Guidelines to Safe Working in Confined Space

Transcription

1 What is Confined Space? Confined space is a space which has limited accessibility, unfavorable natural ventilation and it is not design for continuous occupancy. Confined spaces include, but not limited to storage tanks, silos, sewers, compartment of ships, pits, tunnels, pipelines, vats, boilers and enclosed drains. Storage Tank Silo Manhole Septic Tank Boiler Pipeline 1

2 Hazards in Confined Space a. Lack of Oxygen 10% 12% 15% 19.5% 21% Oxygen Enriched No Oxygen Health Effect Concentration (%) 1 < 10% Inability to move. Fainting almost immediate. Loss of consciousness. Convulsions. Death. 2 10% - 12% Very poor judgment and coordination. Impaired respiration that may cause permanent heart damage. Possibility of fainting within a few minutes without warning. Nausea and vomiting 3 12% - 15% Poor judgment. Faulty coordination. Abnormal fatigue upon exertion. Emotional upset. 4 15% % Impaired thinking and attention. Increased pulse and breathing rate. Reduced coordination. Decreased ability to work strenuously. Reduced physical and intellectual performance without awareness. 5 21% Safe to enter 2

3 b. Flammable Atmosphere Flammable atmosphere is caused by flammable fuels, paint, cleaning solvents, combustible dust (such as metal), naturally occurring reactions that produce methane gas, or hydrogen from boiler cleaning or battery charging. Different gas has different flammable ranges. An explosive will result if source of ignition introduce into a space which have flammable atmosphere. Oxygen Explosion Fire Gas, Vapor, Fuel Ignition Excessive Oxygen in the atmosphere can cause flammable material to burn easily when ignited. Therefor never ventilate a confined space with oxygen. 3

4 c. Toxic Atmosphere Toxic atmosphere comes from substances such as poisonous gases, fume, vapor, mists, solid material and dust. It generated in various process; 1. Product Stores in Confined Space product absorbed into the wall and gives off toxic gas when removed or cleaned out. For example; sludge removal from storage tank can release deadly Hydrogen Sulfide (H2S) 2. Work carry out in Confined Space for example welding, grinding, cutting, brazing, scrapping, painting and degreasing. Cleaning solvent for industrial used for cleaning purpose contains vapor which is toxic. 3. Work in area adjacent to Confined Space can produced toxicants which enter and accumulate in Confined Space d. Atmosphere Testing (Gas Testing) Before entering a confined space, gas test must be conducted to identify type of gases present. It is very important to know that some gases are heavier and some are lighter. The heavier gas will settle at the bottom on a confined space, for example Hydrogen Sulfide (H2S) and the lighter gas will settle at the top of a confined space, for example Methane (CH4). Therefore, it is necessary to conduct gas test in all areas (bottom, top, middle) of a confined space using a proper gas detector with valid calibration time. If testing result shows presence of toxic gas or oxygen deficiency, the space must be ventilated and re-tested before workers enter. If ventilation is impossible and entry is necessary, proper respiratory must be provided. 4

5 e. Ventilation Ventilation may be necessary to remove harmful gasses from confined space. You may also be able to increase the number of openings and therefore improve ventilation. Mechanical ventilation may be needed to make sure there is an adequate supply of fresh air. f. Isolation Isolation is a process by which a permit space is removed from service and completely protected against the release of energy and material into the space by such means as: blanking or blinding; misaligning or removing sections of lines, pipes, or ducts; a double block and bleed system; lockout or tagout of all sources of energy; or blocking or disconnecting all mechanical linkages. If gas, fume or vapor could enter the confined space, you need to isolate the pipework. In all cases, a check should be made to ensure isolation is effective. 5

6 g. Respiratory Respiratory is a device which allows worker to work safely in a confined space. 2 types of respirator commonly use while working in confined space. Air purifying respirator which filter dangerous substances in the air and air supplying respirator which known as Self Contained Breathing Apparatus (SCBA) to provide breathing air (for example used by Rescuer) Half mask respirator Full face mask respirator SCBA h. Competent Person Working in a confined space requires competent persons who has undergone training acquiring knowledge, understanding and skills in confined space Entry Supervisor (ES) responsible to determine the acceptable entry conditions Authorised Gas Tester (AGT) responsible to test and interpret the reading level of gaseous in confined space Authorised Entrant (AE) worker who enter a confined space Standby Person (SP) standby outside a confined space and must be in constant contact with Authorised Entrant. Emergency Rescue Team must be trained and equipped with rescue knowledge to provide proper rescue technique and equipment to workers inside confined space. 6

7 i. Personal Protective Equipment (PPE) Workers must be equipped with PPE before entering confined space. Proper PPE is essential to protect worker from physical hazards, for example falling on wet surface or falling down objects above head. PPE includes hard hat, safety shoes, body harness, glove, safety glasses and proper coveralls. j. General/Physical Hazard Temperature extreme temperature condition in confined space can cause problems to the workers. For example, if the space is steamed, it should be allowed to cool down before entry. Engulfment workers may encounter engulfment and suffocation when enter and trapped in space containing liquid, powdered material or fine flowable solid such as sand, grains, etc Noise excessive noise can affect hearing and communication between the workers. For example, warning shouts by the workers can go unheard. Wet surface slippery surface can cause falls and injuries. Some cases it also can cause death due to falls or electrical shocked in areas where electric equipment and tools are used Falling Objects workers should aware and alert of the possibility of falling object when they work inside a confined space especially when the opening in on top of them. 7

8 For further information about Confined Space, please contact us at; mydasafety 8