates the plant and who checks it
- what has been stored in the space, and any safety data sheets
- whether your permit-to-work system applies, and who signs it
- how the emergency plan fits with your own site procedures
- how any waste from the space will be removed
What should you ask a confined space contractor?
- Can the work be done without entering the space?
- Who will carry out the risk assessment, and can we see it?
- What confined space training do your operatives hold?
- Who will supervise, and who stays outside?
- How will you test and monitor the air?
- What’s your rescue plan, and has it been practised?
- How will you dispose of the waste, and what paperwork will we get?
Read more about our confined space cleaning. It often forms part of a wider industrial clean.
