Fuel Tank Repair Beside an Open Petrol Basin
Work is a two-bay workshop in Gampaha on a wet Tuesday. A 2016 150 cc commuter has a leaking fuel-tank seam. The apprentice has drained about 3 litres of petrol into an open plastic basin and set it on the bench beside a grinder. He wants to braze the seam in the same bay while you finish a brake job on the next bike. The bay has one wall fan, a 2 kg CO2 extinguisher at the door, and no fume extraction. The roller door is closed because of rain, and the temperature is 32 °C. He is wearing sandals, a cotton T-shirt and no eye protection. The supervisor wants the tank repaired before lunch so the customer can leave. The bike's petcock is still connected to the tank, and the fuel cap is off. Two other staff are working within 3 m.
1. List the immediate hazards and state what you would stop or change before any hot work begins.
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Immediate stop-work. The open basin of petrol is the primary hazard: at 32 °C it releases vapour continuously, and the vapour is heavier than air, so it collects at floor and bench level. The grinder and the brazing torch are ignition sources; the wall fan is not rated for flammable atmospheres and can spark. The closed roller door prevents dispersion. The petcock and open cap mean more fuel can escape. The apprentice in sandals and no eye protection is not prepared for fuel handling or hot work. I would stop the grinder and any hot work, switch off the fan and nearby equipment, move the basin to a well-ventilated outdoor area with a lid and bonding/grounding, wipe up spills with inert absorbent, and clear non-essential people from the bay. I would not continue the brake job in the same bay until the fuel is removed. Notify the supervisor that the planned sequence is unsafe.
2. Describe how you would prepare the tank and the bay for a safe repair, including PPE and fire precautions, and explain why each step matters.
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Prepare the tank away from the bike. Drain the fuel into an approved, bonded metal safety container with a lid, not an open basin, and store it outside the workshop. Remove the tank, cap the petcock, and purge the tank: fill with water, drain, then ventilate; or use an inert-gas purge. Never use a flame to 'burn out' vapour. Move hot work to a designated area outside or to a bay with explosion-proof ventilation and no combustibles within 10 m. Screen the work, keep a dry-powder or foam extinguisher within reach, and post a fire watch during and for at least 30 minutes after. PPE: nitrile gloves, goggles or face shield, flame-retardant coveralls, safety boots; no sandals. The apprentice may assist outside the hot-work zone only after instruction. If a proper purge, ventilation and fire watch cannot be provided, the hot work does not proceed; fit a replacement tank instead.
3. The supervisor says the CO2 extinguisher at the door is enough. Explain whether you agree and what you would do if the correct controls cannot be met.
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I would not accept one CO2 extinguisher at the door as sufficient. CO2 is useful for electrical fires and leaves no residue, but on a petrol fire it has limited cooling and the vapour can re-ignite from hot metal; the extinguisher is also behind the likely fire location. A dry-powder or foam extinguisher, a fire blanket, and a trained second person are needed. If the workshop cannot meet the controls-purged tank, outdoor or explosion-proof ventilation, ignition-source control, fire watch, PPE-I would refuse the hot work and explain why. The safe alternatives are to replace the tank with a sound used unit or to send the repair to a specialist tank shop. I would record the refusal and the reason, and ask the supervisor to put the decision in writing. The customer's deadline does not override the fire risk.