Chapter 5 Engineering Safety
1. ELECTRICAL SAFETY
This section addresses safety precautions associated with the use of electrical equipment at HKUST.
B. Hazards of Electricity
The most common hazards created by electricity and electrical equipment are :
1. Electric Shock
Electric shock refers to current passing through the body resulting in injuries or death. This normally occurs when a person becomes part of an electric circuit by having contact with live electrical parts. The effects of electric shock are mainly a function of the magnitude of current that flows through the body. Other factors such as the voltage, type of current (AC or DC), body resistance (determined by the wetness condition of the body), the duration of current passing through the body and the part of the body through which the current passes, will determine the severity of the shock. Current as low as 50 mA can cause serious injuries or even death. As little as 100 mA of current can cause heart fibrillation when the current is passing through the heart. Electric shock can also cause rapid involuntary muscular contraction which leads to other hazards such as falling when a person is bounced away from a source of electric shock.
2. Heat, fire and explosion
When current flowing through conductors exceeds their designed capacity, excessive heat will be generated which may ignite surrounding materials. Arcing produced from a poor electrical contact may also ignite nearby combustible materials causing fire. Arcing and sparks occurring in the presence of an atmosphere containing combustible dust or flammable vapours may cause explosion.
3. Other Associated Hazards
These include mechanical-type (moving parts) hazards associated with working with electrical equipment such as electric drills, electric saws, grinding machines etc.
C. Relevant Legal Requirements
Electricity Ordinance (Cap. 406)
Electricity (Wiring) Regulations
Stipulate requirements and standards on wiring of fixed electrical installations; requirements on inspections, testing and certification.
Electricity (Registration) Regulations
Stipulate requirements and procedures for registering electrical workers and electrical contractors.
Electrical Products (Safety) Regulations
Stipulate requirements and standards to ensure the safety of electrical products designed for domestic use, covering plugs and adaptors.
Electricity Supply Lines (Protection) Regulations
Stipulate requirements and procedures to protect electricity supply lines so as to prevent occurrence of electrical accidents and interruptions to power supply.
D. General Safety Requirements
- All electrical installations at HKUST should be of appropriate design and construction and properly maintained in accordance with the requirements stipulated in the applicable legislation and relevant safety standards so as to prevent the danger of fire and explosion; and electric shocks to people.
- All electrical installation and maintenance works must be carried out by qualified electricians.
- When purchasing electrical equipment, including plugs, adaptors, extension boards etc., be sure that the equipment complies with the appropriate safety standards. Users should consult HSEO or DMSF if they are not sure about the appropriate safety standards.
E. Conductors and Cables
- Conductors and cables to be used should have sufficient current-carrying capacity and be adequately insulated.
- All flexible cables should be maintained in good condition.
- Flexible cables should not be joined by adhesive tapes and other means that would reduce the insulation capacity of the cables.
- Heavy rubber-insulated flexible cables should be used for apparatus which may be subjected to rough handling or moisture.
- Only conductors built to withstand rough treatment (heavy duty conductors) should be laid on the ground and, if necessary, they should be protected against damage from vehicles, mechanical equipment, rough handling etc.
- Power cables should not trail across passageways to avoid creating tripping hazards. If this is unavoidable, low profile hard rubber covers with moulded channels or other suitable protective means should be used to minimize tripping hazards and to protect the cable from damage.
- Flexible cables should not be left lying on surfaces that are oily or wet.
- The use of cable drums should be avoided due to the higher risk of cable overheating inside the drum. If it has to be used, the cable should be completely unwound from the drum unless the safe current and time limits specified by the manufacturer are strictly followed. The cable should also be fully unwound for inspections periodically.
- Flexible cables for hand-held or portable apparatus should:
- contain an earthing conductor if the fed apparatus is protected by earthing;
- be relieved from mechanical strain at connections to terminals by proper use of cable clips in the plugs.
F. Electrical Connections
- All electrical equipment and installations must be properly connected to the power source by using appropriate types of plugs and sockets, or other suitable means.
- The use of extension boards should be avoided as far as practicable. When their use is unavoidable, they should be of safe and approved types. A single extension cable must be used for the purpose. The use of several extension boards to make up a long extension board is prohibited.
- Extension boards should be placed clear of the floor to prevent them from being affected by floods.
- The use of adaptors is not recommended. An extension board is preferred for providing additional socket outlets when permanent ones cannot be practicably provided. A power plug should be pulled out from the socket by holding the plug instead of the flexible cable.
G. Safe Use of transportable and portable electrical equipment
- Except for double-insulated electrical tools, all other electrical tools must be protected from electricity leakage by proper earthing.
- Hand-held electrical tools should be of such design that when the tool is released by the user, the power supplying the tool will be cut off automatically .
- Electrical tools used in flammable or explosive atmospheres must be of an approved flame-proof design.
- Avoid using electrical tools in wet areas.
H. Grounding And Bonding
- All exposed non-current-carrying metal parts which are liable to become energized must be grounded. These should include:
- Metallic enclosure of current-using equipment, other than double insulated equipment;
- Metallic conduit, trunking and ducting for enclosure of cable(s);
- Metallic enclosures of current distribution equipment such as switchgear and control gear assemblies.
- Metallic work surfaces.
- All necessary grounding and bonding should be installed according to the Electricity (Wiring) Regulations and other applicable standards.
I. Inspection and Maintenance
- Before each use, electrical equipment and tools should be inspected for signs of damages and defects, e.g., of the casing or flexible cable.
- Any defects found on an electrical equipment must be immediately reported to the responsible person. Such equipment must be properly labeled to avoid being used unknowingly by other people.
- All electrical equipment should be regularly inspected and maintained in accordance with the manufacturer's instructions and should conform to an appropriate inspection and maintenance schedule determined by unit management.
- Proper records of inspections and maintenance of electrical equipment should be kept by unit management.
- All repairs for electrical equipment must only be carried out by qualified electricians.
- Electrical repair and maintenance should be conducted after the power supply to the installation or equipment has been properly disconnected. “Live” electrical work should be discouraged. When “live” electrical work is inevitable, it must be conducted by personnel qualified for such work and all necessary precautions must be taken.
- Approved insulated tools must be used when work is being carried out on or near live electrical parts.
J. Discharge of Capacitors
- Capacitors are potentially hazardous due to their ability to store electric charges. A discharge of energy exceeding 10 joules into the human body can be lethal, while 0.25 joule will give a heavy shock.
- Capacitors built into equipment should be isolated with barriers or enclosures to prevent contact with charged terminals. Interlocking devices may be needed for some systems to ensure that personnel cannot gain access to hazardous capacitors until they are effectively discharged and grounded. Warning signs stating the hazards and precautions should be posted.
- When shutting down equipment for maintenance and repairs, provisions should be made to effectively and safely discharge capacitors capable of storing more than 0.1 joule . High energy capacitors should be physically grounded regardless of the existence of bleeder resistors, dump switches, interlocks, or other potential de-energizing devices.
- All high grade capacitors, if left on an open circuit after discharge, will recover a considerable proportion of the original charging energy which may still cause serious or even lethal electric shocks. Therefore:
- Each spare or disconnected capacitor, when not in use, should be kept short-circuited individually by a robust connection.
- Capacitors built into equipment which is not current in use should also be short-circuited individually.
- New capacitors should also be kept short-circuited when being stored since they may have been previously energized for test purposes.
- It is highly recommended that all discharged capacitors carry a label with wordings such as “WARNING: Keep short-circuited when not in use”
- Capacitors also pose mechanical, chemical and fire hazards. A faulty capacitor in a capacitor bank may rupture, sometimes explosively. Depending on the type of dielectric used, the rupture could lead to a fire or release toxic gases. Safety measures should be implemented to control these hazards, such as provision of special fire-suppression and ventilation systems, proper shielding and enclosure etc.
K. Electrical Lockout and Tagout
The unexpected activation of equipment due to intentional but improper or unintentional and inadvertent connection of electricity supply (e.g. closing of a switch) may result in serious injuries from electrical shock or from mechanical, chemical, or thermal effects. Therefore, when working on systems which could accidentally be activated, an effective lockout and tagout procedure should be established and strictly followed. This is especially necessary when the power disconnect point is remote from the work area or when more than one person is working on the same system.
The lockout/tagout procedure should consist of the following major steps:
a) Alert the operator and other users of the system that is to be shut down.
b) Plan the shut down to ensure that the power supply to the system is effectively disconnected. It is possible that a system can have more than one source of power supply so it is important to ensure that all sources are identified and disconnected. Modification may be needed for some power disconnects to make them lockable.
c) Have all personnel (if more than on person working on the system) place their padlocks on the necessary disconnect points (lock OPEN). A multiple locking device has to be used for accommodating more than one padlock. The padlocks should be carefully selected to ensure that the keys are not interchangeable. A warning tag should also be attached with a padlock.
d) Test the “locked open” circuit to ensure that the power supply to the system has really been cut off. This is a very important step because it is possible that the wrong power disconnect has been locked open or there may be a fault inside the power disconnect.
e) When the system is resumed, have each person remove his/her padlock and tag only.
f) Before energizing the system, check once more to make sure that no one is working on the system and there is no obvious unusual condition in the system.
L. Emergency Response For Electric Shock
Prompt actions are essential for saving electric shock victims. However, extreme care must be exercised by the rescuer to ensure his/her own safety before attempting rescue actions:
- The first response is to disconnect the source of electricity if the victim is still in (or suspected to be in) contact with any live wire or equipment. In cases when the electricity source cannot be conveniently disconnected and if it is in low voltage (<220V) condition, break the contact of the victim with electrically insulated materials such as a dry timber stick, rubber hose or dry rope etc. Send someone to call the Security Control Centre for assistance.
- When the victim is clear from the electricity source and if he/she is unconscious, check if the victim is breathing and the heart is beating. If not, start Cardio Pulmonary Resuscitation (CPR) treatment if you are competent to do so. You should seek assistance from the Security Control Centre if you are not competent to perform CPR yourself. As time is critical for the rescue, decisions on the proper actions need to be made promptly.
- Electric shock victims will also likely suffer from serious burns, especially at points of contact with live electrical parts. Therefore, treatment of burns is also needed for electric shock victims.
- Electric shock victims should be sent to the clinic or hospital for examination and treatment after the application of necessary first aid treatment.
- Electricians or people who have to work with electrical installations or equipment constantly should be trained in first aid treatments (including CPR) so as to ensure the availability of competent help for shock and burn injuries.
2. WORKSHOP SAFETY
Workshops are potentially dangerous job sites in which various kinds of machineries are being used. The purpose of this section is to set out general safety rules and guidance applicable to typical workshops at HKUST. It is essential that these rules and guidance are followed in order to prevent accidents.
It is not possible for this section to cover every conceivable situation and therefore staff who have management or supervisory responsibilities must also establish and enforce safety rules to cover specific hazards in their workshops.
B. Relevant Legal Requirements
Although HKUST does not fall under the jurisdiction of the Factories and Industrial Undertakings Ordinance, the safety requirements stipulated in the following regulations under the Ordinance should be referenced :
Factories and Industrial Undertakings (Guarding and Operation of Machinery) Regulations
Stipulate safety requirements on guarding and operation of machines.
Factories and Industrial Undertakings (Woodworking Machinery) Regulations
Stipulate safety requirements on operation and guarding of various kinds of woodworking machineries.
Factories and Industrial Undertakings (Abrasive Wheels) Regulations
Stipulate safety requirements specifically for operating abrasive wheels.
C. Workshop Safety Rules
- Workshop safety rules must be read, understood and followed by workshop users.
- Specific safety rules and operating instructions consistent with the manufacturers’ recommendations should be prominently posted in the workshop close to the respective machines or processes.
- Users of machines must be properly trained. They must be fully instructed of the dangers that can arise in the use of the machine and the precautions to be observed. Inexperience operators such as students must be properly supervised.
- Staff and students should not work alone in workshops if they need to operate potentially dangerous machinery or engage in potentially dangerous work processes.
- Machines must not be used without appropriate guards. All guards must be correctly placed before a machine is started. The details on machine guarding are described in the Appendix 5A to this section. The workshop supervisor in-charge must be informed of any missing or damaged guards.
- All machines must be equipped with an efficient starting and stopping device. The device should be so located that it can be readily and conveniently accessed.
- Machinery driven by 2 or more motors with separate push button controls shall be equipped with one or more over-ride stopping devices.
- Machines must be used only within their designed capacity. No accessories larger than those recommended by the manufacturers should be used.
- Machines must NOT be allowed to be left running unattended except in special circumstances where adequate safety measures are in place and only with the written approval of the supervisor/person in charge of the workshop.
- Proper protective equipment must be used by the operator when working at a machine.
- Gloves, watches, rings, bracelets, or other jewelry must NOT be worn while operating machines.
- Machines must be isolated electrically before any repair and maintenance work such as oiling, cleaning, adjusting or removing of jammed work piece is carried out on the machine. Such isolation should be achieved by proper lockout/tagout procedure as necessary.
- Electrical connections to switch boxes, fuse boxes, isolators, etc. must only be undertaken by competent electricians qualified and authorized to perform the job.
- All conducting surfaces of machines must be grounded properly.
- A notice indicating proper first aid treatment for electric shock victims should be fixed in a prominent place in all workshops.
- NEVER use rags or other loose materials adjacent to moving machine parts.
- NEVER attempt to caliper or gauge a work piece while the machine is in operation.
- NEVER use your hands or any other objects to stop the moving parts of a machine.
- Chips should be cleaned up with a brush, not with your bare hands or compressed air.
- Oily rags or waste should be disposed of in a metal container fitted with a lid. Such container should be emptied frequently.
- The floor area around machines should be maintained in good and level condition, and be free of loose material or slippery substances. Accumulation of rubbish must not be allowed. Spills on the floor must be cleaned, or cordoned and then cleaned, as soon as possible.
- Machines should be sufficiently spaced out in a workshop to minimize hazards caused by over-congestion.
- Adequate lighting should be provided for working with machines. Artificial lighting should be placed or shaded in ways to prevent direct rays of light from impinging on the eyes of the operators during operation of the machines.
- Skin contact with cutting fluids, lubricating oils and cleaning fluids should be avoided to prevent the development of skin diseases. As some cutting fluid compounds contain toxic solvents, use of these materials should be avoided whenever possible and manufacturer’s instructions for proper use must always be followed.
- Work clothes should be washed frequently.
- Eating, drinking and smoking are not allowed in workshops. Wash hands thoroughly before leaving the workshop for meals.
- The chuck wrench or key must always be removed from the chuck immediately after use.
- An effective chuck guard should be used when the lathe is operated.
- Do not directly hold any tools with your hands. All tools should be securely fixed on proper tool holders.
- Swarf should not be allowed to accumulate in the lathe tray. Swarf must not be removed from the cutting tool by hand. A suitable brush should be used and only AFTER the rotating or moving parts stop and are stationary.
- Production of long lengths of swarf should be avoided. A special tool should be used to handle long lengths of swarf which may be produced when machining certain metals such as stainless steel.
- A stock bar projecting beyond the headstock must be guarded throughout its entire length.
- Tools and loose parts must not be left lying on the machine. They should be properly stored.
- Drilling machines should not be used without an effective guard covering the drill chuck and/or spindle.
- All gear mechanisms must be properly guarded.
- The chuck key must always be removed from the chuck immediately after its use.
- The work piece should be held in a proper tool clamp. Do not use your hands to hold the work piece.
- Swarf must not be removed by hand. A suitable brush should be used instead after the spindle has stopped rotating.
- Abrasive wheels must be properly guarded and shielded when used. The standard of guarding and shielding must comply with the Factories and Industrial Undertakings (Abrasive Wheels) Regulation.
- Abrasive wheels must be changed, dressed, examined or tested ONLY by a competent person authorized by the workshop manager. The name of competent persons authorized should be posted close to the abrasive wheel.
- The spindle speeds must be indicated on the machine. Abrasive wheels must be marked with their specific maximum speeds and they must not be exceeded.
- The tool rest must be properly set according to the standard stipulated in the Regulation mentioned in (1) above.
- A double headed abrasive wheel must not be used by two persons simultaneously.
- The blade must be guarded as much as possible.
- Adjustment must not be made while the machine is in motion.
- Guide rollers must be properly set.
- Tension and tracking of the blade must be checked before each use.
- A pusher must be used when feeding the work piece to the saw.
- The work table should be kept clean.
- The saw blade, guards and riving knife must be properly set according to the Factories and Industrial Undertakings (Woodworking Machinery) Regulations.
- A push stick or push block must be used when feeding the work piece to the saw.
- An extension table must be used for long lengths of material.
Other Woodworking Machineries
- All other woodworking machineries must be operated and guarded in accordance with the Factories and Industrial Undertakings (Woodworking Machinery) Regulations.
3. MATERIALS HANDLING
Materials handling involves lifting, moving and placing of objects. It can be done manually (manual material handling) or with the aid of equipment (mechanical material handling) such as trolleys, forklift trucks, chain blocks, etc.
This section covers manual handling operations, the proper use of common materials handling equipment, and the safe storing and stacking of materials.
B. Manual Material Handling
Manual handling operations include the lifting, lowering, pushing, pulling, carrying or moving a load by one or more persons. Accidents related to manual material handling can result in a variety of injuries such as crushed fingers, broken toes, cuts and bruises to the legs and feet, muscle strains, sprained backs, etc. However, back injuries are by far the most serious and most common problem associated with manual material handling operations.
Back injuries are not limited to industrial or construction activities, but are widespread among many work environments, including offices.
2. Relevant Legal Requirements
The Occupational Safety and Health Regulations set out specific requirements for activities involving manual handling operations. Details of the requirements are explained here.
3. Causes of Injuries
- Manual handling injuries can be attributed to a number of factors, including improper handling techniques, poor job design, as well as the physical condition of individuals.
- A bio-mechanical analysis of lifting reveals that when a person lifts and carries an object, the load must be counteracted by the back muscles. The spine is the fulcrum and the back muscles are in a fixed, short distance from the spine (Figure in Appendix 5B of this chapter). The load in front of the body is much farther away from the spine, at minimum nearly the thickness of the trunk. The farther the load is held away from the body, the greater is the “moment”, and this “moment” must be counterbalanced by the back muscles (which are having much shorter moment arms). These back muscles can easily be injured when they are stressed beyond their limits. Bending over to raise a load creates an even greater “moment”. Excessive bending may also create excessive stress on the intervertebral discs, which may cause a serious back injury called “slipped disc”.
- The vertical distance of a lift can also increase the potential for injury. Lifting overhead involves the use of other muscle groups that are seldom used. These muscles normally have less capacity and hence may be injured more easily. Reaching while picking up or putting down an object is likely to result in dropping the load and producing greater moments.
- The weight of an object being lifted is an important attribute for causing injuries. However, it is difficult to determine the maximum loading a person can safely lift due to the variability in individual strength, body dimensions, etc
- The frequency of lift is also important. The need for lifting loads repetitively may cause the physical capacity of an individual to be exceeded easily, which may lead to fatigue, error and injury.
- Lifting heavy loads with one hand or twisting during a lift increases the likelihood of injury because the human body is not well suited to asymmetrical loads or rotation.
4. Control Measures
The potential for injury caused by manual material handling should be minimized by applying both administrative and engineering control measures.
a. Administrative Controls
These refer mainly to issues such as assessment of lifting tasks, training, provision of personal protection equipment, and proper job assignment.
Risk assessments should be conducted to identify lifting tasks which may pose significant risk of injury to employees. It is in fact a requirement by the law for conducting such risk assessments. The provision of proper training is very important in reducing injuries resulting from manual material handling. Training should include the recognition of dangers in manual material handling, and use of proper lifting practices to avoid unnecessary stress to the body. Some recommended good practices in manual lifting are contained in Appendix 5C of this section. Management is responsible for ensuring that employees are properly trained to perform assignments safely. Assistance is available from HSEO in conducting training on material handling and how to conduct risk assessments.
To avoid physical injuries such as punctures, crushes, lacerations, etc., appropriate protective equipment such as gloves, safety shoes, work clothes and/or safety helmets should be provided to and used by workers performing heavy manual materials handling operations. Management is responsible for ensuring that workers properly use the protective equipment provided to them.
Management is also responsible for ensuring that employees are physically capable of performing the tasks assigned to them.
b. Engineering Controls
Engineering controls refer to measures including:
- Deployment of appropriate mechanical aids such as use of mechanical lifting devices, trolleys, forklift trucks, etc. for moving and handling heavy objects.
- Improvement on visual and thermal environments such as lighting, colour, labeling etc.
- Proper workstation design so that workers can adopt best working postures without the need for excessive bending and over-reaching.
C. Mechanical Materials Handling
1. Forklift Trucks
Forklift trucks are commonly used for moving and stacking goods on pallets. Forklift trucks can be powered by different kinds of fuels such as LPG, batteries and diesel.
Forklift trucks differ from ordinary road vehicles in that they are operated with rear wheel steering. As a result, both the forks and the rear of the vehicle swing wide on corners. Forklift truck drivers have to be trained and need sufficient practice before they can adjust to the difference.
The major hazards involving forklift trucks include collision with other trucks or a structure, knocking down persons, overturning of truck, falling of goods, etc.
There are some basic steps for forklift truck safety:
- Proper Training and Authorization
Only fully trained, authorized drivers are allowed to operate forklift trucks. A license for driving ordinary road vehicles cannot substitute the need for proper training and authorization in operating forklift trucks. Unit management is responsible for authorizing qualified employees to operate forklifts on campus. HSEO is available to assist in organizing necessary safety training.
- Knowledge of the Job
The forklift truck operator should know the scope and type of the job before starting the operation.
- Observance of Rules and Instructions
The operator should be familiar with the forklift truck he is operating and operating instructions specified by the manufacturer of the truck. The operator should also follow all other applicable safety rules when operating the forklift truck.
- Proper Maintenance and Checks
Forklift trucks should be properly maintained according to a routine schedule. Appropriate pre-start checks should be performed as specified by the manufacturer.
2. Lifting Equipment and Lifting Gears
There are many kinds of lifting equipment such as cranes, hoists, winches, chain blocks, etc. which are used for moving materials vertically and horizontally. Lifting equipment also includes lifting gear such as chains, slings, shackles, eye-bolts, etc.
Hazards associated with the use of lifting equipment include:
- falling of elevated materials due to improper fixing, tying, slinging, etc.,
- structural failure of lifting equipment due to overloading,
- overturning of mobile cranes due to improper operations,
- striking of persons or objects by the lifting equipment or by the loads being lifted as a result of inadequate visibility of the operator, etc.
Proper setup and planning. This includes placing of the lifting equipment on a level site, staying away from power lines and proper assembly of the equipment including its boom, jib and other elements.
All lifting equipment should be inspected, examined and tested with reference to the appropriate local legislation, i.e. the Factories and Industrial Undertakings (Lifting Appliances and Lifting Gears) Regulations and the Construction Sites (Safety) Regulations.
Persons operating lifting equipment should be adequately trained in the operation of the equipment and in the proper procedures for safe lifting. Other persons (such as slingers, signalers etc.) involved in lifting operations should also be properly trained.
D. Storage and Stacking of Materials
Common hazards associated with storage and stacking of materials include:
- Falling of items on people below them.
- Tripping over or striking against items protruding into traffic ways or aisles,
- Fire and explosion resulting from storage of incompatible chemicals.
- Materials damage caused by improper use of material handling equipment
Materials and objects should be properly stacked to prevent breaking, falling, tipping and rolling. Boxed materials can be stacked up to a certain height depending on the strength of the package or the material. Over-stacking may cause damage to materials on lower layers and as a result, the whole pile may tip over or material breakage and/or leakage may occur. Stacking techniques such as cross tying of materials, interlocking and stepping back materials can improve the stability of material stacks.
No person should be allowed to climb directly on stacks. Safe means for accessing stacks, such as ladders, should be used for getting access to the top of the stacks. If someone has to move to and fro regularly along the top of stacks, walkways and bridges protected by guard-rails built on top of the stacks may be considered.
Materials should not be placed or stacked near the edge of any excavation, shaft, pit or other opening on the ground or floor.
Before stacking or un-stacking operations are carried out, the surrounding areas should be clear of obstacles, oil and grease, etc that may present hazards. Stacks should only be taken down from the top, and objects should NEVER be pulled out from under.
Inspection of stacks should be conducted on a regular basis. Unstable stacks, and stacks showing signs of breakage or leakage should be taken down promptly and carefully.
4. WORKING AT HEIGHT
People falling from height can result in very serious and fatal accidents. Management must make every effort to prevent this type of accidents.
Working at heights may involve works to be carried out on the surfaces of a structure, on temporary working platforms, ladders, gondolas, etc. This section sets forth the safety precautions required to safeguard people from falling from heights.
B. Elevated Workplaces
- All elevated workplaces from which a person is liable to fall shall be securely fenced to a height of 900mm.
- Elevated workplaces shall be provided with safe means of access and egress such as suitable stairs, ramps or ladders.
- If it is impractical to provide appropriate fences, the persons employed at the elevated workplaces should be protected from falling by means of appropriate safety belts with lifelines or lanyards properly attached to secured points.
C. Temporary Platforms
Commonly used temporary working platforms are constructed with steel tubes. The working platforms can be “static” in the form of a tower (normally called tower scaffolds), or “mobile” with rolling castors fitted at the base. Reference should be made to the relevant codes of practice published by the Hong Kong Labour Department for details on the design and construction of scaffolds. Without prejudice to the aforementioned codes and other applicable legal requirements, the following safety measures should be observed:
- The decking of a working platform should be closely boarded, planked or plated. If the platform consists of interstices, none of them should exceed 3,800 square millimetres in area.
- The decking of the working platform should be of sound construction, adequate strength and free from defect. The thickness of the decking materials should be capable of supporting the loads on top safely having regard to the span between the supports. As a general guidance, the width of a timber board should not be less than 200 mm and the thickness should not be less than 25 mm.
- The boards or planks forming the surface of the working platform should not overhang beyond their supports to a distance more than 150 mm unless they are adequately secured to avoid tipping.
- Working platforms from which a person is liable to fall a distance of more than 2 metres should be protected on all open sides with proper guardrails and toe-boards of not less than 200mm.
- Proprietary types of tubular scaffolds that are used as working platforms should be erected in strict accordance with the manufacturer's erection guides.
- Proper access should be provided for reaching working platforms by means of ladders or stairs. Sloping stairs fitted inside the tubular scaffold tower should be preferred over vertical ladders for accessing working platforms. If vertical ladders are to be used, they should be fitted on the inside of the narrowest side of the tower so that the person climbing the ladder is inside the scaffolds. The frame members of a tower scaffold should not be used as access unless it has built-in ladder sections with rungs not more than 300 mm apart and stiles not more than 480 mm apart.
- As a general safety rule, the height of a tower scaffold should not exceed the narrowest side of its base by 3 times in normal situation. In windy situation, this ratio should be reduced accordingly. If this ratio has to be increased, outriggers should be fitted to widen up the base or the tower scaffold must be securely attached to the nearby structure.
- It is extremely dangerous and therefore strictly forbidden to use ladders, boxes, stools, etc. on the platform of a tower scaffold to extend its height. Tower scaffolds and other working platforms must be erected on a firm and level base. They should not be erected on newly made up ground, timber spanning an excavation, etc.
- The castors of a mobile tower scaffold or working platform must be securely locked at all times except when it is being moved.
- Before attempting to move a mobile scaffold or working platform, the ground condition should be checked to ensure that there is no obstruction or hole in the ground. The surface should be firm and level. No persons or materials are allowed to stay on the platform when it is being moved.
- All temporary working platforms should be inspected regularly to ensure that they are safe for use. Any damages or defects discovered must be reported and repaired immediately, or the working platform must be removed from service. Warning signs must be posted prominently on damaged or incomplete working platforms.
D. Bamboo Scaffolds
Bamboo scaffolds are commonly used for providing working platforms for working at heights, especially for construction works. Reference should be made to the relevant codes of practice published by the Hong Kong Labour Department for detailed safety provisions for bamboo scaffolds. Provisions stipulated in the codes and other applicable legal requirements must be strictly followed.
Ladder is a common and convenient piece of equipment for reaching heights. However, serious accidents may occur when ladders are used improperly. The following are essential safety guidelines to follow:
Design and Construction of Ladders
- Wooden ladders should be constructed with:
- stiles of adequate strength made of wood free from visible defects and having the grain of the wood running lengthwise; and
- rungs made of wood free from visible defects and mortised or rabbetted into the uprights.
- The support for the rungs must not depend solely on nails, spikes, screws or other similar fixing.
- Uprights and rungs of metal ladders should have a cross-section adequate to prevent excessive deflection.
- The intervals between rungs should be equal, and not be less than 250 mm or more than 350 mm.
- The rungs of metal ladders should be corrugated or treated to prevent slipping.
Safe Use of Ladders
- The ladder being used should be of a type suitable for the purpose (e.g. length, materials, etc.).
- Prior to use, ladders should be visually inspected for splits, cracks, missing parts and other defects to ensure that they are safe for use. Defective ladders must not be used.
- The stiles should be set on a firm base with both stiles securely supported. A ladder should not be placed against a window frame unless the ladder is fitted with a board at the top so that the applied load is safely distributed over the frame.
- Ladders should rest on firm bases. Bricks, boxes or other loose objects must not be used to level up stiles or to gain additional height for ladders.
- Adequate means should be provided to prevent the displacement of a ladder set up in a public thoroughfare or in any other places where persons, vehicles, etc. may accidentally collide with it. A ladder should not be placed in front of a door, especially one that opens towards it, unless the door is fastened open or is locked or guarded.
- Ladders should be secured at the top using lashing to stiles, and/or at ground level using suitable stakes lashed to stiles.
- A person should be stationed at the base of the ladder in locations where pedestrian or vehicular movements are frequent or when securing of top or bottom is not possible.
- A ladder should be set at an angle of approximately 75o (ratio of 1 out to 4 up) to avoid slipping or tipping backward.
- A ladder should extend at least 1 metre above the landing place so that the extending portion can be used as a safe hand hold. The working position on a ladder should always be no less than 1 metre from the top of the ladder. This 1 meter portion of the ladder is meant for use as hand hold.
- When working on a ladder, the thighs of the person must be kept between the stiles. Over-reaching off a ladder is very dangerous and must be avoided.
- Only one person is allowed on a ladder at any one time.
- Always face the ladder when ascending and descending.
- When ascending or descending a ladder, the hands of the person should be free of any tools or objects. If objects have to be carried when climbing a ladder, suitable means such as tool bags carried with a shoulder strap or waist belt should be used for the purpose.
- The rungs of a ladder should be free from grease and mud to prevent slippage. For the same reason, the shoes of a person should be cleaned of any grease or mud before climbing up the ladder.
- When using trestle ladders, ensure that the spread between the front and back legs are restrained by appropriate means in such a way that the trestles are in a stable manner. As with straight ladders, the highest working position should be at least 1 metre below the top of the ladder.
- Metal ladders must never be used at the vicinity of exposed live electrical equipment.
- Sufficient number of persons should be assigned in erecting or moving ladders, particularly long or heavy ladders.
- Ladders should never be left in the workplace unattended.
Inspection, Maintenance and Storage of Ladders
- Ladders should be inspected at least quarterly and records of inspections and repairs should be maintained for each ladder.
- Defective ladders should be clearly labeled as pending repair and must not be stored together with ladders which are in good working condition. Defective ladders that cannot be satisfactorily repaired should be destroyed.
- Ladders should never be painted with colour paints which may conceal defects. Only clear, varnish-type coatings should be used for protection purposes.
- Ladders should be properly stored in dry and well ventilated areas. Ladders should be stored in a horizontal position properly supported clear of the ground. For long ladders over 6 metres, at least 3 points of support should be provided.
Gondolas are commonly used for cleaning or maintaining external building facades. When working with gondolas, the provisions stipulated in the Factories and Industrial Undertakings (Suspended Working Platforms) Regulations should be strictly observed. Without prejudice to the provisions in the aforementioned Regulations, the following safety precautions should be observed when working with a gondola:
- The gondola, including all wire ropes, should be of a safe design, with good constructions and sound materials, and free from defects.
- Guard-rails of one metre high and toe-boards of 200 mm high should be fixed on all four sides of the gondola. For gondolas having only 2 suspension ropes (i.e. one at each end), each suspension point must have a safety rope with an automatic safety device on it. This combination should support the platform in the event of the failure of the primary suspension mechanism.
- The gondola should be suspended from appropriate roof anchorages and fixings. The entire setup of the gondola including its suspensions system must be properly tested before use. Reference should be made to Factories and Industrial Undertakings (Suspended Working Platforms) Regulations regarding inspections, examinations and testing of the gondola.
- Gondola users and operators must be trained and certified by recognized trainers.
- Each person in the gondola must wear a suitable safety belt which is attached to an independent lifeline fixed at an appropriate anchorage. The requirement for wearing safety belts with the lanyards securely attached to independent lifelines should be indicated on a notice prominently posted on the gondola.
- Effective means of communication (e.g. walkie-talkies) should be maintained between persons on the gondola and those on the ground so that prompt assistance can be provided in case of emergencies.
- A notice in English and Chinese indicating the safe working load and the number of persons that can be carried should be prominently displayed on the gondola. Overloading is strictly forbidden.
- The gondola should be operated in such a way that it is close to the building facade.
- The gondola should rest firmly on the ground or other supports and be properly secured at the end of a work shift to prevent unauthorized use.
- Smoking is strictly forbidden on the gondola.
- Gondolas should not be used in windy conditions.
G. Boatswain’s Chairs
Boatswain’s chairs that are not power-operated must not be used.
H. Power Operated Lifting Platforms
These work platforms are often used as an alternative to ladders, scaffolds and cradles for short duration work. There are various types of power operated lifting platforms which are truck-mounted or wheeled to provide quick and easy access.
The operator of these platforms must be adequately trained and fully competent in the safe operation of the equipment. The manufacturer’s operating and safety instructions must be read carefully and strictly followed. The equipment manufacturer or supplier should be consulted if any doubts arise concerning the safe operation of the equipment.
I. Working on Fragile Roofs
Roofs or skylights made of materials such as glass and plastic are regarded as fragile roofs. These structures may not be strong enough to support a person’s weight.
- When working on or walking across fragile roofing materials, proper crawling boards must be used to spread or transfer the loads of the person and materials to the adjacent supporting structural members.
- Warning notices should be posted at all approaches to roofs constructed with fragile materials. The area under the roof where work is being carried out should be adequately barricaded to prevent pedestrian access.
- Extreme care must be taken not to damage any glass roof panels. If any glass panels are suspected to have been damaged, such conditions must be reported to the Security Control Centre for immediate barricading of the affected areas. The defect should also be reported to CMO as soon as possible.
5. USE OF TOOLS
A wide variety of hand tools and power tools are used at HKUST. Improper use of these tools can cause serious injuries.
This section sets forth the safety precautions for using manual hand tools and power driven tools.
B. General Principles in Safe Use of Tools
In order to do a job safely, proper tools have to be used in a proper manner. The safety precautions described below may not cover all types of tools in all kinds of situations. It is important that anyone unfamiliar with the tools he/she uses should ask his/her supervisor for instruction in its use. Whenever a new tool is acquired or there is a procedural change, everyone involved should make sure that he/she has the knowledge and skills on their proper use.
The following principles should be observed whenever hand tools are used:
- Select the right tools for the right job Every tool is designed for a specific purpose, (e.g. screwdrivers are for driving screws, chisels are for chiseling, etc.). A tool must be only used for performing the job it is designed for.
- Tools selected should be of proper construction and in good working condition.
- Tools should be used in the correct manner Like other machines, there should be a proper way (also the safe way) of using a certain piece of tool.
- Tools should be properly stored Improper storage of tools can result in damage of tools and subsequent injury of users, especially sharp-edged or sharp-pointed tools. Such tools should be properly secured during transport.
- Tools should be regularly inspected and properly maintained
C. Manual Hand Tools
- Hand tools should be tempered, dressed and repaired only by competent persons.
- Sharp-edged and sharp-pointed tools should not:
- be thrown from person to person;
- be used in dangerous proximity to other persons or moving machinery; or
- c. be used as props, rammers, prods or the like.
- The cutting edges of cutting tools should be kept sharp.
- Heads of hammers, wedges, chisels and other shock tools should be frequently dressed or ground to a suitable radius on the edge to prevent mushrooming or cracking.
- Hand tools should not be left lying in places where persons have to work or pass, or on scaffolds or other elevations from which they might fall on persons below.
- Only insulated or non-conducting tools should be used on or near live electrical installations if there is any risk of electrical shock.
- Only non-sparking tools should be used in the presence of explosive dusts or vapours.
- Defective tools must be taken out of service and clearly tagged while waiting for repair to avoid misuse by other people. Tool damaged beyond repair should be destroyed and discarded.
- Do not hold an object or device in the palm of one hand while pressing a screwdriver into it. Instead, place the object on a bench, table, vise or other suitable support.
- Never use a screwdriver as a makeshift punch, wedge or pry-bar.
- Never hammer on a screwdriver or grasp it with pliers for turning leverage.
- Keep a screwdriver in good repair. Check for a broken handle, bent blade, or twisted tip. A sharp, square-edged bit is less likely to slip than a dull, rounded one.
- Do not use pliers as a substitute for hammers or wrenches.
- Do not use pliers as a substitute for spanners or wrenches. Pliers tend to slip when used to turn bolts and nuts.
- Select wrenches with the appropriate size and jaws for the job.
- To avoid sudden slips, wrenches should be pulled, not pushed. Be sure to stand in a balanced position when performing the work.
- Wrench handles should not be extended by lengths of pipe or other makeshift means. Too much leverage can ruin the tool or the bolt/nut and cause injury. Penetrating oil should be used to free a frozen nut or bolt instead of using a blunt force.
- Wrenches should not be used on parts of machinery when they are moving.
- Make sure the wrench selected fits the nut properly. If it doesn’t it will damage the nut or possibly fly off. Shims should not be used with wrenches to make them fit.
- Wrenches should not be used as hammers unless specially constructed for this purpose.
- Files should be provided with properly fitted handles.
- Files should not be used as pry-bars.
- Check all hammers for defects before using. Possible defects include loose hammer heads, cracked or split handles, etc.
- Use the correct hammer for the type of work to be done. Various types and weights of hammers are designed for specific jobs and should not be used for other purposes.
- Stakes or chisels being driven with a sledge hammer should be held by tongs and not by the hand.
- When using a hammer, be sure that the swing is unobstructed. Look out for overhead interference.
- Always wear safety glasses or goggles when using chisels.
- The proper type and size of chisel should be selected for the job. Cold chisels for cutting metal should not be used for cutting timber.
- Never use chisels for prying open lids.
- Always drive chisels outward and away from your body.
- Watch for mushroomed heads on chisels. The mushroomed heads must be properly rounded off.
- Use the right type of saws for cutting different materials (e.g. timber, steel, etc.).
- All saws should be kept sharp and clean.
- When cutting, use slow, deliberate strokes. Forcing the cut can make the blade buckle and snap and/or jump out onto your hand.
- Don’t hold work pieces in your hand when using a saw. Securely place work piece in a vise or other suitable support.
- Before using a jack, make sure that it has a rating sufficient to lift and support the load. The rated load should be clearly visible and permanently marked on the casting.
- Jacks must be placed on a firm foundation or block.
Storage of Tools
When not in use, sharp tools should be kept in sheaths, shields, chests or other suitable containers. Sharp-edged and sharp-pointed hand tools should be stored so that:
- the edges and points are out of reach or are otherwise prevented from causing harm;
- they cannot fall; and
- they cannot cause danger to the person removing them.
- While being transported, the edges or points of sharp-edged or sharp-pointed hand tools should be so placed, buried or sheathed as to prevent accidents and/or injury.
- Unless adequately protected, sharp-edged and sharp-pointed tools should not be carried in pockets.
- Tools should not be held by hands when climbing ladders. Appropriate tool bag tied to the waist or with shoulder strap should be used in order to free the hands.
- Tools should not be carried in a manner that the sharp edges or the sharp points face oneself and/ or other persons.
D. Pneumatic Tools
1. Materials and Construction
- Portable pneumatic tools should be used only for the work for which they are designed.
- Operating triggers on portable pneumatic tools should be:
- so placed as to minimize the risk of accidental starting of the machine; and
- so arranged as to close the air inlet valve automatically when the pressure of the operator’s hand is removed.
- Hose and hose connections for compressed air supply to portable pneumatic tools should be:
- designed for the pressure and service for which they are intended; and
- fastened securely to the pipe outlet and equipped with a safety chain to prevent the hose from whipping in case it comes off.
- Pneumatic shock tools should be equipped with safety clips or retainers to prevent dies and tools from being accidentally expelled from the barrel.
2. Handling and Use
- The use of pneumatic tools should be restricted only to authorized persons who have been given adequate instructions and training on the proper use of such tools.
- Always disconnect the source of power and release the pressure in hose lines before any adjustments or repairs.
- Always shut off the air supply before disconnecting hose lines.
- Protect air supply lines from damage by vehicles, etc.
- Avoid laying hoses over ladders, steps, scaffolds, walkways, etc. to prevent a tripping hazard.
- Never use compressed air for blowing off swarfs, cleaning clothing or parts of the body.
E. Personal Protection
Operations such as hammering, chiseling, grinding, etc. may result in projecting loose particles. Appropriate eye protectors should be worn. Ordinary corrective lens do not provide adequate eye protection.
Operations, like grinding, can generate a large amount of harmful dusts. Appropriate respirators should be worn to prevent excessive inhalation of harmful dusts.
Power hand tools such as pneumatic grinders and hammers can produce noise high enough to cause hearing damage to the operators. Appropriate ear plugs or ear muffs should be worn.
Refer to Chapter 13 when choosing the appropriate types of personal protective equipment.
6. WELDING AND CUTTING
Welding is a common work process in industrial operations for joining metals by the application of a sufficient amount of heat. Metals can also be cut into pieces by applying similar heat processes.
There are many different types of welding and cutting processes, but the two most commonly used in industrial operations are gas welding and electric arc welding.
This section sets forth the safety precautions for gas and electric arc welding and cutting operations in the premises of HKUST.
B. Hazards Associated With Welding and Cutting Operations
The principal hazards associated with gas welding are fire, explosions, burns, eye damage, heat stress, respiratory disease and systemic poisoning. Additional hazards which may result from arc welding are electric shock, ultra-violet radiation, and ozone.
- Fires and Explosions
- When any type of welding equipment is used, the naked flame, or an electric arc, provides a source of ignition for combustible materials, flammable gases or vapours. Furthermore, mishandling of gas cylinders can lead to explosions and fires.
- Heat burns may result from metal spatter or from touching hot work pieces. The hands, arms, legs, feet and the eyes are particularly vulnerable.
- Eye Damage
- During welding operations, the eyes may be injured by sparks, spatter, slag and other foreign bodies. During gas welding, infra-red and visible light are emitted. Infra-red may dry the outer surface of the eyes which may become irritated.
- Ultra-violet (UV) radiation, to which the eyes are very sensitive, is produced during arc welding. Excessive exposure of the eyes to UV radiation may result in conjunctivitis, photo keratitis or “welder’s flash”.
- Heat Stress
- Welding operations may produce sufficient heat energy to cause heat stress problems for the welder, especially when working in poorly ventilated or confined areas.
- Respiratory Disease
- Welding processes produce toxic gases and fumes which may result in respiratory diseases.
- Hot metal vapour from the molten metals will produce fumes when the vapour is rapidly cooled and oxidized by the surrounding air. The fumes consist of a cloud of fine particulates which consist predominantly of oxides of the metal being used.
- Harmful gases may also be generated during gas welding. The principle toxic gases produced are carbon monoxide and nitrous oxide fumes. Dangerous concentration of carbon monoxide may be formed in poorly ventilated areas where combustion is incomplete.
- The high voltage arc associated with arc welding produces ozone, a gas that can irritate the respiratory system.
- Systemic Poisoning
- The fumes from galvanized metals, lead coatings, specially treated surfaces, and other toxic metals may affect not only the respiratory system, but also the rest of the body, particularly when the work is conducted for prolonged periods in poorly ventilated areas.
- Welding on parts containing residues of chlorinated solvents (e.g. chlorothene VG, a degreaser fluid) can produce phosgene, a deadly nerve gas.
C. General Safety Provisions
- Before any welding and cutting operation is carried out on HKUST premises, a Hot Work Permit must be obtained in accordance with the “Procedures for Hot Work On University Premises”. Workshop areas designated for welding operations are exempted.
- Appropriate provisions stipulated in Chapter 6 “Fire Safety” should also be observed.
- All persons involved in welding and cutting operations should be fully trained and aware of the hazards involved.
- Welding and cutting operations MUST NOT be conducted near unprotected plant and vessels which contain flammable liquids or gases. For plant and vessels containing flammable liquids, all traces of flammable contents, such as oil-impregnated scale or flammable vapour, must be removed completely before any hot work is carried out. They should not be refilled until the metal has cooled down. The same is required for other chemical storage vessels.
- A competent person should be appointed to undertake periodic maintenance, examination and repair of welding equipment.
- Sufficient ventilation should be provided when welding operations are carried out. Local exhaust ventilation should be provided when a high concentration of welding fumes is anticipated. Ventilation should be so arranged that the welding fumes are drawn away from the breathing zone of the welder.
- Articles which have just been welded should not be left unattended while they are still hot. Warning signs should be posted as appropriate.
D. Gas Welding and Cutting
In gas welding, metal fusion is achieved by the use of very high temperature flames produced by a mixture of gases at a torch or blowpipe. The gases involved are oxygen and a fuel gas, such as acetylene or LPG.
Oxygen has no smell and is not itself flammable, but it is a very good supporter for combustion. As such, excessive oxygen in the atmosphere can be extremely dangerous. Substances such as oil and grease normally do not burn without a source of ignition. However, these substances may burst into flame in the presence of a high concentration of oxygen. Oxygen level in the atmosphere should not exceed 25%.
Acetylene is highly flammable and can form an explosive mixture with air or oxygen. Storing acetylene under high pressure in its gaseous state is extremely dangerous. Therefore, acetylene is stored in solution of acetone inside the cylinder. The cylinder is also filled with a porous filler mass to ensure that there are no free spaces in which acetylene gas can be present. Acetylene should never be used or compressed in a free state at pressures higher than 15 psi, otherwise an explosion may result.
Safety of Equipment
a. Gas Cylinders
- Gas cylinders should be properly stored. They should be promptly returned to approved dangerous goods stores when not in use. Oxygen cylinders must never be stored with fuel gas cylinders.
- Cylinders should be protected against direct sunlight and heat.
- Empty cylinders should be marked as such, but they should be treated as if they are full in all other respects.
- Acetylene cylinders must always be kept in an upright position.
- Cylinders should not be allowed to stand freely. They should be properly secured by means of racks, chains, etc., to prevent them from tipping.
- Care must be taken when transporting gas cylinders. When the cylinders have to be moved frequently, they should be transported on a suitable trolley.
- If cylinders have to be handled by means of a crane, they should be secured in a special carrier before being lifted. An ordinary chain sling should not be employed directly on cylinders.
- Gas cylinders must be treated with care and be protected against mechanical damage, falls, or excessive heat.
- Cylinders must never be used to support loads.
- When not in use, cylinder heads should be protected with caps to prevent damage to the valves.
b. Regulators and Fittings
- Cylinder valves and all other connecting parts should be kept free from oil and grease.
- Cylinder valves should be firmly closed when they are left unattended for a long time (e.g., at the end of the day or a work shift).
- Valves of empty cylinders should also be closed to prevent contaminants from getting into the cylinder.
- Blow out the cylinder valves for about one second to expel any dust or debris before attaching the regulators to the cylinders.
- Only the type of regulator designed for the gas being used should be fitted to the cylinder.
- The adjustment screw of the regulators must always be released before the cylinder valve is opened, and this should be done slowly. Stand to one side of the regulator before opening the cylinder valve. The bonnet of the regulator is the weakest part which may be blown out in an accident.
- A flashback arrestor should be fitted to the regulator outlet in the acetylene line to avoid accidental flashback. A second flashback arrestor in the oxygen line will give additional safety.
- Cylinder valves should be operated by using standard keys. Long leverage spanners or keys fitted with extension pieces should not be used. Excessive force should be avoided in closing valves.
- Fittings made of copper or copper-rich alloys should not be used for acetylene gas. A dangerous explosive substance may be formed when acetylene is in contact with copper.
- The pressures of oxygen and acetylene should be the same to prevent the risk of mixing of gases inside the hoses.
- Blowpipes should be regularly checked to ensure that they are clean and in good working condition. Hose couplings, connections and valves should be inspected for leaks at the beginning of each shift.
- Repairs to blowpipes should only be done by the manufacturers or firms specializing in this type of work.
- Before lighting the blowpipe, purge the oxygen and fuel gas passages individually in order to expel foreign gases. Regulator pressure can be set while the gas is flowing.
- Light the fuel gas before opening the oxygen valve on the torch.
- Blowpipes should be lit using proper means such as a friction lighter, stationary pilot flame. Never use matches, cigarettes, or cigarette lighter for this purpose.
- Clogged blowpipe tip should be cleaned with suitable appliances designed for this purpose.
- The manufacturer’s recommended pressure for the blowpipe must never be exceeded.
- The hoses used for gas welding and cutting must comply with the appropriate standards.
- Hose lines for different gases should be of different colours. According to BS 5120, red hose should be used for acetylene and hydrogen, orange hose for propane or other LPGs, and blue hose for oxygen.
- Hoses should be securely attached to the connections by means of suitable clips.
- Supply hoses should be so arranged that they do not pose any tripping hazards, or will not be damaged by vehicles or other moving objects.
- Hoses of equal lengths should be used for oxygen and the fuel gas.
- Hoses should be of sufficient length for the necessary manoeuvring of the blowpipe. A sudden jerk or pull on the hoses may cause the blowpipe to be pulled out from the operator’s hand, cause a gas cylinder to fall over, or a hose connection to fail.
- Hoses should be inspected frequently to ensure that there are no cuts or cracks. If defects are found, the hose should be replaced without delay.
- Naked flames should never be used for leak testing. Proper leak test solution should be used.
- Compressed air should not be used to purge any hose since it may contain oil residue from the air compressor.
- Specific Hazards
A flashback is a very dangerous occurrence in gas welding which is caused by mixing and burning of the gases inside a hose. Such mixing of the gases usually occurs when the hoses have been disconnected from regulators and/or blowpipes, or when new hose is being used for the first time. Sometimes it is due to loose connections. A fire or an explosion may occur when a flashback occur.
Preventive measures for flashback:
- A flashback arrestor should be fitted at the regulator outlet in the acetylene line to avoid accidental flashback. A second flashback arrestor in the oxygen line will provide additional safety.
- Ensure all connections are tight.
- Ensure cylinder valves are open and blowpipe valves are closed.
- Set regulators to the required pressure.
- Purge each hose separately and consecutively by opening the blowpipe valve and allowing gas to flow for sufficient time to ensure that only pure gas remains in the hoses. Close the valve for each gas after the exercise is complete. This exercise should only be carried out in open air or in well ventilated areas.
b. Heated Cylinder
When an acetylene cylinder is accidentally heated or becomes hot due to internal decomposition, the following steps should be taken if safe to do so:
- Remove any external source of heat.
- Shut off valves, detach regulator and other fittings.
- Drag the cylinder to an open space and keep applying water until the cylinder becomes cool (immerse the cylinder in water if possible).
- Fully open the cylinder and keep applying water until cylinder is empty. The area should be cleared of other personnel.
- Contact the suppliers for advice and request them to remove the cylinder.
E. Electric Arc Welding and Cutting
In electric arc welding, the arc is struck between an electrode and the work pieces. The temperature attained by the welding arc is approximately 4000 oC. At this temperature, the work pieces are melted and fused together.
Safety of Equipment
- Welding Transformers
- All welding transformers should be designed, constructed, protected and maintained in a way that prevents electrical hazards.
- All exposed conductive parts of a transformer should be properly grounded.
- The primary (input) terminals of a transformer should be properly insulated and protected to prevent electrical hazards.
- The secondary (output) terminal of a transformer should be shrouded by insulating sleeves of sound construction and design.
- Routine maintenance, including insulation testing, for the arc welding and cutting equipment should be carried out regularly.
- Welding Circuit
- A proper welding return should be provided and its cross-section should not be less than that of the welding lead. The return lead should be securely bonded to the work piece.
- Bare conductors should not be used as welding leads or welding returns.
- The work piece should be effectively grounded and the conductor forming the work piece earth should be of at least 16 mm cross-section and of sufficiently low impedance. It should also be protected from mechanical damage and inadvertent disconnection.
- All cable connections should be clean and tight. Cable connectors should be used.
- All cables should be of the correct type and current-carrying capacity. They should be routinely examined for defective insulation.
- Trailing welding cables should be kept clear of walkways and be protected against mechanical damage using coverings or by securing to overhead fixture. They should be properly laid to prevent tripping hazards.
- Welding Electrode Holders
- A fully insulated electrode holder of correct rating should always be used.
- When not in use, the holder should not be placed on metal objects. It should be hung up so that it is clear of any nearby metal objects, or placed on a wooden or non-conducting surface.
- The welding cable should be properly connected to the holder.
- The electrode holder should be properly maintained to prevent damage to the insulating material.
Safety Precautions during Electric Arc Welding Operation
- Insulating gloves should be worn when an electrode is inserted into or removed from a holder.
- Welders should avoid:
- allowing any part of their body to complete an electric circuit;
- touching any electrically live parts with wet or damaged clothing, gloves or boots.
- Welding equipment should not be left unattended with the current switched on.
- When welding work is finished, the electrode should be removed from the holder and the power supply should be switched off.
- When welding is carried out on a damp place, an insulated mat should be used, or rubber boots should be worn.
- Appropriate welding current ratings should be used for specific types of welding electrode. The supplier’s instructions should be followed in making the choice.
- Electric-arc welding generates very strong UV light. The welding operation must be properly enclosed by appropriate fences to protect people in the vicinity from being harmed by the strong UV light emission.
Welding and cutting operations in confined spaces should be avoided as far as practicable. If welding and cutting work in a confined space is unavoidable, the following safety precautions must be strictly followed:
- Without prejudice to the safety precautions mentioned below, the requirements stipulated in the Factories and Industrial Undertakings (Confined Spaces) Regulations must be followed.
- Appropriate pre-entry screening procedures for safe entry of confined spaces must be performed.
- Sufficient ventilation arrangement must be arranged.
- The surrounding work atmosphere must be constantly monitored with appropriate gas detection equipment.
- Cylinders should not be taken inside the confined space to avoid the risk of gas leakage through the cylinder connections or regulators.
- Welding equipment must be withdrawn during work breaks to prevent the possible build-up of gases leaking from the equipment.
Chapter 13 of this Manual describes the proper selection and use of appropriate personal protective equipment.
- Eye Protection
- The proper type of eye protectors must be worn by welders when carrying out welding operations.
- Eye protectors for welding operations should comply with BS 1542 and BS 679 or equivalent standards. Ordinary sun glasses do not provide adequate protection in welding operations.
- Persons working in the vicinity of arc welding are at risk of exposure to UV radiation. Screens should be placed around the welder's work area to protect persons nearby from UV exposure.
- Respiratory Protection
- Adequate local exhaust ventilation should be provided for welding and cutting operations to prevent welders and people nearby from inhaling excessive harmful gases or fumes.
- When there is a possibility of inhaling gases or fumes, appropriate respirators should be worn by the welder and other persons in the area who may be affected. However, respirators should not be used as a substitute for effective ventilation.
- Body/Skin Protection
- Clothing and gloves with sufficient electrical insulating capacity should be worn by the welder when carrying out electric arc welding and cutting operations in order to avoid electrocution.
- Gloves with sufficient thermal insulation capacity should be worn when handling hot objects.
- Light-coloured and long-sleeve clothing should be worn to guard against UV radiation from the electric arc welding process.
- Hearing Protection
Certain types of welding and cutting operations, such as plasma welding, will create loud noise which can cause hearing loss. Proper types of ear muffs or ear plugs should be worn by the welders.
7. PRESSURE SYSTEM
The sudden or uncontrolled release of pressure can cause severe injury and/or property damage.
This section describes the hazards and discusses appropriate safety precautions and requirements to avoid accidents associated with pressure systems.
There are many kinds of pressure containers, ranging from aerosol cans, boilers, air receivers, gas cylinders, hydraulic lines, etc. Once pressurized, pipes, hoses and equipment will also become “pressurised containers”.
The hazards involved in the use of pressure systems are primarily those relating to over-pressure, over-temperature, induced vacuum, inadequate safety device, or improper operation etc. These types of conditions can cause pressure containers to rupture with explosive force that can result in serious injury and/or property damage. The weakest points of pressure containers are usually at the joints, covers, seals or relief devices. Corrosion or physical defects in the system may also create a weak point in the container.
A leak in an unrestrained container may create sufficient force from the released gas to set the container in motion. For example, a broken valve fitting on a pressurized gas cylinder can propel the cylinder like a missile, the momentum of which can drive the cylinder through a wall. A sudden release of materials under pressure may produce a shock wave capable of knocking people or objects down or causing other damages. Furthermore, flying materials can also cause injuries and damage.
Leaking materials may have dangerous properties inherent to their physical, toxic or reactive characteristics. Contact with hot water or high pressure steam will cause thermal burns. Corrosive or toxic materials such as caustics or acids may cause chemical burns or poisoning.
Improper operation of pressure systems can also be hazardous. Incorrect activation or deactivation of pressure systems can induce vacuums or impart other pressure differentials that may result in explosions or implosions.
There are two major sets of ordinance controlling the safe use of pressure systems in Hong Kong:
The Boilers and Pressure Vessels Ordinance
This ordinance controls the safe use of boilers and pressure vessels. Under the ordinance,
A boiler refers to any closed vessel in which for any purpose steam is generated under pressure greater than atmospheric pressure and also means any economizer used to heat water being fed into any such vessel that is wholly or partly under pressure when steam is shut off, and any vessel in which oil is heated at a pressure greater than atmospheric pressure.
Pressure vessel means an air receiver, a steam receiver and a portable gas generator.
Before a boiler or a pressure vessel is put into use, it has to be certified by a government appointed examiner and registered under the requirements of the ordinance. The boiler or pressure vessel will have to be periodically examined and certified by a government appointed examiner when it is being put into use.
The certification and registration and the subsequent periodic examination of boilers and pressure vessels at HKUST may be coordinated through appropriate supporting units.
Documents on design and manufacturing of boilers and pressure vessels should be obtained from the manufacturers or suppliers for the necessary certification and registration process.
Dangerous Goods Ordinance
This ordinance controls the storage and use of compressed gas cylinders which are classified as Category 2 dangerous goods under the ordinance.
The safety measures and practices associated with storage, handling and use of compressed gas cylinders are described under separate headings below.
General Safety Measures
Operational safety procedures (OSP) with appropriate risk assessments and corresponding safety control measures should be established for the operation of pressure systems (refer to Chapter 2 Section 1 Work Planning for details).
- Employees who have to work with pressure systems should be properly trained on the potential hazards and appropriate safety precautions.
- Pressurized containers should not be exposed to direct sunlight or other sources of heat to avoid pressure from building up in the containers.
- The release of pressure from containers should be controlled to prevent injuries to nearby people.
- Equipment must be de-energized and depressurized before it can be worked on. Establish and implement appropriate tag out and lock out procedures when servicing pressurized equipment.
Pressurized Fluids and Gases
Gases and liquids pressurized under pressure can be dangerous if they are not handled properly. Examples of these systems include paint sprayers, hydraulic and pneumatic tools and equipment.
Negative pressure can also be dangerous where glass utensils may be crushed or undergo implosion when vacuum is being drawn.
Pressurized gases and fluids can cause injuries. Major hazards include:
- Eye Injuries
Exposing the eyes to pressurized gas can lead to serious injuries.
- Injection Injuries
Injection injuries occur when a fine stream of gas of fluid enters the body such as penetration into the skin. Fluid injected through even a tiny hole in the skin can migrate throughout several layers of tissue and is extremely difficult to remove. Injection injuries typically involve the fingers and hands, and sometimes the arms, face and other parts of the body. A gas injected under the skin may create embolisms in the blood stream that can interrupt lung or heart functions if they are allowed to migrate there.
- Whipping of Lines
Fluid moving through a nozzle can create reactive forces on the nozzle. If the forces are large enough, they can cause the nozzle and hose to move or whip which may cause serious injuries when it strikes somebody. Likewise, this whip-like motion can cause collateral damage which could create additional hazards such as chemical spills.
- Reduce the pressure of the system to a lower level if possible. Setting pressure regulators on general use air lines to 30 psi or less can minimise danger to users.
- People who work around compressed air lines, hydraulic systems and other pressurized fluid and gas equipment should have knowledge about the hazards. They should learn not to place fingers or hands against a stream and not to place the stream near anyone else. Protective gloves and clothing may help reduce injection injuries. The use of compressed air to blow away dusts or dirt on clothes or bodies is strictly forbidden.
- Workers should be clear of potential rupture points when pipelines and process equipment are undergoing pressure tests. During such tests the pressure should be increased incrementally with a brief holding period between each increase. Instruments for reading pressures should be so arranged that they are clearly visible at all times to workers who are located at a safe distance.
- Pressurized hose or lines that are unavoidably located near people should be protected with guards of sufficient strength to ensure that the hoses are adequately restrained if a leak or rupture occurs.
- Solid lines (e.g. metal pipes) do not whip or leak as readily as flexible hoses which can develop leaks from vibration, pressure cycles and aging. Therefore, where high pressure lines must come close to people, solid lines with tight, well-maintained fittings should be used.
- When flexible high pressure lines must be used, the connections should be well-maintained and frequently examined to prevent any accidental detachment of the line, resulting in uncontrollable whipping of the line. Hose clamps with restraining chain should be fixed to minimize the whipping effect of flexible hoses should they get loose accidentally.
- Pipe lines must never be connected or disconnected when there is any pressure in them.
Safety Measures and Practice for using Compressed Gas Cylinders
- Cylinders must be stored in cool, dry and well ventilated places. Cylinders in excess of the exempted quantity must be stored in approved dangerous goods stores.
- Cylinders must be kept away from sources of ignition or excessive heat.
- Cylinders must be stored upright and secured using racks, chains and straps in order to prevent them from falling.
- Cylinders must not be placed where objects may strike or fall on them, possibly damaging the cylinders or their components.
- Cylinders must not be placed along fire escape routes.
- Incompatible gases must not be stored close together. Oxygen cylinders must be stored away from flammable gases.
- Cylinders not in use should be returned to the store.
- Cylinders should be correctly tagged “full”, “in-use” or “empty”. Cylinders should be considered empty while positive pressure (25 psig or greater) still remains, in order to prevent suck-back and contamination (i.e. never completely empty a re-useable compressed gas cylinder).
- Cylinder valve of “empty” cylinders must be closed to avoid contaminants from getting into the cylinder.
- Cylinders should be transported with proper cylinder carts. Cylinders must be securely tied down onto the carts.
- Cylinders must be secured with chains or ropes to a cradle or platform before they are moved by crane, hoist, or forklift.
- Do not drag, roll, or slide cylinders. Cylinder valves should be protected with caps during transportation.
- Never drop a cylinder or permit cylinders to strike each other violently.
- Protect cylinders from any object that will produce a cut or abrasion in the surface of the metal.
- Never accept or use a leaking cylinder.
- Cylinders must be clearly marked with the content of the gases inside. Do not rely on the colour of the cylinders for identifying their content. Confirm cylinder contents by label before using.
- Some compressed gases are more hazardous than others. Make sure that you know the hazardous properties of the content of a cylinder and the appropriate precautions in handling the gas. You can get the information by studying the Safety Data Sheets (SDS) for the gas.
- Any cylinder with a valve that cannot be opened by hand or using a manufacturer supplied opening device must be returned to the supplier. Do not use a pipe wrench, hammer, or extension rod to open or loosen a cylinder valve. Such practices can result in serious injury and/ or property damage.
- Cylinder must not be used without an appropriate regulator. Compressed gas regulators for different types of gases cannot be used interchangeably. Use only the right type of regulator for the right gas.
- Do not force fit regulators or fittings to cylinders.
- Cylinders, cylinder valves, couplings, regulators, hoses, and apparatus must be kept free of oily or greasy substances. This is especially important for oxygen cylinders. Not observing this may result in an explosion. Store and handle regulators and fittings properly to prevent contamination of oil or grease.
- Fittings and piping which contain copper must not be used for acetylene gas in order to prevent the formation of explosive compounds.
- Gases should not be mixed inside cylinders. Experimental set-up requiring such practice should include an OSP with appropriate risk assessment addressing the hazards and stipulating the controls.
- Close cylinder valves when not in active use.
- Whenever an oxidizer and a fuel gas are used (such as in gas welding), “flash back arrestor” must be fitted for each gas.
- Gaseous acetylene under pressure may decompose with explosive force. Never use acetylene gas at pressures in excess of 15 psig.
- Inspect gas cylinders regularly for obvious signs of defects, deep rusting, or leakage.
- Hoses and fittings used for connection to compressed gas cylinders must be of adequate pressure ratings.
- Hoses should be securely connected to cylinders by appropriate fixing device. Flexible hoses should be connected with proper hose clamps. Hose clamp with large contact surface should be used for clamping flexible hose on glass hose tail to prevent damaging the glass fitting.
- Never strike an electric arc or direct a flame at a cylinder, or include a cylinder as part of an electric circuit.
Proper Procedure for Opening and Shutting Down Cylinder Valves
- Check if the proper type of regulator is fixed to the cylinder valve outlet. Check if the pipe lines and hoses are properly connected and securely clamped. Correct any discrepancies before proceeding.
- Turn the pressure adjusting screw of the regulator counter-clockwise until it turns freely to ensure that the regulator is OFF.
- SLOWLY open the cylinder valve until the cylinder pressure gauge on the regulator reads the cylinder pressure. DO NOT stand in front of the regulator since it is the weakest point of the system and there is a high risk of the regulator being blown off when thing goes wrong. Stand aside when opening the cylinder valve.
- With the cylinder valve open, set the desired delivery pressure by turning the pressure adjusting screw clockwise until the desired pressure is reached.
- Always keep the cylinder valve free of obstructions such as tools, rags, and hoses, etc. to permit easy and immediate gas cutoff.
- When the work is finished, always turn off the cylinder valve first and then the regulator. The pressure gauges should be brought back to zero. Use the cylinder valve instead of the regulator valve for turning off the gas.
- Before removing the regulator, make sure that the cylinder valve is closed and the pressure gauges read zero.
Implosion under Negative Pressure
Implosion under negative pressure is another form of hazard associated with pressure. Implosions in laboratory facilities may occur when vacuum pumps, or other equipment that creates negative pressure, is used in conjunction with glass containers, or when such equipment is used in the vicinity of glass windows and viewpoints. When an implosion occurs, glass fragments may be propelled in all directions. In addition to cuts, these fragments may inject toxic, corrosive or irritant products into the body. Containers containing hazardous materials may splash onto people or cause spills during an implosion incident.
- Maintain equipment in good working order, with all safety systems installed.
- Use plastic containers instead of glass containers wherever possible.
- If glass containers have to be used, protect the glass containers with plastic coating. The size of glass containers should be minimized. Adequate shielding should be set up between the glass container and people.
- Wear safety goggles and other appropriate protective equipment, such as face shields and protective clothing, when implosion hazard exists.
- Conduct experiments that have the potential for implosion inside a fume hood with the vertical sash lowered.
8. CONFINED SPACES
Confined space accidents are often among the most tragic cases of occupational deaths. Invisible and deadly, the hazardous atmosphere inside a confined space can often take more than one life as heroic efforts are made to rescue the initial victim.
The purpose of this section is to explain the potential hazards that could exist in confined spaces and set out appropriate safety procedures to ensure that, whenever it is necessary for someone to enter a confined space, all necessary precautions are taken against dangers resulting from the presence of noxious fumes, toxic gases, oxygen deficiency, excessive heat, humidity and other hazards that can exist in a confined space.
The relevant requirements stipulated in the Factories and Industrial Undertakings (Confined Spaces) Regulation should also be observed.
B. Determination of Confined Spaces
The term confined space embraces a wide range of areas, but it normally refers to those areas in which, by virtue of their enclosed nature, arise a reasonably foreseeable risk, including:
- loss of consciousness of any person inside arising from exposure to gas, fume, vapour or the lack of oxygen;
- serious injury to any person inside arising from a fire or explosion;
- loss of consciousness of any person inside arising from an increase in body temperature;
- drowning of any person inside arising from an increase in the level of liquid or other free flowing materials (e.g. mud);
- entrapment of person(s) inside.
Without limiting the generality of the above definitions, the following areas can be regarded as typical confined spaces:
- A completely enclosed structure with limited access through a manhole (e.g. storage tank, boiler, pressure receiver and vessel).
- A structure or vessel of such a depth as to require special means of entry, with its top usually open e.g. chamber, tank, vat, pit, well, caisson, vault, bin, silo and shaft.
- A structure or ducting of sufficient length with inadequate cross-ventilation e.g. tunnel, pipeline, flue, duct and sewer.
- A room or enclosed area in which dangerous fumes such as toxic, flammable, explosive or corrosive fumes are present.
If there is any doubt in determining whether a particular location should be classified as a confined space, HSEO should be consulted for making the appropriate assessment.
A confined space may become hazardous when one or more of the following conditions arises:
Toxic gases or fumes can build up from the toxic substances exist inside the confined space or by the work being carried out inside the confined space, e.g. use of chemicals, welding operations, operation of internal combustion engines, etc.
The causes for the accumulation of flammable or explosive gases or fumes are similar to those for toxic gases or fumes as described above.
Excessive oxygen concentration in the atmosphere can also be hazardous as it promotes combustion.
- Accumulation of toxic gases or fumes
- Accumulation of flammable or explosive gases or fumes
- Oxygen Deficiency
The normal oxygen content in the atmosphere is 20.9 %. Oxygen content below 18 % can endanger human lives. A number of situations can lead to oxygen deficiency inside a confined space. The following are some of the typical situations:
- oxygen is used up without adequate supply in a totally enclosed area (hot work operations will accelerate the consumption of oxygen);
- oxidation of metal parts inside the confined space (totally enclosed ferrous tanks are especially vulnerable);
- oxygen is displaced by heavier gases (may not be toxic) such as carbon dioxide, nitrogen, etc.;
- oxygen inside a tank or vessel is driven out in a purging process.
- Health hazards
- Biological hazards, such as mold, mildew and spores, frequently found in dark, damp spaces can irritate the respiratory system.
- Bacteria and viruses found in sewage can also threaten the body with a variety of diseases.
- High temperature
Such hazard exists in confined spaces where the temperature inside is too high, such as a large-scale boiler or furnace. This may result in loss of conscious of the person(s) inside, or heat-related illnesses, such as heat cramp.
- Ingress of hazardous substances
Such hazard exists in confined spaces into which substances such as chemical substances, steam or water may be discharged. Typical examples include chemical storage tanks, water tanks, etc.
Engulfment hazard exists in areas where loose materials such as flour, sawdust, sand or mud, etc. are contained. When disturbed, the loose materials may collapse and bury the person(s) inside.
It requires the full commitment and co-operation of all parties concerned to ensure the health and safety of persons working in a confined space.
The management should ensure that every operation in the confined space is safe and without risk to the personnel working inside, or in the vicinity of the confined space. Specific duties include the following:
- To identify all operations to be conducted in confined spaces and the locations of those spaces.
- To ensure that the supervisors and workers involved in any operations in a confined space are:
- adequately trained and qualified for the work.
- fully aware of the potential hazards.
- fully understand and will comply with the safety procedures set out in this section.
- To give sufficient prior notice to HSEO for making any necessary pre-entry safety arrangements, such as the conduct of risk assessment for the confined space.
- To take all necessary safety precautions as recommended in the relevant Risk Assessment Report prepared by a Competent Person appointed to conduct the risk assessment for the confined space.
- To issue an appropriate "Confined Spaces Entry Certificate" as required by the Factories & Industrial Undertakings (Confined Spaces) Regulation.
- Employees who are assigned to work in confined spaces
Employees should co-operate with the management and HSEO in respect of the required safety arrangements, and take reasonable care for the health and safety of themselves and other persons who may be affected by his/her acts or omissions at work. As far as working in confined spaces is concerned, employees should:
- Attend appropriate safety training courses as required by the management.
- Follow all relevant procedures, instructions and advice established and given by the management and HSEO for safe working in confined spaces.
- Make full and proper use of all necessary safety equipment and emergency facilities provided by the management, and report to the management any faults and defects identified.
- The Health, Safety and Environment Office (HSEO)
HSEO is responsible for providing all necessary advice and assistance to the respective units for safe entry into confined spaces, which may include:
- Testing and monitoring of the air condition in the confined space upon request by the concerned unit;
- To conduct appropriate risk assessments of the confined space upon request by the concerned unit;
- To provide or arrange for appropriate safety training for staff who need to be involved in confined spaces operations.
E. Training and Qualifications
Employees involved in confined spaces operations have to be trained and obtain the following qualifications as appropriate:
Employees who need to enter or work in a confined space have to attend an approved safety training course (note 1) and obtain a valid "Certified Worker" certificate.
Employees to be appointed to conduct risk assessments for confined spaces have to attend an approved safety training course (note 2) and obtain a valid "Competent Person" certificate.
Note 1: This is a one-day training course approved by the Labour Department. HSEO has obtained the approval to conduct this training course.
Note 2: This is a two-day training course approved by the Labour Department. HSEO has obtained the approval to conduct this training course.
F. Documentations for Confined Space Operations
Confined Space Entry Request Form
This form is to be submitted to HSEO by the concerned unit indicating the date(s), location and nature of the confined space operation. Specific assistance needed from HSEO, such as performance of risk assessment, should be indicated in the Request Form. A pro forma of the request form is attached as Appendix 5D1.
Confined Space Risk Assessment Report
This report is to be prepared by a Competent Person appointed to conduct a risk assessment for operations in a confined space. A pro forma is attached as Appendix 5D2.
Confined Space Entry Certificate
This certificate is to be issued by the management of the concerned unit for the operations in a confined space to certify that the confined space is safe for entry after all necessary safety precautions in relation to the hazards identified in the Risk Assessment Report have been taken. A pro forma of the certificate is attached as Appendix 5D3.
G. General Procedures for Safe Operations in Confined Spaces
- When work is to be carried out in a confined space, the unit planning for the work should complete and submit a "Confined Space Work Request Form" to HSEO, giving sufficient time in advance for HSEO to make the necessary pre-entry safety arrangements, such as risk assessment, air monitoring, etc.
- The unit should arrange for a risk assessment to be conducted by a Competent Person on the working conditions in the confined space with recommendations on measures to be taken in relation to safety and health of workers while working in that space. The risk assessment can be conducted by a Competent Person in the unit, or assistance can be sought from HSEO for the assessment. An appropriate "Risk Assessment Report" should be prepared by the Competent Person and submitted to the management of the unit.
- Upon receiving the "Risk Assessment Report" from the Competent Person, arrangements should be made by the unit to comply with all recommendations made in the report.
- A "Confined Space Safe Entry Certificate" should then be issued by the unit stating that all necessary safety precautions in relation to the hazards identified in the Risk Assessment Report have been taken. The period during which workers may remain safely in the confined space should be stated in the certificate.
- Only "Certified Workers" are allowed to enter or work inside a confined space.
- The Risk Assessment Report and the Safety Entry Certificate should be posted at the entrance of the confined space for easy reference.
- When the work is being undertaken in a confined space, a person has to be posted outside the confined space to maintain communication with the workers inside. The person posted at the outside has to be a "Certified Worker" and familiar with the emergency procedure for confined space operations.
- The Safe Entry Certificate should be properly cancelled with HSEO when the works in the confined space have been completed and all persons have got out of the confined space.
H. Specific Procedures for Special Work Conditions
Depending on the nature of risk and the existence of appropriate hazard control installations, specific entry procedures have been established for certain work sites. The respective procedures should be followed when working in those areas. The established "specific procedures" are listed in Appendix 5D4 and attached to as follows:
- Entry Procedures for Underground Pump Rooms
- Entry Procedures for Main Building Service Tunnel
- Entry Procedures for Sewage Tunnel
- Entry Procedures for Sea Water Pump House/UG2 Service Tunnel
- Entry Procedures for Routine Cleaning/Maintenance/Repair
- Security Control Centre (SCC) must be informed before any confined space entry.
- When work is being carried out inside a confined space, a person (the attendant) must be posted at the entrance of that confined space. The attendant must be a “Certified Worker” or “Competent Person”.
- The attendant stationed outside must communicate closely with the persons staying inside the confined space and to watch out for any abnormal conditions.
- Persons inside the confined space should stay alert and watch out for any abnormal changes in the environment and in their health conditions, such as smell of gas, feeling of dizziness, etc. They must evacuate the confined space immediately and report the situation to their supervisor or seek help from the SCC. They must also warn all other persons inside the confined spaces about the situation and ask them to leave.
- In the event that someone is overcome inside the confined space, the attendant stationed outside must immediately call SCC for assistance. He/she must not enter the confined space to exercise rescue without wearing a proper breathing apparatus set and without ensuring that there is no other imminent dangers in the confined space.
- When informed of an emergency, the Security Duty Controller should make sure that he has obtained the necessary information regarding the emergency. He should then immediately call the Fire Services Department for assistance if necessary. At the same time, he should dispatch a team of adequate number of Security personnel to the scene to provide assistance. The Security personnel dispatched should have adequate knowledge about the hazards in confined spaces. They should also bring with them the necessary rescue equipment, including safety harnesses and lifelines, resuscitators and SCBA, etc.
- Before entering a confined space for the rescue attempt, appropriate gas detection equipment must be used to verify the atmospheric conditions so that appropriate safety measures can be determined for the rescue and for the safety of the rescuer.
- HSEO should also be informed of any emergencies concerning with confined spaces entries.