Hazards in the Workplace

Transcription

1 Hazards in the Workplace Fact Sheet: Confined spaces Confined spaces are a major hazard to workers who are required to work within these areas. Confined spaces include, but are not limited to, storage tanks, process vessels, pits, vats, vaults, sewage digesters, sewer silo, tunnels, manholes, utility vaults, pumping stations, enclosed grit chambers or similar types of enclosure with limited access and without proper ventilation. Entry into confined spaces may be for the purpose of inspection, testing of equipment, maintenance (repair and cleaning) or an emergency. Chapter 2 of the NSW OHS Regulations 2001:Places of work risk management and other matters imposes obligations on an employer to identify foreseeable hazards that may arise from the conduct of the employer s undertaking. It is an employers responsibility to assess the risks of those hazards and to eliminate the risks or, if not reasonably practicable to do so, to control the risks. Chapter 4 part 4.3 Division 9 of the NSW OHS Regulations specifically defines what control measures must be taken prior to entering a confined space. What is a confined space A confined space means an enclosed or partially enclosed space that: Is not intended or designed primarily as a place of work. Is at atmospheric pressure while persons are in it. 1

2 May have an atmosphere with potentially harmful contaminants, an unsafe level of oxygen, or stored substances that may cause engulfment. May (but not need) have restricted means of entry and exit. Confined spaces are normally entered to perform necessary industrial tasks. The list below represents some typical reasons for entering confined spaces. Cleaning to remove waste or sludge Physical inspection of plant or equipment Installing pumps, motors or other equipment Maintenance work painting, sand blasting or applying surface coatings Reading of meters, gauges or dials Repair work (e.g. welding or cutting) Installing, repairing or inspecting cables (e.g. telephone, electrical or fibre optic) Tapping, coating or testing of piping systems (e.g. steam, water or sewage) Constructing a confined space (e.g. industrial boiler) Rescuing people who are injured or overcome by fumes 2

3 You need to check if the work can be done another way so that entry or work in confined spaces is avoided. Better work planning or a different approach can reduce the need for confined space working. Ask yourself if the intended work is really necessary, or could you: Modify the confined space itself so that entry is not necessary; Can the work be done from outside, for example: Blockages can be cleared in silos by use of remotely operated rotating flail devices, vibrators or air purgers; Inspection, sampling and cleaning operations can often be done from outside the space using appropriate equipment and tools; remote cameras can be used for internal inspection of vessels. 3

4 Examples of confined space hazards Confined spaces are particularly dangerous because the hazards may not be immediately apparent. The dangers of confined spaces can include: Biological hazards, such as bacteria Exhaust gases Flammable gases Low oxygen levels Noise Extremes of temperatures Falling objects from height Slips, trips and falls Manual handling Electricity Radiation Poor access/egress Visibility Hot work within the space. Engulfment Entrapment Risk of engulfment if stored substances collapse Toxic gases Solids, such as wheat. TRAINING Proper training, careful preparation and good judgment are essential to safe confined space entry. The employer is required to provide initial and refresher 4

5 training to equip employees with the understanding, skills and knowledge necessary to perform the confined space entry safely. Training MUST be provided to each affected worker before performing assigned duties in confined spaces. Entrants, attendants, supervisors and rescuers require different levels of training according to their specific duties and responsibilities. Identifying Hazards and Assessing The Risk The NSW Occupational Health and Safety Act 2000 requires employers (or persons in control of the place of work) to: 1. Identify the hazards associated with working in the confined space. 2. Assess the risks (i.e. determine if the hazards are significant). 3. Control the risks by: Elimination; Substitution; Isolation; Engineering controls; Administrative controls; and Use of personal protective equipment. The Act gives detailed information on hazard identification and risk assessment. Some of the things that should be considered include: Oxygen-deficient atmospheres, which can cause brain damage and death. Oxygen deficiency can be caused by rust, fire, absorption by grain or soils, consumption by bacteria, and displacement by another gas. 5

6 Toxic atmospheres, containing gases, vapours, dusts or fumes that have poisonous effects on the body. Cleaning, painting or welding may produce dangerous vapours or fumes. A flammable or explosive atmosphere, containing flammable gases, vapours or dusts which could be ignited by a spark or open flame. The risk of explosion or spontaneous combustion is increased if an oxygenenriched atmosphere exists (where the oxygen content is greater than 23.5%). Engulfment results when a substance, liquid, or solid flows around a person and encloses them, hindering their ability to escape and often making it impossible for them to breathe because they become immersed in the substance. A sudden release of water into a confined space might cause engulfment. A sudden release of sawdust, sand, or grain may also cause engulfment. Entrapment can occur in any space that has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section. Engulfment and entrapment are serious health and safety hazards that require the highest level of standby services, specific controls such as lifelines, and an entry permit. Operation of moving parts, e.g. being trapped or crushed by augers, mixers, agitators or conveyor belts). Uncontrolled introduction of steam, water, or other gas or liquid. 6

7 Control Measures Preventing injury and death in the workplace requires identifying confined spaces and the type of work performed inside them. Your Union can offer information and advice. To reduce the risks: Whenever possible, eliminate the need for anyone to go inside the confined space - for example, use mechanical aids instead. Find out what is in the confined space before planning entry. Assess the air in the confined space. This should be done if you don t know for certain what s been in there in the past. Do not assume it is safe. Devise safety procedures for working inside the confined space. Make sure that any cleaning compounds or equipment used in the confined space are properly assessed. Make sure anyone going into a confined space has appropriate protection. Devise emergency and rescue procedures. Rehearse emergency and rescue procedures regularly. Thoroughly train the people who work inside the confined space. Monitoring for atmospheric hazards Air monitoring must be conducted before entry to determine if acceptable entry conditions exist in the space. It may be possible to increase the number of openings and therefore improve ventilation. Once the initial monitoring is completed, the monitor should then be carried by the entrant into the confined space. It is important to monitor at the top, middle and bottom of each permit space. Some gases, such as methane, are lighter than air and will tend to be present near the top of the space. Other gases, such as carbon 7

8 monoxide, are the same density as air and will be found near the middle of the confined space. Still other gases, like hydrogen sulphide, are much heavier than air and will tend to be present near the bottom of the confined space. If testing reveals an oxygen deficiency or an oxygen-enriched atmosphere, the presence of flammable gases or the presence of toxic gases or vapours, the space must be ventilated and retested before workers may enter. If ventilation is not possible and entry is necessary, for example in emergency rescue, workers must have appropriate respiratory protection. Hazards may exist at distances far from the entry point, and new hazards may enter the system at any time. Continuous monitoring means that the person(s) entering the confined space must carry the monitoring device with them into the space. While the entrant is performing work in the space, the monitoring device continues to look for changes in oxygen content or the presence of flammable and/or toxic gases. It is important to check the monitor before you enter the space to make sure that the alarm is working properly. All monitors should have an alarm that can be heard by the entrant or attendant above background noise levels. The alarm sounds if the levels of oxygen, flammable gases or toxic gases are too high or, in the case of oxygen, if the level is too low. Most monitoring devices are also equipped with a visual alarm a light that will flash rapidly at the same time that the alarm goes off. 8

9 Signposts and permits All confined spaces should be clearly signposted. Safety regulations demand that only workers with valid entry permits may go inside a confined space. Those workers should be thoroughly trained and familiar with emergency procedures. Entry permit The entry permit is the document that certifies that the employer complies with the requirements of the standard for entries in permit-required confined spaces. An entry permit must be filled out before a worker enters a confined space (and posted at or near the confined space). It should contain the following types of specific information concerning: Identification of space; Purpose of entry; Date and duration of permit; List of authorised entrants; Name of current Confined Space attendant/safety Stand-By; The hazards of the permit space to be entered; The measures used to isolate the permit space and eliminate or control hazards; The acceptable entry conditions; The results of atmospheric monitoring; Rescue and emergency services that can be summoned and the means for summoning those services; 9

10 The communication methods used by entrants and attendants to maintain contact; Any other safety information necessary for the specific space; and/or Any additional permits, such as for hot work (welding). Ventilation The risks of confined spaces include low oxygen levels or harmful vapours. It is impossible to smell oxygen or some lethal gases, so the human nose is an unreliable indicator of safe or unsafe atmospheres. Instead, the air in confined spaces needs to be regularly tested for oxygen and contaminants using the proper equipment. Mechanical ventilation, such as fresh air blowers or extractors, should always be used. Safety suggestions include: Make sure any mechanical or other types of equipment are suitable, especially equipment being used in flammable areas, which should be non spark generating and flameproof. Make sure the ventilation system is powerful enough to be effective. Operate the ventilation system before anyone enters the confined space to make sure the atmosphere is safe. Ventilation should be operating continuously while anyone is inside the confined space. The ventilation line should be close to the working face. Any exhaust from machinery should be vented straight out of the confined space. When using vaporous chemicals such as solvents, refer to Material Safety Data Sheets (MSDS) for their safe use. 10

11 Air Monitoring equipment If a safe atmosphere can t be guaranteed, the use of appropriate safety equipment, such as air-supplied respiratory protective equipment, is paramount. If the confined space contains chemicals or dangerous substances, other protective equipment required may include gloves, goggles and overalls. It is also essential to have a GAS DETECTOR such as a Dräger, to monitor oxygen levels and any other toxic gas levels inside the confined space. Many monitors must be calibrated after every use in an environment that has similar heat and humidity conditions as the confined space. The manufacturer s recommendations should be strictly followed. Many monitoring devices must be zeroed OR bumped before each use by exposing the monitor to clean air and setting the indicator to zero. Just turning the instrument on is not enough. The indicator must be zeroed frequently in a clean environment when monitoring an area for an extended period of time. Harnesses and winches, when attached to the person entering the confined space, are an excellent backup, but they must be properly organised. Protective equipment Personal protective equipment is used to protect workers only after all other feasible means have been used to control or eliminate hazards. A full body or chest harness and a lifeline should be used when entering a confined space. In some situations, a respirator will also be needed. Air-purifying respirators can filter dangerous substances from the air, but they provide no protection in an oxygen deficient environment and should not be used when working in a confined space. Only air-supplying respirators (SAR/SCBA) should be used in confined spaces. An airline respirator can only be used if the worker has a rescue bottle. 11

12 Hardhats, safety goggles, face shields, gloves, safety shoes, boots, disposable suits, ear plugs or muffs, non-sparking flashlight and tools may also be needed when entering a confined space. Observation and communication Make sure the people inside the confined space are monitored from the outside. There should be a person trained in initiating emergency procedures observing them from a safe vantage point. Standby person The Standby Person must: Maintain visual and audible contact with those working in the Confined Space. Maintain clear access/egress to Confined Space. Initiate emergency procedures where necessary. Be responsible for administering the Confined Space Entry Permit. Not enter the Confined Space unless he/she is relieved by another standby person. Not participate in any other work duty or task while the Confined Space is occupied. If you are a confined space safety stand-by person, do not leave your post until you have arranged and handed the confined space over to your replacement, giving all details, such as who is inside and work being carried out, to your replacement. If you are a confined space safety stand-by person, under no circumstances enter a confined space if communication is lost with person inside or if an emergency occurs. Follow the emergency procedures set out in the risk assessment/safe work method statement and contact emergency services. Many people die trying to perform a rescue themselves. 12

13 Emergency procedures When things go wrong, people may be exposed to serious and immediate danger. Effective arrangements for raising the alarm and carrying out rescue operations in an emergency are essential. Contingency plans will depend on the nature of the confined space, the risks identified and consequently the likely nature of an emergency rescue. Emergency arrangements will depend on the risks. You should consider: Communications How can an emergency be communicated from inside the confined space to people outside so that rescue procedures can start? Don t forget night and shift work, weekends and times when the premises are closed, eg holidays. Also, consider what might happen and how the alarm can be raised. Rescue and resuscitation equipment Provision of suitable rescue and resuscitation equipment will depend on the likely emergencies identified. Where such equipment is provided for use by rescuers, training in correct operation is essential. Capabilities of rescuers They need to be properly trained people, sufficiently fit to carry out their task, ready at hand, and capable of using any equipment provided for rescue, eg breathing apparatus, lifelines and firefighting equipment. Rescuers also need to be protected against the cause of the emergency. Shut down It may be necessary to shut down adjacent plant before attempting emergency rescue. First aid procedures 13

14 Trained first aiders need to be available to make proper use of any necessary firstaid equipment provided. Local emergency services How are the local emergency services (eg, fire brigade) made aware of an incident? What information about the particular dangers in the confined space is given to them on their arrival? Contact WorkCover or your Union for advice and information. REFERENCES EXPOSURE STANDARDS FOR ATMOSPHERIC CONTAMINANTS IN THE OCCUPATIONAL ENVIRONMENT SAFE WORKING IN A CONFINED SPACE - AUSTRALIAN STANDARD AS (NOHSC:1009(1994)) National Code of Practice for the Control of Workplace Hazardous Substances This material was developed by Unions NSW with the assistance of The Workers Health Centre as part of a project funded under the WorkCover NSW WorkCover Assist Program. Any views expressed are not necessarily those of WorkCover NSW. 14

15 For more information please contact your union. This Fact Sheet is recommended as a guide only and is not a substitute for professional or legal advice. If you need clarification or further advice please consult your Union for further information or 15