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Tanker operation : Restriction of carriage and discharging of oil and water ballast

Due to the nature of trade oil tankers often have to run a considerable distance with empty cargo tanks. Ballast water is essential to ensure safety during such empty voyages. Ballast water is used to compensate for the overall weight distribution of a ship and to keep her float safely, remain upright in a stable condition. It helps to maintain stability under different cargo loads during loading and unloading operations. For better maneuverability, any vessel may need to adjust her ballast.

Onboard an oil tanker during cargo operations requires some careful consideration for ballast water taking in or out. The provision of MARPOL 73/78, ANNEX I implies restriction of Loading Water Ballast into any cargo tanks. Dedicated ballast tanks, therefore, strictly maintained for ballasting operation. However, the annex I explained ballast might only be carried in cargo oil tanks or fuel oil tanks if necessary in order to prevent severe structural damage (e.g., Heavy weather), or to prevent human casualties or loss of human life.



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Oil Tanker Safety Guide
Control Of Discharge Of Oil Or Oily Mixture

Cargo oil or oily mixtures should never be discharged into the marine environment unless such discharge of oil is a result of structural damage to the vessel or its equipment failure. In all cases of accident, reasonable precautions should be taken as soon as possible, to prevent the discharge of oil and make the best effort to minimize damage to the marine environment. In some cases, a discharge may become necessary to prevent serious structural damage and risk of more spillage of oil or to prevent serious casualties or the loss of human life. For routine shipboard operations, oily water mixtures may be discharged only when the latest discharge criteria as per MARPOL ANNEX I satisfied in all respects.

oil tanker golden victory underway
Oil tanker underway

Where Oil or Oily Mixture (Washing Water, Bilge, and Ballast Water that Contains Cargo Oil) in the Cargo Tank Area (including the Pump Room) is discharged according to the Provisions of Article For discharge of bilge and other oil in the machinery space, follow the Procedures for Treatment of Waste Oil and Oily Bilge


Control Of Discharge Of Oily Mixture Originating From Cargo Oil From Tankers

In Special Areas as defined in the latest revision of MARPOL 73/78 Annex I, discharge is prohibited, except segregated or clean ballast water, as governed under MARPOL ANNEXE I

Other Waters than Special Areas, discharge is only permitted under the latest revision of MARPOL 73/78 ANNEX I

Method of Discharge Segregated Ballast: Segregated ballast water may be discharged below the waterline after the water surface has been inspected and found free from oil at the starting of operation. The ballast water may be released by the use of ballast pumps or by gravity while in port, at offshore terminals, or sea. The local requirement for ballast water treatment (Management) should be complied with. Take adequate measures to prevent water hammering, especially at the start of the operation.


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