Working in confined and restricted spaces

Work in spaces such as wells, tanks, silos and service ducts requires specific preparation. The air may be unsafe to breathe, access and exit may be difficult, and an injured person may need assistance to get out.

This information provides an initial guide to planning. The employer is responsible for ensuring that hazards are identified and the work can be carried out safely. This guidance must be supplemented by a documented risk assessment for the specific space and task.

What are confined and restricted spaces?

Confined spaces can include tanks, wells, silos and service ducts where air circulation is limited. Hazardous substances may accumulate or oxygen deficiency may develop. The space does not have to be small or fully enclosed. An open basin or deep pit may also need to be assessed.

Restricted spaces provide limited room to enter, move around, work or exit. Assisting an injured or unconscious person may also be difficult.

A space can be both confined and restricted. Always examine the conditions at the site and the hazards the work may create, even if you are unsure how to classify the space.

Plan the work using systematic work environment management

Start by considering whether the work can be carried out from outside. If someone needs to enter, use the Swedish systematic work environment management process, known as SAM:

EXAMINE → ASSESS RISKS → TAKE ACTION → CHECK

1. EXAMINE – establish the conditions

Find out what the space contains or has previously contained, which pipes and machinery are connected to it, and how the person will enter and exit.

In particular, check:

• whether air circulation is limited and hazardous substances or oxygen deficiency may be present,
• whether liquids, gases, steam or loose materials could enter,
• whether machinery could start or residual pressure and other stored energy could cause injury,
• whether there are risks of falls, crushing, electrical accidents, heat or infection,
• whether openings and passageways make access, evacuation or rescue difficult.

Also identify any hazards the work itself may create. Cleaning, welding and the use of chemical products can, for example, change the atmosphere inside the space.

2. ASSESS RISKS – consider what could happen

Assess how those carrying out the work could be harmed and how serious the consequences could be. Consider the entire task, from entry until everyone has left the space.

Also assess:

• whether conditions could change during the work,
• whether other activities or connected plant could affect safety,
• what would happen if ventilation, communication or equipment failed,
• how an injured or unconscious person would be brought out.

Document the risk assessment and the protective measures required.

3. TAKE ACTION – put protective measures in place before starting

Prevent start-up and the entry of hazardous substances or materials

Stop and secure machinery so that it cannot start during the work. Disconnect and secure energy supplies, and safely release or control residual pressure and other stored energy.

Prevent liquids, gases, steam or materials from entering the space. Check that the isolation measures provide the necessary protection and that no one can accidentally reconnect or restart the equipment.

Check the atmosphere and arrange ventilation

Do not assume that the air is safe because there is no unpleasant smell or because a hatch has been opened.

As a general rule, oxygen levels, substances hazardous to health, and flammable gases and vapours must be measured before work begins. Testing must be carried out using suitable equipment and by someone who can assess the results. Measurements may be needed at several locations and heights.

Any exemption from testing requires a documented risk assessment showing that testing is clearly unnecessary.

Determine how the space will be ventilated and whether ongoing atmospheric monitoring is needed. Acceptable readings before entry do not mean that the atmosphere will remain safe throughout the work.

Filtering respirators do not protect against oxygen deficiency. If the composition of the atmosphere is unknown, breathing apparatus is required. Such work requires specific knowledge, equipment and planning.

Assign responsibilities and establish instructions and monitoring

Everyone involved must know:

• what the work involves and which hazards are present,
• which protective measures and equipment must be used,
• who will monitor the work and how contact will be maintained,
• when work must stop and the space must be evacuated,
• how assistance and rescue will be provided.

Check whether a written permit to work is required. This applies, among other situations, to work in spaces with limited air circulation where flammable liquids, gases or aerosols are handled or generated. Site procedures may also require a permit to work in other situations.

Do not work alone. Someone must remain outside the space to maintain contact, monitor the work and initiate the planned assistance.

Prepare for rescue

Determine how to rescue a person who cannot get out without assistance. The plan must work for the specific space, including if the person is unconscious.

Where possible, plan the rescue so that the person can be retrieved without anyone else having to enter. A lifting device must be ready to enable rapid retrieval, unless this is clearly unnecessary.

Check that the openings, passageways and equipment allow the planned rescue to be carried out. Suitable equipment and people who know how to use it must be available. Practise the rescue to verify that it works. Simply planning to call 112 is not enough.

Do not enter to help someone without first ensuring that the rescue can be carried out safely. The same hazardous atmosphere can also incapacitate the person attempting to help.

4. CHECK – verify that the work can be carried out safely

Before starting, check that the protective measures are in place and working, that everyone understands the instructions, and that the rescue arrangements are ready.

Monitor conditions during the work. If an alarm activates, a protective measure fails, or conditions change so that safety can no longer be assured, stop work and leave the space.

Work may resume only after the risks have been reassessed and the necessary protective measures have been implemented and checked.

Choose equipment for both work and rescue

The choice of equipment depends on how the person will enter, work inside and leave the space.

When entering using a ladder, fall protection and a rescue lifting device ready for use may be needed. If the person will be lowered or lifted during normal work, equipment specifically intended for that use is required.

A rescue lifting device is not automatically approved for transporting people during work. The harness, anchorage, fall protection and rescue equipment must be compatible and used according to the manufacturers’ instructions.

Fall protection and rescue equipment do not protect against a hazardous atmosphere. Atmospheric testing, ventilation and other protective measures must be planned separately.

Regulations and guidance

SAM provides a process for examining conditions, assessing risks, taking action and checking the results. It does not replace the specific requirements that apply to the work.

Relevant Swedish regulations include AFS 2023:1 on systematic work environment management, AFS 2023:10 on risks in the work environment, and AFS 2023:11 on the safe use of work equipment and personal protective equipment. Requirements for atmospheric testing, permits to work, monitoring and lifting equipment ready for use are primarily set out in AFS 2023:10, Chapter 9, Sections 5–9.

Contact Hewall Safety for assistance in selecting personal fall protection equipment and rescue equipment for your planned working method.