New Unified Interpretations under MARPOL Annex I

The International Maritime Organization’s (IMO) Marine Environment Protection Committee 56th session (MEPC 56) agreed on two new Unified Interpretations on recent regulations under MARPOL Annex I. Both proposals were suggested by the International Association of Classification Societies (IACS).


Oil Fuel Tank Protection


IACS, in document MEPC 56/6 invited MEPC 56 to a new Unified Interpretation, relating to the implementation of MARPOL Annex I new regulation 12A on oil fuel tank protection which would enter into force on 1 August 2007 for ships delivered on or after 1 August 2010. The proposed Unified Interpretation has three main elements as follows:


a)  the requirement in regulation 12A.9 for valves (of oil fuel tanks) to be located “within or immediately adjacent to the oil fuel tank” be treated in a similar manner

as that for suction wells, which as per regulation 12A.10, are allowed to protrude into the double bottom up to a distance h/2 from the bottom shell plating;

b) valves for oil fuel tanks which are allowed at a distance less than h or w from the ship’s bottom or side, as per alternative regulation 12A.11 (accidental oil fuel

outflow performance), may also be arranged at the distance less than h or w respectively; and

c) fuel air escape pipes and overflow pipes are not to be considered as part of “lines of fuel oil pining” and therefore may be located at a distance from the ship’s side less than w.


MEPC agreed to adopt this Unified Interpretation but, as requested by India, this will also be applicable to oil tanker cargo tanks under regulation 25.3.3 of MARPOL Annex I.


Pump-room bottom protection


MEPC 56 has also adopted a revised version of the Unified Interpretation 41 applicable to regulation 22 of MARPOL Annex I on pump-room bottom protection.


The improvement consists of adding specifications relating to the size and location of bilge wells, which now were not mentioned in the regulation itself, in line with parallel regulations of MARPOL Annex I (regulations 19.3.5 for suction wells in cargo tanks; 12A10 for suction wells in oil fuel tanks; and 23.4.6 for suction wells in oil tanks). The proposed revised UI 41 can be seen in the document submitted by IACS MEPC 56/6/5


Contact: Dragos Rauta