Many of the air-conditioning (AC) systems of highrise apartments are mounted externally on the side of the building. An example is shown in the photos below.
The installation and maintenance of these external AC units pose various hazards. Access to the AC units is mostly through the windows which, if not managed carefully, can lead to fatal falls for the workers involved in the works. In addition, while work is being carried out, there is a risk of the AC unit, tools or brackets falling off and hitting passers-by below.
To ensure safe installation and maintenance of external AC units, please follow the safety recommendations listed below (list is not exhaustive):
1. Conduct risk assessment: Before the start of work, it is important to conduct an adequate risk assessment to identify all potential hazards and the risks involved. Control measures and safe work procedures must be established and implemented. In this situation of high-rise AC system installation or maintenance, the following should be considered and addressed before starting work:
a. Take steps to prevent the worker from falling from height;
b. Reduce the risk of falling objects;
c. Provide adequate supervision and appropriate personal protective equipment (PPE); and
d. Demarcate the hazardous area and place appropriate warning signs for the public.
2. Ensure proper supervision: It is important to appoint a competent person to supervise the workers. This person should ensure that :
a. Only trained and competent workers are allowed to work in such an elevated location;
b. Safe work procedures are being followed;
c. All reasonable precautions have been taken to mitigate the risk of the worker falling or being hit by falling objects (e.g. ensuring that workers don the appropriate PPE); and
d. Workers are not exposed to other hazards such as electrical hazards, ergonomic hazards, etc.
3. Provide personal protective equipment: Workers should be provided with a work restraint system. This would include the use of safety harnesses or restraint belts. When using safety harnesses or restraint belts, they must be securely anchored to a suitable anchor point or static line. Workers should also be equipped with an appropriate tool carrier harness. This is to secure the tools and prevents any tools from dropping accidentally while the work is being conducted.
4. Cordon off working area: It is necessary to cordon off the area underneath the working area so that it prevents inadvertent public access while work is being done above. Prominent signage is to be provided to alert the public.
Wednesday, September 29, 2010
Lifting Supervisor Jailed Four Weeks for Fatal Accident
From Singapore:
On 14 January 2010, a site supervisor was jailed 4 weeks for performing a reckless act that resulted in the death of one worker in a lifting accident on 12 October 2007.
The site supervisor was directly in charge of 20 workers who were involved in demolition and structural works. At the time of the accident, he instructed 2 other workers, including the deceased, to help in the lifting of a timber formwork using a mobile crane. During the lifting, the wire rope used in the lifting gave way. The formwork fell about 9 metres and hit one of the workers.
Investigations found that the trained lifting supervisor failed to ensure that the two workers involved were trained riggers and were properly briefed to perform the lifting activity. He also endangered the workers’ safety by exposing them to falling object hazard during the lifting activity.
The Commissioner for Workplace Safety and Health, Ho Siong Hin, said that the 4-week jail term passed by the Court underscores the gravity of the offence and the importance for supervisors to uphold workplace safety. The accident could have been prevented had the supervisor ensured that the necessary safety precautions were in place.
On 14 January 2010, a site supervisor was jailed 4 weeks for performing a reckless act that resulted in the death of one worker in a lifting accident on 12 October 2007.
The site supervisor was directly in charge of 20 workers who were involved in demolition and structural works. At the time of the accident, he instructed 2 other workers, including the deceased, to help in the lifting of a timber formwork using a mobile crane. During the lifting, the wire rope used in the lifting gave way. The formwork fell about 9 metres and hit one of the workers.
Investigations found that the trained lifting supervisor failed to ensure that the two workers involved were trained riggers and were properly briefed to perform the lifting activity. He also endangered the workers’ safety by exposing them to falling object hazard during the lifting activity.
The Commissioner for Workplace Safety and Health, Ho Siong Hin, said that the 4-week jail term passed by the Court underscores the gravity of the offence and the importance for supervisors to uphold workplace safety. The accident could have been prevented had the supervisor ensured that the necessary safety precautions were in place.
Safe Handling of Compressed Gas Cylinders
Compressed gas cylinders are commonly used in the different industries for a variety of operations. These cylinders are heavy, normally weighing about 80 kilograms each. They are specifically designed to contain gases, such as Oxygen, Nitrogen, Argon, Helium, Carbon Dioxide and Hydrogen. These gases are compressed and stored under high pressure. The gas is released through a valve which regulates its discharge.
Compressed gas cylinders are dangerous because:
• They may contain gas that may be toxic, asphyxiating or flammable. The gas is also stored under high pressure.
• They are usually heavy and can cause injury, such as sprains and strains, if not well handled.
• If the cylinders are tipped, dropped, heated or knocked, they may rupture and explode, sending sharp metal pieces, like shrapnel, blasting through the area.
• The release of pressure from a gas leakage could generate a huge amount of force. It may also propel the cylinder, leading to injuries;
Compressed gas cylinders are dangerous because:
• They may contain gas that may be toxic, asphyxiating or flammable. The gas is also stored under high pressure.
• They are usually heavy and can cause injury, such as sprains and strains, if not well handled.
• If the cylinders are tipped, dropped, heated or knocked, they may rupture and explode, sending sharp metal pieces, like shrapnel, blasting through the area.
• The release of pressure from a gas leakage could generate a huge amount of force. It may also propel the cylinder, leading to injuries;
Ensuring Safe Diving Operations
Commercial diving operations are inherently hazardous. Various hazards, such as tide and current changes, poor visibility and compression and decompression pressure injuries can jeopardise divers’ safety and lead to severe or even fatal injuries.
Accordingly, the risk of diving work activities needs to be effectively managed. Work activities underwater should be conducted in a controlled and safe manner. The diving contractor needs a clear understanding of the task and associated risks. Divers need to be adequately trained and competent to carry out work underwater. The type of equipment used should also be capable of carrying out the task safely, and backup systems should be available to cater for emergencies.
Accordingly, the risk of diving work activities needs to be effectively managed. Work activities underwater should be conducted in a controlled and safe manner. The diving contractor needs a clear understanding of the task and associated risks. Divers need to be adequately trained and competent to carry out work underwater. The type of equipment used should also be capable of carrying out the task safely, and backup systems should be available to cater for emergencies.
Unsafe Roof Work Resulted in Fatality
In recent years, a significant number of workers have been killed while working on roofs. Some of these accidents involved workers stepping on and falling through fragile roofs.
Worker Falling from Height during Lifting Process
A construction worker died after falling off a building under construction while erecting a formwork.
On the incident night, at around 9.40pm, the worker was stationed at the fourth level of a building under construction. An inner formwork was lifted to the same floor by a crawler crane and bolted to the floor slab. The worker then climbed onto the platform of the formwork to remove the 2 attachments for lifting the formwork. After removing them, the worker re-attached the lifting attachments onto the crane slings and the signalman gave the go-ahead for the crane to hoist the slings away.
However, one of the lifting attachments caught the rebar cage beside the formwork. The rebar cage was pulled out of its position by the crane and toppled 20m to the ground below. The worker who had earlier anchored his safety harness to the rebar cage fell together with it.
Recommendations*
For crane operators:
1. Prevent Entanglement of Load Line: Crane operators need to be alert throughout the entire lifting process. Before moving the crane’s load line, the crane operator must ensure that there is no entanglement of load line or slings with objects nearby. If the operator does not have a clear view of the lifting operations, he should adhere closely to the instructions of the signalman. In this incident, the slings (with the attachments) should have been raised sufficiently above the height of the rebar cage before slewing them over the cage.
2. Stop Slewing if movement is not smooth: The crane operator should avoid sudden movements of the load line at high speed. Start any lifting process slowly so that any abnormalities can be detected. If the operator feels abnormal resistance to the crane’s movement, he should halt the process and check (with the aid of the signalman) for possible entanglement.
For lifting crew:
3. Lifting Signalman: Lifting signalman must stay alert throughout the lifting operation, particularly during slewing of the load line. He must halt the lifting process immediately in the event of a load line entanglement.
4. Effective Communication: A system must be in place to ensure effective communication between lifting personnel, particularly between the operator and signalman. This could be done through:
• Hand signals if the signalman is in clear sight of the crane operator
• Suitable communication equipment such as walkie talkies. It is important that the operator and signalman can speak and understand a common language.
General recommendations:
5. Conduct Risk Assessment: Prior to the start of work, conduct an adequate risk assessment to identify all potential hazards and the risks involved. Appropriate control measures and safe work procedures must be established and implemented. For this case, some of the potential hazards include:
• Possible entanglement of load line with surrounding structures
• Poor visibility due to inadequate lighting
• Ineffective communications between signalman and crane operator
6. Safe Lifting Procedure: Companies should put in place procedures to mitigate the risk of load line getting entangled with the surrounding structures. These could include ensuring that:
• Lifting signalman have clear sight of the lifting process at all time
• Lifting signalman give clear instructions to crane operator
• There is sufficient lighting to ensure good visibility of the lifting process, especially if the work is carried out at night
7. Safe working at height: Companies involved in works carried out at height must implement appropriate fall protection measures for workers. When fall arrest systems are utilised, proper anchorage points or anchorage systems must be made available. In addition, if works are to be carried out at night, sufficient lighting must be provided.
On the incident night, at around 9.40pm, the worker was stationed at the fourth level of a building under construction. An inner formwork was lifted to the same floor by a crawler crane and bolted to the floor slab. The worker then climbed onto the platform of the formwork to remove the 2 attachments for lifting the formwork. After removing them, the worker re-attached the lifting attachments onto the crane slings and the signalman gave the go-ahead for the crane to hoist the slings away.
However, one of the lifting attachments caught the rebar cage beside the formwork. The rebar cage was pulled out of its position by the crane and toppled 20m to the ground below. The worker who had earlier anchored his safety harness to the rebar cage fell together with it.
Recommendations*
For crane operators:
1. Prevent Entanglement of Load Line: Crane operators need to be alert throughout the entire lifting process. Before moving the crane’s load line, the crane operator must ensure that there is no entanglement of load line or slings with objects nearby. If the operator does not have a clear view of the lifting operations, he should adhere closely to the instructions of the signalman. In this incident, the slings (with the attachments) should have been raised sufficiently above the height of the rebar cage before slewing them over the cage.
2. Stop Slewing if movement is not smooth: The crane operator should avoid sudden movements of the load line at high speed. Start any lifting process slowly so that any abnormalities can be detected. If the operator feels abnormal resistance to the crane’s movement, he should halt the process and check (with the aid of the signalman) for possible entanglement.
For lifting crew:
3. Lifting Signalman: Lifting signalman must stay alert throughout the lifting operation, particularly during slewing of the load line. He must halt the lifting process immediately in the event of a load line entanglement.
4. Effective Communication: A system must be in place to ensure effective communication between lifting personnel, particularly between the operator and signalman. This could be done through:
• Hand signals if the signalman is in clear sight of the crane operator
• Suitable communication equipment such as walkie talkies. It is important that the operator and signalman can speak and understand a common language.
General recommendations:
5. Conduct Risk Assessment: Prior to the start of work, conduct an adequate risk assessment to identify all potential hazards and the risks involved. Appropriate control measures and safe work procedures must be established and implemented. For this case, some of the potential hazards include:
• Possible entanglement of load line with surrounding structures
• Poor visibility due to inadequate lighting
• Ineffective communications between signalman and crane operator
6. Safe Lifting Procedure: Companies should put in place procedures to mitigate the risk of load line getting entangled with the surrounding structures. These could include ensuring that:
• Lifting signalman have clear sight of the lifting process at all time
• Lifting signalman give clear instructions to crane operator
• There is sufficient lighting to ensure good visibility of the lifting process, especially if the work is carried out at night
7. Safe working at height: Companies involved in works carried out at height must implement appropriate fall protection measures for workers. When fall arrest systems are utilised, proper anchorage points or anchorage systems must be made available. In addition, if works are to be carried out at night, sufficient lighting must be provided.
Shutting of Door on Worker at the Drill Floor
In this incident, workers were deployed to carry out grinding work on the drill floor of an offshore drilling rig. One of them was assigned to grind the “I” beams of a collapsible door on the drill floor. The door consisted of 2 heavy steel panels which could be swung open upwards, and secured in the open position with a security pin. The worker was later found with his head trapped between the 2 door panels. He was sent to hospital where he subsequently succumbed to his head injury.
Summary of Findings:
Investigations revealed that the worker did not secure the heavy steel door in the proper manner. Instead of the security pin, a piece of wire was found attached to the door panel. The wire was not strong enough to hold the heavy door panel, and led to the door panel shutting down on the worker.
Summary of Findings:
Investigations revealed that the worker did not secure the heavy steel door in the proper manner. Instead of the security pin, a piece of wire was found attached to the door panel. The wire was not strong enough to hold the heavy door panel, and led to the door panel shutting down on the worker.
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