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Marpol Annex I Part A

This page introduces the main features of Marpol Annex I Part A, which regulates discharges from machinery spaces of all ships over 400gt. It then explores the Annex in greater detail from the ship's master perspective.

notes on marpol annex i part a

What is Marpol Annex I Part A and what subjects and ship types does it cover?

Annex I contains regulations for the protection of the marine environment from oil pollution in both operational and accidental discharges from ships at sea.

The Annex originally entered into force on the 2nd October 1983 but was amended in 1992 to make double-hull construction mandatory for all newly-built oil tankers.

The current version of the Annex was revised and came into force on 1st January 2007.

Annex I applies to all ships greater than 400gt, and all oil tankers greater than 150gt.

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How is "oil" defined by Annex I?

Within the context of Marpol Annex I Part A, oil means petroleum in any form which includes:

  • crude oil
  • fuel oil
  • sludge
  • oil refuse
  • refined products (other than those petrochemicals subject to the provisions of Annex II)
  • substances listed in appendix I to the Annex.

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Which statutory certificate is required under Marpol Annex I Part A?

Marpol Annex I mandates that oil tankers of 150gt and above and all ships of 400gt and above must hold a valid International Oil Pollution Prevention Certificate to certify that they have been successfully surveyed following the requirements of the Annex.

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Some requirements of the Marpol Annex I Part A

The regulations in Annex I can be divided into the requirements covering two broad categories:

  1. Control of operational discharge of oil from the machinery spaces of all ships, and
  2. Control of operational discharge of oil from the cargo areas of oil tankers.

Regulations on the machinery spaces of all ships include:

  • control of operational discharges of oily bilge water from machinery space outside Special Areas
  • operation of oily bilge water discharge monitoring equipment
  • recording of machinery space operations concerning oil in the Oil Record Books Part 1 (ORB1)
  • recording and disposal of waste oil sludge
  • prohibition of discharge of oily waste in Special Areas
  • requirement to maintain SOPEP on board

Requirements for the operational discharge of oil from the cargo areas of oil tankers cover:

  • double-bottom construction of oil tankers
  • oil discharge monitoring and control systems
  • slop tanks
  • bottom protection of pump rooms
  • discharge of tank washing.

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What are the requirements for the discharge of oil from machinery spaces of all ships outside special areas?

Annex I states that any discharge of oily mixtures into the sea from ships of 400gt and above is prohibited unless under the following conditions:

  1. The ship is proceeding ‘en route’.
  2. The oil content of the undiluted effluent does not exceed 15 parts per million.
  3. The oily mixture is processed through oil filtering equipment.
  4. The oily mixture does not originate from the cargo pumproom bilges on oil tankers.
  5. With oil tankers, the oily mixture is not mixed with oil cargo residues.
  6. The vessel is not in a Special Area.

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What are the requirements for the control of operational discharge of oil within special areas?

Any discharge into the sea of oil or oily mixtures from ships of 400gt and above is prohibited unless all the following conditions are satisfied:

  1. The ship is proceeding "en route".
  2. The effluent oil content without dilution does not exceed 15 parts per million.
  3. The oily mixture is processed through oil filtering equipment equipped with an alarm and automatic stopping device to divert the discharge into a tank on board if the 15ppm limit is exceeded.
  4. The oily mixture does not originate from cargo pump room bilges on oil tankers.
  5. In oil tankers, the oily mixture is not mixed with oil cargo residues.

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When is a vessel considered to be 'en-route' under Marpol Annex I?

Given the Marpol Annex, they offer no guidance on the terms or in its practical application.

Instead, the ship's master must refer to Annex II, where the definition is provided instead:

En route means that a ship meets the following conditions:

  • is underway at sea
  • is on a course or courses (including deviation from the shortest direct route), which, as far as practicable for navigation
  • will cause any discharge to be spread over as great an area of the sea as is reasonable and navigationally practicable

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Special Areas under MARPOL Annex I

'Special Areas' are areas of the sea where, due to officially recognised oceanographical and ecological conditions and to the particular character of sea traffic, special methods to prevent pollution by oil are compulsory.

For Annex I, the ten Special Areas are defined as:

  1. The Mediterranean Sea
  2. The Baltic Sea
  3. The Black Sea
  4. The Red Sea
  5. The Gulfs
  6. The Gulf of Aden
  7. The Antarctic area
  8. The North-West European waters including the North Sea and its approaches, the Irish Sea and its approaches, the Celtic Sea, the English Channel and its approaches, and part of the North-East Atlantic immediately to the west of Ireland
  9. The Oman area of the Arabian Sea
  10. Southern South African waters

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What are the requirements for discharges in Antarctic waters?

Under Marpol Annex I Part A, the discharge into the sea of oil or oily mixtures from any ship shall be prohibited in the Antarctic area.

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What are the requirements regarding oil filtering equipment?

All ships of 400gt and above shall be fitted with oil filtering equipment.

Oil filtering equipment must:

  • be of a design approved by the administration
  • ensure that any oily mixture discharged into the sea after passing through the system has an oil concentration not exceeding fifteen parts per million
  • incorporate an alarm showing when this oil concentration cannot be achieved
  • be provided with arrangements to ensure that any discharge of oily mixtures is automatically stopped when the oil content of the effluent exceeds 15ppm

(For further information, please see IMO Res. MEPC 107 (49))

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Which operations must be recorded in the Oil Record Book Part 1 operations are required to be - ‘Machinery Space Operations’ (ORB1)?

Any oil tanker of 150gt or above and any ship of 400gt or above (excluding oil tankers) must have an ORB1.

The ORB1 should be in the form specified in this Annex.

The ORB1 should be completed on a tank-to-tank basis if appropriate when any of the following operations take place on board the ship:

  1. overboard discharge of oily water accumulated in machinery bilge spaces
  2. bunkering of fuel or bulk lube oil
  3. ballasting or cleaning of oil fuel tanks
  4. discharge of dirty ballast/cleaning water from oil fuel tanks
  5. collection and disposal of oil sludge residues

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What other events must be recorded within ORB1?

In addition to the operations listed above, the ORB1 should also be modified to record the following events:

  • accidental or exceptional discharge of oil or oily mixture (the ORB1 statement must include the circumstances of the discharge)
  • failure of the oil filtering equipment required by Marpol Annex I

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Where should the ORB1 be kept?

ORB1 should be retained on board and readily available for inspection at all reasonable times except with unmanned ships under tow, shall be kept on board the ship.

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How long should historic ORB1 records be retained on board the ship?

ORB1 should be preserved for a minimum of three years from the last entry

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