Regulations on Segregated Ballast Tanks

         Regulation on Segregated Ballast tanks comes under MARPOL Annex-I, Chapter 4 - Requirements for the Cargo Area of Oil Tankers, Part A - Construction, Regulation 18.

Oil Tankers of 20,000 tonnes deadweight and above delivered after 1 June 1982:

Paragraph 1:

• Every Crude Oil tanker of 20,000 tonnes deadweight and above and every product carrier of 30,000 tonnes deadweight and above delivered after 1 June 1982 shall be provided with segregated ballast tanks and shall comply with this regulation. 

Paragraph 2:

• The capacity of the SBT shall be so determined that the ship may operate safely on ballast voyages without resource to the use of cargo tanks for water ballast except as provided in paragraph 3 or 4 of this regulation.

• The capacity of SBT shall be at least such that, in any ballast condition at any part of the voyage, including the conditions of lightweight plus segregated ballast only, the ship's draught and trim can meet the following requirements.

1. The moulded draught amidships (dm) in metres shall not be less than dm = 2.0 + 0.02 L
2. The draughts at the forward and aft perpendicular shall correspond to those determined by the dm under the trim by the stern of not greater than 0.015L.
3. In any case, the draught at the after perpendicular shall not be less than that which is necessary to obtain full immersion of the propeller(s).  

Paragraph 3:

• In no case shall ballast water be carried in cargo tanks, except:

1. On rare voyages when weather conditions are so severe that, in the opinion of the master, if necessary to carry additional ballast water in cargo tanks for the safety of the ship.
2. In exceptional cases where the particular character of the operation of an oil tanker renders it necessary to carry ballast water above the quantity as required under paragraph 2 of this regulation.
3. Such additional ballast water shall be processed and discharged in compliance with regulation 34 of this Annex and an entry shall be made in Oil Record Book Part II.

Paragraph 4:

• In the case of crude oil tankers, the additional ballast permitted in paragraph 3 of this regulation shall be carried in cargo tanks only if such tanks have been crude oil washed before departure from an oil unloading port or terminal.

Paragraph 5:

• Regardless of the provisions of paragraph 2 of this regulation the segregated ballast conditions for oil tankers less than 150 metres in length shall be to the satisfaction of the Administration.

Crude Oil Tankers of 40,000 tonnes deadweight and above delivered on or before 1 June 1982:

• Every crude oil tanker of 40,000 tonnes deadweight and above delivered on or before 1 June 1982, shall be provided with SBT and shall comply with the requirements of paragraphs 2 and 3 of this regulation.

• Oil tankers  of 40,000 tonnes deadweight and above which are fitted with CBT (Clean Ballast Tank) and COW (Crude Oil Washing) and designated as "crude oil/product carriers" in the supplement to the IOPP Certificate operate as follows:
• They should operate with CBT and neither crude oil nor product oil should be carried in dedicated CBT.
• When carrying a complete or partial cargo of crude oil they should, in the cargo-carrying tanks, also operate with COW for sludge control.
• Approved procedures by the Administration for the changeover between COW and CBT modes on the tanker with common or separate independent piping and pump arrangements for cargo and (CBT) ballast handing should be continuously acceptable as long as the carriage of crude oil in CBT mode is not given as permissible.

Product Carriers of 40,000 tonnes deadweight and above delivered on or before 1 June 1982:

• Every product carrier of 40,000 tonnes deadweight and above delivered on or before 1 June 1982, shall be provided with SBT and shall comply with the requirements of paragraphs 2 and 3 of this regulation, or alternatively operate with dedicated CBT in accordance with the following provisions:
• The product carrier shall have adequate tank capacity, dedicated solely to the carriage of clean ballast to meet the requirements of paragraphs 2 and 3 of this regulation.
• The arrangements and operational procedures for dedicated CBT shall comply with the requirements established by the Administration.
• The product carrier shall be equipped with an oil content meter, approved by the Administration on the basis of the specifications recommended by the organization, to enable supervision of the oil content in ballast water being discharged.
• Every product carrier operating with dedicated CBT shall be provided with a Dedicated CBT Operation Manual detailing the system and specifying operational procedures, such a manual shall be to the satisfaction of the Administration.
• If an alteration affecting the dedicated CBT system is made, the Operation Manual shall be revised accordingly.

Oil tankers delivered on or before 1 June 1982 having special ballast arrangements:

• Oil tankers delivered on or before 1 June 1982, is so constructed or operates in such a manner that it complies at all times with the draught and trim requirements set out in paragraph 2 of this regulation without resources to the use of ballast water, it shall be deemed to comply with the SBT requirements of this regulation, provided that all of the following conditions are complied with:   
• Operational procedures and ballast arrangements are approved by Administration.  
• The agreement is reached between the Administration and the Governments of the port state parties to the present convention concerned when the draught and trim requirements are achieved through operational requirements.
• The International Oil Pollution Prevention Certificate (IOPP) is endorsed to the effect that the oil tanker is operating with special ballast arrangements.   
• In no case shall ballast water be carried in oil tanks except on rare voyages when weather conditions are so severe that, in the opinion of the master, if necessary to carry additional ballast water in cargo tanks for the safety of the ship.
• Such additional ballast water shall be processed and discharged in compliance with regulation 34 of this Annex and an entry shall be made in Oil Record Book Part II.

Oil tankers of 70,000 tonnes deadweight and above delivered after 31 December 1979:

• Oil tankers of 70,000 tonnes deadweight and above delivered after 31 December 1979, shall be provided with SBT and shall comply with paragraphs 2, 3 and 4 or paragraph 5 as appropriate of this regulation.

Reference: IMO Publications & Documents - International Conventions - MARPOL - Annex I