Entry Into Enclosed Spaces Prepared by Steve Benstead

Enclosed Spaces

Enclosed Spaces Any of the following spaces may be considered to be potentially dangerous. Ballast tanks Fuel oil tanks Void spaces Cofferdams Cargo tanks Cargo holds Pump rooms Boilers Pressure vessels Double hull spaces Sewage spaces Compressor spaces Duct keels Engine crankcases

Enclosed Spaces A confined space means a space that has any or all of the following characteristics. Limited openings for entry and exit. Unfavourable natural ventilation Not designed for continuous worker occupancy

Enclosed Spaces Identifying potential hazards. Working in confined spaces has a greater likelihood of causing fatalities, and severe injuries. Risk of Fire or Explosion Loss of Consciousness Asphyxiation. Drowning. Heat exhaustion.

Enclosed Spaces Oxygen Deficiency. If an empty tank or other confined space has been closed for a period of time the oxygen content may have been reduced for a number of reasons. Rusting may have occurred. (The iron in the steel recombines with oxygen.) Oxygen absorbing chemicals may have been present. Oxygen absorbing cargoes may have been carried. Gasses from volatile cargoes may have displaced the oxygen. Hydrogen may have been produced by the cathodic protection system. Oxygen may have been displaced by the use of carbon dioxide or other fire extinguishing medium. Oxygen may have been displaced by inert gas in cargo tanks or inter-barrier spaces.

Enclosed Spaces Toxicity of Oil Cargoes. Hydrocarbon gases are flammable as well as toxic, they may be present in fuel or cargo tanks. Hydrocarbon gases may also be present in pump rooms, cofferdams, duct keels and other spaces adjacent to cargo tanks.

Enclosed Spaces Toxicity of Other Substances. Cargoes carried in chemical tankers or gas tankers may be toxic. There may be leakage from drums of chemicals or other packages of dangerous goods . Trace components of inert gas such as carbon monoxide, sulphur dioxide, nitric oxide and nitrogen dioxide. Hydrogen sulphide Chemical cleaning, painting, or the repair of tank coatings may release solvent vapours.

Enclosed Spaces Flammability. Flammable vapours may be still be present, after cleaning in cargo or other tanks that have contained oil products or chemical or gas cargoes. Cofferdams and other spaces adjacent to cargo and other tanks may contain flammable vapours if there has been leakage into the space.

Enclosed Spaces Other hazards. The inhalation of contaminated air is the most likely route by which harmful substances enter the body, however it must be borne in mind that some chemicals may enter the body by absorption through the skin. Some cargoes carried by chemical tankers and gas carriers are irritants or corrosive if allowed to come into contact with the skin. The disturbance of rust scale or sludge residues particularly from cargoes of animal, vegetable or mineral origin, or of water which could be covering such substances may lead to the release of toxic or flammable vapours.

Enclosed Spaces Entering Enclosed or Confined Spaces An enclosed space should only be entered when, based on the findings of a risk assessment, appropriate control measures have been put in place.

Enclosed Spaces Precautions Before Entering an Enclosed Space. A competent person should make an assessment of the space. A responsible officer should be appointed to take charge of the operation. A risk assessment should be carried out. The atmosphere of the space should be tested. A “Permit To Work” system should be in place. Where possible the space should be ventilated for at least 24 hours prior to entry.

Enclosed Spaces

Enclosed Spaces Preparing and Securing the Space for Entry. When opening the entrance for the first time precautions should be taken in case the space is pressurised or under vacuum. The space should be isolated by blanking of pipelines or securing valves, notices should be placed on relevant controls and the OOW informed. The atmosphere should be tested. If necessary any sludge or deposits likely to give off gasses should be removed. The space should be thoroughly ventilated either by natural or mechanical means. Compressed oxygen should not be used to ventilate any space. Where necessary pumping operations or cargo movements should be suspended.

Enclosed Spaces Testing the Atmosphere. Should be carried out by persons trained in the use of the equipment. Testing should be carried out before entry and at regular intervals thereafter. If possible testing the atmosphere before entry should be done remotely. Where appropriate the space should be tested at different levels.

Enclosed Spaces Testing for Oxygen Deficiency. A steady reading of at least 20% oxygen should be obtained. A combustible gas indicator cannot be used to detect oxygen. Equipment designed for personal use is only designed to provide a warning of oxygen deficiency and hydrocarbon vapours when there is a change of conditions and should not be used to determine whether the space is safe to enter.

Enclosed Spaces A Combustible Gas Indicator sometimes called an “explosimeter “ should be used to detect flammable gasses. Testing for toxic gasses should be carried out using equipment specifically designed for the purpose such as “Draeger Tubes”

Enclosed Spaces Permit to Work Systems. Entry into a potentially dangerous enclosed space should be planned in advance and use should be made of a “Permit To Work System”.

Enclosed Spaces Procedures Before Entry. Access to and within the space should be adequate and well illuminated. No source of ignition should be present. Rescue and resuscitation equipment should be made available at the entrance. The number of persons entering the space should be limited to those who actually need to work in the space. A rescue harness should be worn by every person entering the space. At least one person should be detailed to standby at the entrance to the space. An agreed and tested means of communication should be in place. The OOW should be informed. Before entry is permitted it should be established that entry with a SCBA is possible.

Enclosed Spaces Safety Equipment. SCBA with fully charged spare cylinders. Oxygen resuscitation equipment . Life lines and a rescue harness. A means of hoisting an incapacitated person from the space. A stretcher. Torches or lamps approved for use in a flammable atmosphere. A first aid kit.

Enclosed Spaces Arrangements during entry. Ventilation should continue during the period that the space is occupied. If the ventilation fails persons should leave the space. The atmosphere should be tested periodically while the space is occupied. If unforeseen difficulties or hazards develop, work in the space should be stopped. Permits to Work should be withdrawn and re-issued after the situation has been re-assessed. Communication should be maintained between those in the tank, the person on standby at the entrance, and the OOW. Should an emergency occur the general alarm should be sounded and a back up team made available. The person standing by at the entrance should not in any circumstances enter the space.

Enclosed Spaces Entry to a Space where the Atmosphere is Unsafe. If the atmosphere in the space is known to be unsafe, entry should be restricted to occasions when entry is essential for testing purposes, for the safety of life or safety of the ship, or for the working of the ship. SCBA should always be worn. The number of persons entering the space should be kept to a minimum.

Enclosed Spaces Air Supply. Except in the case of an emergency, or where it would be impracticable because movement in the space would be impeded, two air supplies should be available. Lifelines. Wherever practicable life lines and safety harnesses should be used. PPE. Where chemical hazards are involved the correct PPE should be available. Training. Employers should provide any necessary training for employees.

Enclosed Spaces Breathing Apparatus. No one should enter a space where the atmosphere is unsafe or is suspected to be unsafe without wearing a breathing apparatus. Equipment may consist of two air supplies; A conventional SCBA. A compressed air line breathing apparatus incorporating an emergency self contained supply.

Enclosed Spaces When determining the capacity of a SCBA it must be borne in mind that under stress or difficult conditions the wearers breathing rate may be in excess of 40 litres per minute.

Enclosed Spaces

Enclosed Spaces Everyone likely to use breathing apparatus should be instructed by a competent person in its proper use. The responsible officer and the person about to enter the space should undertake the full pre-wearing checks and donning procedures recommended by the manufacturers. There is sufficient air at the correct pressure. The low pressure alarms are working correctly. That the face mask fits correctly.

Enclosed Spaces