Enclosed Space Entry – Safety Campaign Bulletin
2014 Enclosed Space Entry Safety Campaign Bulletin
HSQE DEPARTMENT Page | 2
Enclosed Space Entry – Safety Campaign Bulletin
Table of contents Introduction ..................................................................................................................... 4 1.0 What is an Enclosed Space? .................................................................................... 4 2.0 Atmospheric Hazards ............................................................................................... 5 2.1 Products stored in the space: ................................................................................... 6 2.2 Gas Detectors .......................................................................................................... 11 2.2.1 TankScope ............................................................................................................ 11 2.2.2 Tubes and Multi-Channel Gas detectors .............................................................. 12 2.3 Oxygen ..................................................................................................................... 13 2.3.1 Oxygen Analyzer ................................................................................................... 15 2.4 Flammable gas ......................................................................................................... 15 2.5 Toxic gas .................................................................................................................. 16 2.5.1 Multimeters............................................................................................................ 17 2.6 Summary of the Various Gas Measuring Instruments ........................................... 19 3.0 Work being performed in a confined space ............................................................ 19 3.1 Temperature Extremes ............................................................................................ 20 4.0 Systematic Approach to Safety ............................................................................... 20 4.1 General Safety.......................................................................................................... 21 4.2 Correctly Monitor and Record ................................................................................. 22 4.2.1 Risk Assessment .................................................................................................. 22 4.3 Ventilation ................................................................................................................ 24 4.4 Temperature and Pressure Variation ...................................................................... 26 4.5 Isolation of space..................................................................................................... 27 5.0 Enclosed Space Entry Permit .................................................................................. 28 5.1 Procedures before entry .......................................................................................... 30 5.2 Procedures During entry ......................................................................................... 31 6.0 Enclosed Space Rescue .......................................................................................... 34 6.1 Enclosed Space Rescue – Action Plan ................................................................... 35 7.0 Entering an Enclosed Space with an Unsafe Atmosphere ..................................... 38 7.1 Cases Analysis ........................................................................................................ 39 7.2 Further Considerations............................................................................................ 42 8.0 Completion and Permit Closure .............................................................................. 43 9.0 Duties ....................................................................................................................... 44 10.0 Communication ...................................................................................................... 46 11.0 Closing Summary................................................................................................... 47 11.1 Key Points when Preparing to Evaluate the Atmosphere in a Compartment ...... 47 11.2 Evaluating the Atmosphere Secondary Locations................................................ 47 Appendix - I .................................................................................................................... 49 Appendix – II .................................................................................................................. 52 Appendix - III .................................................................................................................. 55 Appendix - IV.................................................................................................................. 56 Page | 3
Enclosed Space Entry – Safety Campaign Bulletin
Introduction Entering an enclosed space is a potentially hazardous activity on board a vessel. A vessel’s Company Management System (CMS) is required to contain “procedures, plans and instructions, including checklists as appropriate, for key shipboard operations concerning the safety of the personnel, ship and protection of the environment. The various tasks should be defined and assigned to qualified personnel”. The CMS will therefore include procedures for entering enclosed spaces. However, in spite of such procedures, incidents resulting in injuries or fatalities continue to occur. This Safety Campaign Bulletin contains guidance for anyone who may be required to enter an enclosed space. However, it is important to note that the information is intended to supplement, but not replace, CMS procedures as described in Fleet Instruction manual. The basic minimum standard for entry is contained in the 2011 edition of the MCA publication “The Code of safe Working Practices for Merchant Seamen” Chapter -17. Further advice on enclosed space entry may be found in IMO Resolution A.1050(27) “Revised Recommendations for Entering Enclosed Spaces Aboard Ships”. (See Appendix-IV)
1.0 What is an Enclosed Space? Personnel are sometime unsure about the conditions which turn a compartment into an enclosed space, requiring the necessary procedures for safe entry to be followed. In order to assist in the identification of such compartments, IMO has defined an enclosed space as being one which has any of the following characteristics: Limited openings for entry and exit; Inadequate ventilation; and Is not designed for continuous worker occupancy. Examples of enclosed spaces may include:
Ballast tanks
Duct keels
Battery Lockers Boilers Cargo compressor rooms Cargo holds¹ Cargo pump-room Cargo tanks Chain lockers CO2 Rooms
Engine crankcases Engine scavenge air receivers
Foam tanks
Fuel Oil tanks
Gas bottle storage lockers Inter barrier spaces
Lube Oil tanks
Oil spill dispersant tanks
Spaces affected by chemical spill Spaces affected by fire Stool spaces Void spaces
Waste oil tanks
Cofferdams Paint lockers Double hull spaces Potable water tanks Dry bulk tanks Sewage tanks ¹ Particularly when carrying oxygen-depleting or noxious cargoes
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Enclosed Space Entry – Safety Campaign Bulletin
It is recommended that a responsible and experienced officer carries out a risk assessment (RA) exercise to identify and record the enclosed spaces on board (as described in Company’s Procedure Manual Chapter-17).The exercise should be repeated periodically as conditions may change over time. If there is any doubt as to whether or not a particular compartment should be listed, it should be treated as an enclosed space until determined otherwise. Compartments next to enclosed spaces should also be considered. IMO defines an “adjacent connected space” as being “a normally unventilated space which is not used for cargo but which may share the same atmospheric characteristics with the enclosed space such as, but not limited to, a cargo space access way”. An example of an adjacent connected space may be a deck house containing a booby hatch leading to a cargo hold. The characteristics of the atmosphere in the deck house may be similar to that of the cargo hold if, for example, the booby hatch lid sealing arrangements are in poor condition and leak, resulting in similar atmospheric conditions within both compartments. It should also be borne in mind that vent pipes from an enclosed space may pass through compartments which are not necessarily adjacent. If the pipes are not in good condition, these compartments may also be affected. In a recent case, a cargo hold vent pipe ran through a forecastle store some distance away. The oxygen deficient atmosphere from the cargo hold leaked into the forecastle store via a hole in the vent pipe, causing a serious incident. If you are unsure whether or not a compartment is safe to enter you should
assume that it is an enclosed space Similarly, tankers constructed with heavy external deck frames may find that pockets of gas build up outside the access ports if the frames hinder natural surface ventilation. These, and all other possibilities, should be considered when the risk assessment is carried out.
2.0 Atmospheric Hazards By far the biggest cause of incidents within enclosed spaces is a hazardous atmosphere due to:
Insufficient oxygen to support human life. Flammable (hydrocarbon) gas which may also increase the risk of explosion. Toxic gas which may be fatal in certain concentrations.
Before entering an enclosed space, the amount of oxygen in the atmosphere must be checked. However, the presence of flammable or toxic gas will usually depend on the type of compartment and the properties of the cargoes previously carried. The Material Safety Data Sheets for such cargoes should be consulted to assist in determining the atmospheric hazards that may exist. If there is any doubt regarding the gases or vapors that may be encountered a risk assessment should be carried out. Prior to entry the atmosphere must be tested to check that oxygen levels are satisfactory and that flammable and/or toxic gases, where present, are within acceptable safe limits. When testing for gases it is important that all levels of the space are checked. Some gases are heavier than air (e.g hydrogen sulphide) and some are lighter (eg methane). Concentrations of Page | 5
Enclosed Space Entry – Safety Campaign Bulletin
Other Hazards Although the toxicity of H2S gas remains the primary hazard, lesser risks in the longer term may include corrosion within bunker tanks and pipelines, and damage to other system components. If the amount of H2S gas inside a tank exceeds the oxygen content, H2S may react with rust to form pyrophoric iron sulphide. Pyrophoric iron sulphide deposits may emit considerable heat when in contact with air and can be a source of ignition. As a by-product of this reaction, hydrogen and water are produced. If this contin-ues for some time and the tank atmosphere is humid, prolonged exposure to hydrogen may lead to fractures developing in the steel-work (known as hydrogen induced cracking) in areas subject to repeated tension and compression such as tank tops and floors.
Recommendations International Standards Organization (ISO) Fuel Standard ISO 8217:2010 limits the H2S content of residual and distillate marine fuels to 2 ppm (mg/kg) by weight in the liquid and not as vapour or gas concentration. Although the H2S limit does not apply until 1 July 2012, Members in the meantime may wish to stipulate ISO 8217:2010 with a maximum H2S content of 2 mg/kg when ordering bunkers in case such product is available. However, it should be borne in mind that tanks containing such bunkers may still produce H2S gas in concentrations which will be hazardous. Other recommendations include adding suitable guidance on the dangers of H2S in marine bunkers to the Safety Management System (SMS), providing vessels with a correctly calibrated H2S gas detector and personal monitors and training appropriate personnel in their use. Should it be necessary to enter a tank which has carried bunkers, it will be necessary to follow SMS procedures regarding enclosed space entry and test the atmosphere for oxygen and hydrocarbons beforehand. Safety may be further improved by carrying out a series of checks using the H2S gas detector. Since H2S is heavier than air, the tank atmosphere should be sampled at various heights to ensure that an accurate assessment of H2S gas can be made. Within the engine room fuel oils will be treated (purified), handled and heated to very much higher temperatures, which in turn will cause greater evolution of this gas. Notwithstanding the forced ventilation in this area, H2S being heavier than air will cause it to accumulate in the machinery space bilges and below the lower engine room plates. Under such circumstances Page | 53
Enclosed Space Entry – Safety Campaign Bulletin
access to these areas of the engine room should be treated in the same way as an entry into an enclosed space. If the odour of rotten eggs emerges from a tank when it is opened or if the gas detector indicates that H2S gas is present in quantities which exceed national or flag state exposure limits (typically 10 ppm), personnel should replace the tank lid immediately, evacuate the area and seek fresh air to breathe. If the smell of H2S gas is found to be coming from a bunker tank vent, the crew should be alerted immediately to this danger. All accommodation openings (doors and port-holes) should be kept closed at all times with clear notices posted in these locations as to the presence of H2S gas. Storage tanks that contain residual dirty oil should be emptied periodically to ensure there is no build up of H2S gas over time. Such tanks should also be tested regularly for the presence of H2S gas. Wherever possible, bunker storage tanks in machinery spaces that have sounding pipes that terminate within the space should be fitted with side level gauges so that the tank contents can be determined without opening the sounding pipe cap. As an additional safety measure, such sounding pipes may also be fitted with a gravity dead-weight closing device to minimize the possibly of them being left open inadvertently. Suitable notices should be posted to warn crewmembers that marine bunker tanks and residual dirty oil tanks may contain H2S gas, and of the associated symptoms and hazards.
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