Confined Spaces - Workplace Safety and Health Council

7.10.2 Forms of Hazardous EnergyEnergy sources can come in many forms but not limited to electrical, mechanical, hydraulic,pneumatic, chemical, thermal, gravitational, ionising and non-ionising radiation. It is necessary toisolate all mechanical, electrical equipment and all other energy sources connected to a confinedspace to prevent them from unintentional activation. If gases or vapours can enter the confinedspace, physical isolation of pipelines, valves, and so on needs to be locked and tagged usinglockout and tagout procedures. In all cases, a check is required to ensure isolation is effective.7.11 General Requirements7.11.1 Openings of Confined SpacesBefore an entrance cover is removed, any known unsafe conditions shall be eliminated. Whenentrance covers are removed, the opening shall be promptly guarded by a railing, temporarycover, or other temporary barrier. This will prevent anyone from falling through the opening. Thebarrier or cover shall prevent foreign objects from entering the space and protect each employeeworking in it. If it is in a traffic flow area, adequate barriers shall be erected to divert the traffic.It is necessary to take precautions when opening the covers to tanks and within other confinedor enclosed spaces in the event the space is under pressure or hazardous materials have leakedfrom internal piping systems. It is important to leave at least two nuts on opposite sides of thecover in place until the cover can be cracked and any internal pressure has released.7.11.2 BarricadeIt is essential to use safety barriers to separate workers from hazards that cannot be reasonablyeliminated by other engineering controls. Selection of suitable barriers will depend on thenature of the hazard and the size of the area or equipment to be cordoned off. The supervisormust determine if safety barriers will be needed for the confined space entry prior to any workersentering the confined space.7.11.3 Communication/Warning SignsWarning sign/s can be used to inform workers about the confined spaces. It is critical for theworkers to know the location of the confined space, its hazards, the required safe work proceduresand permit to enter the confined space.For details on specifications for graphical symbols on safety colours and safety signs,kindly refer to Singapore Standard, SS508-2 : 2008 and SS508-4 : 2008.7.11.4 Confined Space Attendant (CSA)CSA should be appointed where any person enters or carries out any work in a confined spaceand remain outside the confined space to:• Monitor persons entering and working in the confined space;• Maintain regular contact with the persons in the confined space and when necessary assistthem to evacuate should the need arise; and• Alert the rescue personnel to activate the rescue operation in an emergency.7.11.5 Access and EgressWhere the possibility for inadvertent or unauthorised entry to a confined space exists, it isrequired to use appropriate means to prevent such an entry (e.g., a barrier or safety warning signthat is clear, legible and visible).A safe way in and out of the confined space should be provided for the individuals carryingout the work. Wherever possible, quick, unobstructed and ready access and egress should beallowed. It is essential that the means of escape be suitable for use by every individual whoenters the confined space so that he or she can escape quickly in an emergency.The size of openings used for access to and egress from confined spaces needs to be adequateto allow ready passage. Openings providing access need to be sufficiently large and free fromobstruction to allow the passage of persons wearing the necessary protective clothing andequipment, and to allow adequate access for rescue purposes. These openings need to bekept clear whenever a confined space is occupied. Where practicable, it is necessary to havean alternative opening for insertion of hoses, ventilation ducts, power lines and other cablesrequired for the work.Certain confined spaces may have design deficiencies which increase the level of entry risk toan unacceptable level. These include spaces whose openings are too tight for safe passage orwhich are of convoluted construction, or which involve excessive distances to a point of escape.Structural modifications (e.g., the making of temporary openings) will be necessary before entryis possible in these cases.Confined spaceNo unauthorised entry7.11.6 Display of Name and Identification BadgeThe person entering a confined space must display his name and identification badge at theentrance to the confined space. It is also the duty of the responsible person of the entrant toensure that he does the same.Figure 4: Examples of Confined Space warning signs.24 25