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vapours (from asphalt, pitch, solvents) and oxygen.
Many solvents evaporate quickly at roof temperatures. Explosive mixtures of vapours can be readily formed
within confined spaces like high parapet walls, in atriums or in any space where little or no ventilation exists. And any
king of spark or flame can ignite the vapours.
Electrocution
Low voltage electricity can cause shock, muscle contractions, breathing difficulty, irregular heartbeat, severe burns and
death. The route that the current takes through the body affects the degree of injury. Current flowing from one finger to
another would not pass vital organ, while from one hand to another would pass through the heart and lungs.
Electrical tools should be properly grounded. The electrical cord should end in a three-prong grounding contact, or the
wires should be enclosed in a metal case with a special grounding attachment.
Employers are required to provide ground fault circuit interrupters for all outlets on construction sites that are not part of
the permanent wiring of the building. This is actually a fast-acting circuit breaker, which can shut off electricity in a
fraction of a second.
Aluminum or other metal ladders pose a serious electrical hazard around electrical equipment and energized lines.
Falling Objects
Tools, bricks, materials, buckets, boxes, pallets or almost anything dropped from a sufficient height can cause severe
damage. Head injuries, one of the highest compensated injuries to workers, often include brain damage.
Workers need protective head gear when working beneath people, tools and equipment.
Flying Objects
Objects can be projected my machines, from welding or grinding operations and can be windblown. Tear-off operations,
where power cutters, power brooms and power spudders are generally used, are the major source of flying substances.
The part of the body most often injured is the eyes.
Unguarded Machinery
Exposed blades and chains on powered machinery like hoists and roof cutters can severely lacerate and crush parts of the
body. Guards should always be fitted over moving parts to protect workers.
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For kettles and tankers, fir/explosion conditions arise when;
Oversized burners are used to fire the kettle, causing localized overheating of the heating tubes
creating a hot spot.
The temperature of the bitumen is brought up to the desired operation temperature too quickly.
Allowing the level of bitumen to drop to the level of the firing tubes, allowing excessively high
surface temperatures.
Heating the bitumen to its flash point (for asphalt, about 525-540; for pitch, about 450-475)
The temperature of the bitumen is hot enough to reach the auto-ignition level
In tankers, the vent pipe is clogged or plugged so that flammable vapours can build up to
explosive levels
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