.enclosed space

Enclosed spaces are spaces that have limited openings for entry and exit, inadequate ventilation and are not designed for continuous worker occupancy. The atmosphere in any enclosed space may be oxygen-deficient or oxygen-enriched and/or contain flammable and/or toxic gases or vapours, thus presenting a risk to life.

The new regulation in SOLAS chapter XI-1–  Atmosphere testing instrument for enclosed spaces, requires ships to carry an appropriate portable atmosphere testing instrument or instruments, capable, as a minimum, of measuring concentrations of oxygen, flammable gases or vapours, hydrogen sulphide and carbon monoxide, prior to entry into enclosed spaces

The most common confined spaces onboard ships are cargo holds, chain lockers, cofferdams, water tanks, void spaces, duct keels, fuel tanks, engine crankcases, exhaust and scavenge receivers.

Dangers and hazards associated with enclosed spaces can be –

.dangers of enclosed space

1. Lack of oxygen – the acceptable range of oxygen in an enclosed space is between 19.5% to 23.55. Oxygen in any compartment can reduce due to many factors- rusting of steel parts is the most common one. We all know that rusting is nothing but the process of oxidation-thus oxygen is consumed. Oxygen can also be consumed by activities like hot work, welding or the occurrence of fire.

Inert gases entering the space can also deplete the oxygen content. The remaining traces from discharged cargoes such as iron ore, coal can absorb oxygen.

2. Hazardous vapours– Because of zero ventilation, these enclosed places generate and store toxic gases which are either produced from chemicals stored in the place or leakage from pipelines. If a person enters such a place without taking precautions, he or she may suffer unconsciousness and sometimes even death.

3. Insufficient/no ventilation – there could be high chances of the presence of toxic gases or absence of oxygen, both cases being lethal for man entry.

4. Restricted space– restricted or limited space in any compartment can make rescue attempts from such chambers difficult and challenging. Personnel should understand the layout of an enclosed space before attempting entry.

5. Inadequate lighting.

6. Personal injury due to slips, trips, and fall.

Procedure for Entering an Enclosed Space : Enclosed Space Entry

.enclosed space entry procedure    .esep   .eser

The following are the points that need to be followed before entering an enclosed space:

• Risk assessment to be carried out by a competent officer as enclosed or confined space entry is deficient in oxygen, making it a potential life hazard.
• A list of work to be done should be made for the ease of assessment for e.g. if welding to be carried out or some pipe replacement etc. This helps in carrying out the work quickly and easily.
• Potential hazards are to be identified such as the presence of toxic gases
• Opening and securing has to be done and precaution should be taken to check if the opening of enclosed space is pressurized or not
• All fire hazard possibilities should be minimized if hot work is to be carried out. This can be done by emptying the fuel tank or chemical tank near the hot workplace
• The confined space has to be well ventilated before entering. Enough time should be allowed to establish a ventilation system to ensure that air containing enough oxygen to sustain life is introduced. Ventilation can either be natural or mechanical using blowers.
• Space has to be checked for oxygen content and other gas content with the help of an oxygen analyzer and gas detector. Atmosphere testing instruments should be able to measure the presence of carbon monoxide and hydrogen sulphide. Tests should be carried out at different levels of the enclosed space, the top, middle and the bottom and through as many openings as possible to obtain a representative sample of the atmosphere in the space

.enclosed space hazard

METHANE – RISES TO THE TOP AS IT IS LIGHTER THAN AIR

CARBON MONOXIDE– STAYS IN THE MIDDLE AS IT IS THE SAME WEIGHT AS AIR

CARBON DIOXIDE – SINKS TO THE BOTTOM AS IT IS HEAVIER THAN AIR

• The oxygen content should read 20% by volume. A percentage less than that is not acceptable and more time for ventilation should be given in such circumstances.
• Enough lighting and illumination should be present in the enclosed space before entering.
• A proper permit to work has to be filled out and a checklist to be checked so as to prevent any accident which can endanger life. A confined space should only be entered with an authorized and issued permit and by a trained and competent person. The permission to work in an enclosed space specifies:
  – The location of the work
  – The nature and limitations of the work
  – Details of the working team and tools to be used
  – Potential hazards
  – Precautions are taken
  – Protective equipment to be used
  – Time of issue and its validity
  – Agreed communication methods and intervals
  – Signature of the person on issuing the permit and on completion of the work
  – Signature of the person who is supposed to enter thus confirming he has been advised on the hazards and the precautions to be observed

• Permit to work is to be valid only for a certain time period. If the time period expires then again new permit is to be issued and the checklist is to be filled out.
• Permit to work has to be checked and permitted by the Master of the ship in order to work in a confined space
• Proper signs and Men at work signboards should be provided at required places so that person should not start any equipment, machinery or any operation in the confined space endangering the life of the people working
• The duty officer has to be informed before entering the enclosed space
• The checklist has to be signed by the person involved in entry and also by a competent officer
• One person always has to be kept on standby to communicate with the person inside the space.
• Effective communication between the people inside the space and the person standing by is vitally important. The communication system must be agreed upon and tested. The standby person must, in turn, be able to communicate with the officer of the watch