As Second Engineer, list all the potential hazards with regard to hot work on a fuel oil heater located inside a bunker fuel oil tank. Explain how you carry out risk assessment for the hot work. What control measures do you employ so that residual risk shall be reduced as low as reasonably practicable (ALARP).

Potential hazards:

1. Fire/explosion: the fuel oil tank contains flammable fuel oil and flammable vapours; hot work (welding, grinding, cutting) can ignite the vapours or the oil, causing a fire or explosion.
2. Toxic/flammable vapours: the tank may contain toxic or flammable vapours (from the fuel oil) which are hazardous to personnel.
3. Oxygen deficiency: the tank may have an oxygen-deficient atmosphere (from the fuel oil vapours displacing the oxygen), which is a hazard to personnel entering.
4. Confined space: the tank is a confined space; entry is hazardous (oxygen deficiency, toxic gases, fire).
5. Burns: hot work and the hot surfaces can cause burns to personnel.
6. Electric shock: welding/electrical equipment in a hazardous area can cause electric shock.
7. Slips/trips/falls: working in the tank and on the heater can cause slips, trips, and falls.
8. Residual fuel/oil: residual fuel oil in the heater and the tank can ignite or cause burns.

Risk assessment for the hot work:

1. Identify the hazards (as above) and the persons at risk.
2. Evaluate the risks (likelihood and consequence) for each hazard.
3. Determine the control measures to reduce the risks.
4. Record the assessment and obtain the necessary permits (hot work permit, confined space entry permit).
5. Review the assessment with the personnel involved.

Control measures to reduce the residual risk to ALARP:

1. Isolate and drain the tank and the heater: empty the fuel oil from the tank and the heater, isolate the tank from the fuel system (close and blank the valves), and drain the residual oil.
2. Gas-free the tank: ventilate the tank and test the atmosphere (oxygen, flammable vapours, toxic gases) to confirm it is safe for hot work (e.g. oxygen 21%, flammable vapours below the lower explosive limit).
3. Clean the tank and the heater: remove the residual oil and sludge (wash and clean) so there is no flammable material.
4. Use a hot work permit and a confined space entry permit: the work is authorised and supervised, with a responsible person.
5. Provide fire-fighting equipment: have fire extinguishers and a fire watch in place.
6. Use proper PPE: flame-resistant clothing, gloves, goggles, and a breathing apparatus if required.
7. Ensure good ventilation: maintain ventilation during the work to remove any vapours.
8. Use safe equipment: use intrinsically safe/approved electrical equipment and proper welding equipment.
9. Post a fire watch: a person is stationed to watch for any fire and to extinguish it.
10. Monitor the atmosphere continuously during the work.
11. Train the personnel in the hot work and confined space procedures.
12. Have an emergency plan and rescue arrangements in place.

These measures reduce the residual risk to as low as reasonably practicable (ALARP).