Clean Seas Guide for Oil Tankers, 4th Edition

The clean seas programme was introduced by the shipping industry to restrict the oiperational discharge of oil in to the sea by the retention of oil residues onboard.

The Guide, which describes the procedures used to retain oil residues onboard, is intended to help shipboard personnel comply with the oil discharge limitations that are contained in Annex 1 of MARPOL. The 1973 MARPOL convention, as amended by its 1978 Protocol, is the international instrument controlling pollution from ships. Annex 1 of the convention, which contains regulations for the prevention of pollution by oil, came into effect in October 1983.

Effective retention of oil onboard (R.O.B.) requires a thorough understanding of the procedure and the techniques required.

OCIMF/ICS strongly recommend this guide.

Under Annex I of MARPOL 73/78 what is in effect a total prohibition on the discharge of any oil (which means petroleum in any form) or oily mixture from an oil tanker, including its cargo pumproom bilges, is imposed within 50 miles of the nearest land and within certain special areas, and the flow, concentration and quantity discharged elsewhere at sea are strictly limited.

Compliance with those oil discharge limitations is achieved by adhering to procedures for the retention of oil onboard. Essentially these procedures involve the on-board collection and separation of any water and oil mixtures resulting from ballasting and tank cleaning operations. Such mixtures are accumulated in either a special slop tank, or tanks, or in a cargo tank designated as a slop tank, and are subsequently disposed of ashore at the loading or discharging port, or at a repair port. Where reception facilities are not available, the recovered oil and slops must be retained onboard, and either segregated or combined with new cargo loaded on top. In no circumstances may these residues be discharged into the sea unless the safety of the ship or its personnel is in jeopardy.

1 Procedures - The Basic Method
1.1 Basic method assumptions
1.2 Sequence of procedures
1.3 Line draining and taking on dirty ballast
1.4 tank washing
1.5 Loading clean ballast
1.6 Settling of dirty ballast
1.7 Disposal of dirty ballast
1.8 Slop tank discharge
1.9 Final line and pump flush
1.10 Discharging clean ballast
1.11 Disposal of slop residues
1.12 handling sludge
1.13 Segregated ballast tankers
1.14 Dedicated clean ballast tankers
1.15 New Marpol Annex I regulations 13f and 13g - Prevention of pollution in event of collision or stranding
1.16 Crude Oil Washing

2 Operational Factors influencing basic method
2.1 Short haul voyages
2.2 Coastal voyages
2.3 Special areas
2.4 OBO and/or Ore/oil carriers
2.5 Preparations for repair ports
2.6 Reception facilities

3 Other factors influencing basic method
3.1 General
3.2 Insufficient slop tank capacity
3.3 Interconnected slop tanks
3.4 Eductors
3.5 Slop tank heating coils
3.6 Oil/water separators and filters
3.7 Oil discharge monitor and control system
3.8 Oil/water interface detectors
3.9 Crude Oil washing
3.10 Tank cleaning chemicals
3.11 Demulsifiers

4 Responsibilities

Annex I - Water effluent cleanliness requirements, the 30 litres per mile criterion, the 1/15,000 and 1/30,000 criteria, characteristics of effluents from oil retention operations

Annex II - Special Areas

The Oil Companies International Marine Forum (OCIMF) is a voluntary association of oil companies (the ‘members’) who have an interest in the shipment and terminalling of crude oil, oil products, petrochemicals and gas. OCIMF’s mission is to be the foremost authority on the safe and environmentally responsible operation of oil tankers, terminals and offshore support vessels, promoting continuous improvement in standards of design and operation. Learn more at www.ocimf.org