Enclosed Space Definition and Entry Procedure

Definition of Enclosed Spaces

Enclosed spaces are areas with limited openings for entry and exit, inadequate ventilation, and not designed for continuous worker occupancy. The atmosphere in these spaces may be oxygen-deficient or oxygen-enriched, and/or contain flammable and/or toxic gases or vapours, presenting a risk to life[1].

Common Enclosed Spaces on Ships

• Cargo holds
• Chain lockers
• Cofferdams
• Water tanks
• Void spaces
• Duct keels
• Fuel tanks
• Engine crankcases
• Exhaust and scavenge receivers

Dangers and Hazards

1. Lack of oxygen: Acceptable range is 19.5% to 23.5%. Causes of oxygen depletion include rusting of steel parts, hot work, welding, fire, inert gases, and traces from discharged cargoes[1].
2. Hazardous vapours: Generated and stored due to zero ventilation, can cause unconsciousness or death[1].
3. Insufficient/no ventilation
4. Restricted space: Makes rescue attempts difficult[1].
5. Inadequate lighting
6. Personal injury risks: Slips, trips, and falls[1].

Entry Procedure

1. Risk assessment by a competent officer
2. Create a work list
3. Identify potential hazards
4. Open and secure the space
5. Minimize fire hazards
6. Ventilate the space (natural or mechanical using blowers)
7. Check atmosphere (use oxygen analyzer and gas detector, test at different levels)
8. Ensure proper lighting
9. Complete permit to work
10. Inform duty officer
11. Post proper signage
12. Assign a standby person
13. Establish effective communication

Safety Equipment

Ships must carry portable atmosphere testing instruments capable of measuring oxygen concentrations, flammable gases or vapours, hydrogen sulphide, and carbon monoxide[1].

Key Points to Remember

• Always conduct a risk assessment before entry
• Ensure proper ventilation and atmosphere testing
• Use appropriate safety equipment
• Maintain effective communication
• Follow all procedures and obtain necessary permits