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Sludge discharge from ships - planning, preparation, safety checks & discharging ashore

Ship generated sludge are the residue from any oil separation process which is usually a mixture of water, solid material and high viscosity oil. Sludge oil thus results from the fuel or lubricating oil separators, waste lubricating oil from the main or auxiliary machinery, or waste oil from bilge water separators, oil filtering equipment or drip trays, (MARPOL).

In essence, sludge is a contaminant that results from the handling, mixing, blending, and pumping of heavy fuel while stored at, and after it leaves, the refinery. Storage tanks, heavy fuel pipelines, and barging can all contribute to the build-up of sludge. Water contamination of a high asphaltene fuel oil can produce an emulsion during fuel handling which can contain more than 50% water. Shipboard transfer pumps can frequently provide the necessary energy to produce emulsified sludges during normal fuel transfers. These emulsified sludges can cause rapid fouling and shutdown of centrifugal purifiers, clogging of strainers and filters in the fuel oil system and rapid fouling if burned in the engine.

containerships operational matters
Oil Tanker Safety Guide
Sludge tank A tank provided to receive oily residues coming from the oily water filtering or separating equipment and from the purification of fuel and lubricating oils. The sludge tank should be easy to empty and inspect. The tank height must not be less than 400mm. The tank floor should have a slope of minimum 15.

Removable Bends, Spool Pieces And Flexible Hoses

Portable bends must only be connected when required for a particular operation. On completion of that operation they must be removed and the blanks properly fitted. In order to make them conspicuous, all portable bends, and spool pieces are to be conspicuously marked and labelled with intended purpose.

Gaskets of the correct size and material are to be available, and must be used when connecting the bends, spool pieces or flexible hoses. Flexible hoses are to be pressure tested annually, marked with date/pressure and provided with test certificates as described within ISGOTT. The electrical continuity of flexible hoses is to be checked before each use should there be any doubt about condition deterioration since the last routine testing. (Otherwise every three months).

Should the hose being tested fail to meet the criteria outlined within ISGOTT, the hose must be removed from service and the office notified immediately.

As flexible hoses vary significantly in type and manufacturing methods, a retirement age should be defined for each hose type on board after consultation with the manufacturer. Upon reaching the retirement age, the hose should be removed from service, irrespective of meeting the inspection and testing criteria. The Fleet Superintendent must be notified in advance of approaching retirement dates of the flexible hoses so that replacements can be supplied.

When removable bends, spool pieces or flexible hoses are being used, particular care must be taken to ensure that they are all in respects suitable for the intended cargo.

Ship - shore Sludge discharge operation involved numerous hazards and careful consideration will need to be made for safe planning and execution. We summarized here some basic check points for safe handling. These procedures are only indicative, not exhaustive in nature and one must always be guided by practices of good seamanship

Preparation of sludge discharge plan :
  1. Has it been confirmed with the receiver that they will issue a certificate including quantity and type of sludge discharged?
  2. Has receiver confirmed they will receive the entire nominated quantity from the ship?
    sludge collecting ship at singapore
    sludge collecting ship at singapore

  3. Has an onboard meeting of the personnel overseeing transfer been held and have they been familiarized with the sludge discharge plan?
  4. Name of responsible engineer (2/A/E or 3/A/E):
  5. Name of responsible engine rating (Olr or Wpr):
  6. Are sludge discharge procedures and piping diagrams displayed at the discharge manifold?
  7. Has the sludge/bilge pump emergency stop switch been checked for operation and working?

Preparation for sludge discharge ashore:
  1. Are related valves and pipelines correctly marked for easy identification?
  2. Have all deck scuppers been plugged?
  3. Has it been confirmed that the pipeline to be used is in good condition?
  4. Has it been confirmed that the sludge transfer line is properly isolated and no other oil transfer is going on during the sludge discharge operation?
  5. Is the opposite side manifold blanked?
  6. Have appropriate light and flag signals been displayed?
  7. Is SOPEP and fire fighting equipment ready for immediate deployment?
  8. Have pumping rate & means of communication (incl. emergency) been agreed with receiver?

While starting and during discharging:
  1. Confirm no oil floating in water around the vessel?
  2. Is the sludge discharge line properly set?
  3. Confirm no leaks and the pump parameters normal?
  4. Is the reception confirmed by the receiving facility?

Confirmation after completion :
  1. Is the transfer pump stopped and line set back to normal?
  2. Has all the gear been secured back in original place and area squared up/cleaned up?
  3. Has the manifold line been blanked?
  4. Has vessel received the sludge discharge certificate and checked contents for correctness?

Further Reading

Rules of bunkering and safety onboard

Ship to ship transfer of fuel oil

Bulk liquid cargo handling - Ship to shore safety checklist

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