Confined space is an area not necessarily designed for people, but are large enough for workers to enter and perform certain jobs; it has limited entry and egress. Confined spaces include tanks, vessels, silos, storage bins, hoppers, vaults, pits, manholes, tunnels, equipment housings, duct-work, pipelines, etc.
Characteristics of a confine space:
For a space to be considered as a confine space, it should have the following characteristics:
- Not designed for sustained occupancy.
- Has a potential for significant hazard.
- Has limited or restricted means of entry or exit.
- It is enclose in nature.
- Though not designed for people, but are large enough for workers.
According to the OSHA, a permit-required confined space (Confine space) should have the following characteristics:
- Contains or has the potential to contain a hazardous atmosphere.
- Contains a material that has the potential for engulfing the entrant.
- Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section.
Contains any other recognized serious safety or health hazards.
Hazards of a confine space
- Lack or reasonably foreseeable lack of oxygen: Will result to asphyxiation, fainting and death.
- Excess of oxygen: This will increase the risk of explosion. Safe oxygen concentration is considered between 19.5% and 23.5%
- Flammable or explosive atmospheres: If all conditions are met, fire/explosion can occur.
- Harmful gas, fume or vapour.
- Free flowing solid or an increasing level of liquid: This can result to drowning, suffocation, burns, etc.
- Excessively high temperature: This can increase the risk of heat stroke or collapse from heat stress, if conditions are excessively hot. The risk may be exacerbated by the wearing of personal protective equipment or by lack of ventilation.
Safety requirements for working in a confine space
- Assess the risk of the confine space
A competent person must prepare a written assessment of the risk of the confine space. This risk assessment will cover, working inside the confine space and working in or near the confined space. Confine space entry being a high risk task, close supervision and monitoring should be maintained.
During the process of carrying out the risk assessment, some pertinent question must be asked.
- Can the work be done without entering the space?
- What is the nature of the space?
- What is the amount of oxygen and airborne contaminants?
- Is the amount of the oxygen and contaminant likely to change?
- What is the type of job to be carried out in the space?
- What emergency and rescue procedures will be best suited for the confine space.
The result of the risk assessment should be properly communicated and implemented. The risk assessment should be reviewed as at when necessary.
- A work permit should be designed for confine space entry
Before someone enters a confined space, an entry permit (written by a competent person) should be issued.
The permit will contain:
- Description of the space
- Names of those allowed to enter the space
- Permit validity period
- What to do before work commences, and during the work.
- A section for the competent person to acknowledge that everyone has left the space.
N/B: Permit applies to one space only, but it allows one or more workers multiple entries.
- Communication plan with those inside the confine space
Someone must be on stand-by to continuously monitor the conditions inside a confined space from outside the space. The stand-by person outside the space must start emergency procedures when necessary; he must never enter the space to attempt a rescue.
- Rescue/Evacuation plan
Where a system of entry permits is in place, a rescue plan is required. It will list the personnel and equipment required to be at the work-site before entry is allowed. Special equipment such as tripod hoists, harnesses, and others may be required to extricate a worker from a toxic environment, without unduly endangering rescue personnel.
Summary of safety measured to be considered include:
- Erect signs and barricades in the area to prevent unauthorized entry.
- Make sure the air is safe.
- Get rid of ignition sources.
- Provide adequate lighting when necessary.
- Provide artificial ventilation when necessary.
- Have emergency procedures.
- Keep plant, equipment and PPE in good working order.
- Train your workers.