Confined spaces pose dangers because they are usually not designed to be areas where people work. Confined spaces often have poor ventilation which allows hazardous atmospheres to quickly develop, especially if the space is small.
Working in a confined space can be fatal, because of a lack of oxygen, an explosion or airborne contaminants. Incidents can occur when someone becomes swallowed up in flood waters, sewerage, smoke or dirt.
Confined spaces can be found in vats, tanks, pits, pipes, chimneys, silos, sewers, shafts, wells, pressure vessels, trenches and tunnels.
This video from overseas highlights how a confined space can change between being safe and dangerous.
There are specific laws about working safely in confined spaces. Here we summarise those laws and give you some practical tips.
Some requirements relate to designers, manufacturers, importers, suppliers, installers and constructors of plant and structures, while others are more general.
For designers, manufacturers, importers, suppliers, installers and constructors of plant and structures
Where you can, ensure there is no need or way for anyone to enter a confined space, either on purpose or by accident. Otherwise, minimise the need or risk of people entering the space, make sure it has safe entry and exits, and minimise (or where you can eliminate) the risks to the health and safety of anyone who enters the space.
General requirements for employers
Assess the risks
Someone with the right knowledge and skills must prepare a written assessment of all the possible risks of entering, or working in or near, a confined space. That person needs to review and revise it when necessary, and it should include:
- whether the work can be done without entering the space
- the nature of the space
- the amount of oxygen and airborne contaminants in the space – and whether the amount is likely to change
- the type of work, the range of options for doing the work and how it will be carried out
- emergency and rescue procedures.
Use a permit
Before someone enters a confined space, you must give them an entry permit (written by a competent person) that includes:
- a description of the space
- the names of those allowed to enter the space
- the time the permit is valid
- the things to do before work commences (eg cleansing and entry) and during work (eg continuous communication with, and monitoring of, workers)
- a section for the competent person to acknowledge that everyone has left the space.
The permit applies to one space only, but it allows one or more workers multiple entries.
When the work is finished, make sure the acknowledgment confirms that everyone has left the space.
Erect signs and barricades
Prominently display signs near the confined space entries, banning entry to anyone not listed on the entry permit. Also, install locks and fixed barriers.
Communicate with and monitor those inside
A stand-by person must continuously monitor the conditions inside a confined space from outside the space, and where they can, observe the work being carried out. You must be able to order the workers to get out, communicate with them at all times, and start emergency procedures when necessary. The stand-by person must never enter the space to attempt a rescue.
Minimise or, if you can, eliminate risks resulting from any plant or services connected to the confined space. Also, prevent contaminants entering the space through pipes, ducts, vents, drains, conveyors and the like.
Make sure the air is safe
Clean the air in the space regularly, keep it well ventilated, safely purge any contaminants, and carry out atmospheric testing before anyone enters. Use an appropriate respirator if you are unable to keep safe oxygen levels.
Get rid of ignition sources
Get rid of all ignition sources that could cause a fire or explosion. Ensure the amount of flammable gas, vapour or mist in the space is less than five per cent of its lower explosive limit (LEL). If the LEL is greater than five but less than 10 per cent, you must use a flammable gas detector and if the LEL is greater than 10 per cent, no-one should be in the space.
Have emergency procedures
Your workplace must have good first aid and rescue procedures, and you need to practise them.
Make sure openings in the space are large enough to allow emergency access and are not obstructed. Also, make sure appropriate personal protective equipment (PPE), like air-supplied respiratory equipment, is made available to workers carrying out emergency tasks.
Finally, keep plant, equipment and PPE in good working order.
Train your workers
Your workers and their supervisors must understand the risks of a confined space, the controls that are in place, what they need to do and what a permit allows.
Keep a copy of your risk assessment for at least 28 days after the work in the space has finished, and keep a copy of the permit at least until the work is completed. If there is an incident in the space, keep the records for at least two years.
Keep a record of worker training for two years.
These records must be made available to us and any worker upon request.
For the specific laws about working safely in confined spaces, see clauses 62 – 77 of the Work Health and Safety Regulation 2017.
There are also general work health and safety laws that will apply to you in any situation, including when working in confined spaces.
For general information about working in confined spaces, see the code of practice for confined spaces. It includes a checklist and sample entry permit.
For information about risk management, training and emergencies, and tips about cleansing confined spaces and atmospheric testing, see AS/NZS 2865: 2009 Confined spaces.
For information about the advantages and disadvantages of different types of respiratory protective equipment, see AS/NZS 1715: 2009 Selection, use and maintenance of respiratory protective equipment.