CLEANING AND INSPECTION OF AN OILY BILGE TANK

1. Preparation: Identify the oily bilge tank, inform the watch/ duty engineer, and prepare a permit-to-work/ risk assessment. Check the tank contents and the MARPOL requirements.
2. Transfer the water/ oily water: The oily water in the tank is transferred to the appropriate oily water/ slop tank or to the oil-water separator (OWS) system for treatment, in accordance with MARPOL. The water is passed through the OWS and the clean water (below 15 ppm oil) is discharged overboard through the approved monitoring/ control system (only where permitted, e.g. outside special areas and at the required distance from land). The oil/ sludge is retained in the slop/ sludge tank.
3. Empty the tank: Pump out the remaining oily water/ sludge to the slop/ sludge tank or to a reception facility. Do not discharge any oil overboard (MARPOL reg 12/ 15). The tank is emptied as far as possible.
4. Clean the tank: Wash the tank (with hot water/ appropriate cleaning) and remove the sludge/ residue, transferring the washings to the slop tank. The tank is then gas-freed and made safe for entry.

Before entering:

• Isolate the tank (close/ secure the valves and connections).
• Gas-free the tank (ventilate) and test the atmosphere (O2, flammability, toxic gases) before entry.
• Complete an enclosed-space entry permit and arrange a stand-by watch, communication, and rescue arrangements.
• Use correct PPE and a lifeline/ harness.

While cleaning in progress:

• Maintain continuous ventilation and atmosphere monitoring.
• Keep the stand-by watch and communication.
• Use approved, low-voltage lighting and tools (no sparks/ ignition sources).
• Handle the cleaning chemicals/ water safely.
• Do not enter unless the atmosphere is safe; obey time limits.
• Keep the area clean and free of oil/ water to prevent slips.

Before cleaning:

• Check the tank contents and the MARPOL requirements.
• Check the transfer/ pumping arrangements and the OWS/ slop tank capacity.
• Check the tank is isolated and the atmosphere is safe (before entry).
• Check the cleaning equipment and PPE.

After cleaning:

• Inspect the tank internals (stiffeners, tank top/ bottom, bulkheads, suction, condition of coatings) for corrosion, pitting, cracks and damage.
• Check the tank is clean and free of oil/ sludge.
• Check the tank is gas-free/ safe for the next operation.
• Re-commission the tank (close the manhole, reconnect, and return to service).
• Record the cleaning and inspection.