What is Annex 2 of MARPOL 73/78(Regulation for the Control of Pollution by Noxious Liquid Substances in Bulk )and discharge regulations?

annex 2
Written by Amit Sharma

MARPOL Annex II Regulations for the control of pollution by noxious liquid substances in bulk sets out a pollution categorization system for noxious and liquid substances(entered into force on 6 April 1987)


Noxious liquid substances: Means any substance indicated in the pollution category column of chapter 17 or 18 of the Int. bulk chemical code or provisionally assessed under the provisions of regulations as falling into category X ,Y, or Z.

International bulk chemical code means the international code for the construction and equipment of ships carrying dangerous chemicals in bulk adopted by the Marine Environment Protection Committee of the organization.

En route means that the ship is underway at sea on a course or courses, including deviation from the shortest direct route, which as for as practicable for navigational purposes, will cause any discharge to be spread over as great an area of the sea as is reasonable and practicable.

The four categories are:
  1. Category X:

Noxious liquid substances which it discharged into the sea from tank cleaning or deballasting operation are deemed to present a major hazards to either marine sources or human health, therefore justify the prohibition of the discharge into the marine environment.

  1. Category Y:

Noxious liquid substances which if discharged into the sea from tank cleaning or deballasting operations are deemed to present a hazard to either marine resources or human health. Therefore Justify the limitation on the quality and quantity of the discharge into marine environment.

  1. Category Z:

Noxious liquid substances which if discharged into the sea from tank cleaning or deballasting operations are deemed to present a minor hazard to either marine resources or human health therefore justify less stringent restrictions on the quantity & quality of the discharge into marine environment.

  1. Other Substances:

Other Substances: substances which have been evaluated and found to fall outside Category X, Y or Z because they are considered to present no harm to marine resources, human health, amenities or other legitimate uses of the sea when discharged into the sea from tank cleaning of deballasting operations. The discharge of bilge or ballast water or other residues or mixtures containing these substances are not subject to any requirements of MARPOL Annex II.

MARPOL Annex II Special Areas:
  • Antarctic Sea
  • Black sea
  • Baltic sea
Discharge criteria for Noxious liquid substances:
  • The ship is proceeding enroute. at a speed of at least 7 knots in the case of a self propelled ships.
  • In the case of ships not self propelled at least 4 knots speed.
  • The discharge is made below the waterline through the underwater discharge outlet not exceeding the may rate the underwater discharge outlet is designed for.
  • The discharge is made at a distance not less than 12 NM from nearest land & in a depth of water of not less than 25m.
Discharge of Residues of category X:
  • A tank from which a substance in category X has been unloaded shall be prewashed before the ship leaves the port of unloading. The resulting residues shall be discharged to a reception facility until the concentration of the substance in the effluent to such facility as indicated by analysis of samples of the effluent taken by the surveyor is at or below 0.1% by weight when the required concentration level is achieved , remaining tank washings shall continue to be discharged to the perception facility until the tank is empty. Appropriate entries of these operation shall be made in the cargo record book and endorsed by the surveyor.
  • Any water subsequently introduced into the tank may be discharged into the sea in accordance with the discharge standards regulation 13.2 of this annex.
  • Exemption for a prewash : On request of the ships master an exemption for a prewash may be granted by the government of the receiving party where it is satisfied that:-
  • The unloaded tank is to be reloaded with the same substance or another substance compatible with the previous one and that the tank will not.
Procedures &Arrangement (P&A) manual:

Every ship which carry Noxious Liquefied substances of category X, Y, Z of annex II, MARPOL shall carry a procedures of arrangements manual.

Contents of P & A manual :

Section 1 :   Main features of MARPOL 73/78 Annex II.
Section 2 :  Description of ships equipments & arrangements.
Section 3 :  Cargo unloading procedures & tank stripping.
Section 4 : Procedures relating to the cleaning of cargo tanks, discharges of residues ballasting of deballasting.
Section 5 :  Information & procedures.

Addendum A :  Flow diagram
Addendum B : Pre wash procedures.
Addendum C:  Ventilation procedures
Addendum D : Additional information  & operational instruction.

Action during accidental discharge :

All preventive measured to be taken to minimize the discharge & stop from spreading.
An entry to be made in the cargo record book stating the circumstance & the reason for the discharge.
A detailed description of action to be taken to reduce or control of the discharge is written on SMPEP & a list of controls where to contact during the incident.

Cargo Record Book:

For ships carrying Noxious liquid substances in bulk. It shall record:

  1. Loading of cargo
  2. Internal transfer of cargo during voyage.
  3. Mandatory prewash in accordance with ship procedures & arrangements manual.
  4. Unloading of cargo.
  5. Cleaning of cargo tanks except mandatory wash.
  6. Discharge into the sea of tank washings.
  7. Ballasting of cargo tanks.
  8. Discharge of ballast water from cargo tanks.
  9. Accidental or other exceptional discharge.
  10. Control by authorized surveyors.

It shall be retained for a period of 3 years after the last entry has been made.
SMPEP (shipboard Marine Pollution Emergency plan) for Noxious liquid substances everything same as SOPEP.
An IOPP certificate for the carriage of Noxious liquid substances in bulk shall be issued for a period not more than 5 years.

 MARPOL Documents of Annex II :
  1. IBC Code
  2. Certificate of fitness or NLS Certificate.
  3. Officers specialized chemical tanker certificate.
  4. P & A manual approved by administration to which a particular vessel is approved.
  5. Cargo Record book.
  6. SMPEP P & A- Procedures of arrangements


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About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.