IMO: Revised Unified interpretations of SOLAS chapter II-2

The International Maritime Organization has published the revised Unified interpretations of SOLAS chapter II-2.

Circular MSC.1/Circ.1276/Rev.1 was published on 27 June 2023 and supersedes MSC.1/Circ.1276.

Introduction

The Maritime Safety Committee, at its eighty-fourth session (7 to 16 May 2008), with a view to providing more specific guidance for application of the relevant requirements of the 1974 SOLAS Convention, approved the Unified interpretations of SOLAS chapter II-2 prepared by the Sub-Committee on Fire Protection, at its fifty-second session (14 to 18 January 2008).

The Maritime Safety Committee, at its 107th session (31 May to 9 June 2023), approved draft amendments to the unified interpretations of regulations II-2/9.7.2 and 9.7.5 on separation of ducts from spaces, in order to align them with the provisions of the SOLAS Convention, as amended by resolution MSC.365(93), prepared by the Sub-Committee on Ship Systems and Equipment at its ninth session (27 February to 3 March 2023), as set out in the annex.

Member Governments are invited to use the annexed revised unified interpretations as guidance when applying relevant provisions of SOLAS chapter II-2 to fire protection construction, installation, arrangements and equipment to be installed on board ships of which the building contract is placed on or after 5 June 2023, and to bring the unified interpretations to the attention of all parties concerned.

Annex: Revised Unified interpretations of SOLAS chapter II-2

Regulation II-2/4.3 – Arrangements for gaseous fuel for domestic purposes

A portion of open deck, recessed into a deck structure, machinery casing, deck house, etc., utilized for the exclusive storage of gas bottles is considered acceptable for the purpose of regulation II-2/4.3 provided that:

.1 Such a recess has an unobstructed opening, except for small appurtenant structures, such as opening corner radii, small sills, pillars, etc. The opening may be provided with grating walls and door; and
.2 The depth of such a recess is not greater than 1 m.

A portion of open deck meeting the above should be considered as open deck in applying tables 9.1 to 9.8 of SOLAS chapter II-2.

Regulations II-2/9.7.2 and 9.7.5 – Separation of ducts from spaces

With respect to the application of SOLAS regulations II-2/9.7.2 and 9.7.5 for determining fire insulation for trunks and ducts which pass through an enclosed space, the term "pass through" pertains to the part of the trunk/duct contiguous to the enclosed space.

The following sketches are given as examples:

Regulation II-2/10.5.6 – Fixed local application fire-extinguishing systems*

*The fixed local application fire-fighting systems shall be approved based on the standards contained in the Guidelines for the approval of fixed water-based local application fire-fighting systems for use in category A machinery spaces (MSC/Circ.913), as was superseded by MSC.1/Circ.1387.

The end nozzles of a single line of nozzles should be positioned:

.1 outside the hazard where paragraph 3.4.2.1 of the appendix to the annex to MSC/Circ.913 is applicable, to the distance established in testing; and
.2 at the edge or outside of the protected area where paragraph 3.4.2.2 of the appendix to the annex to MSC/Circ.913 is applicable.

A single nozzle should be located above the fire source and at the centre of an area having dimensions D/2 x D/2.

Sketches of acceptable arrangements are as follows:

System (utilizing a 3 x 3 nozzle grid) that extinguishes fires referred to in paragraphs 3.3.2.1 to 3.3.2.3 of the appendix to the annex to MSC/Circ.913.

For this system, the outer nozzles should be installed outside of the protected area at a distance of at least 1/4 of the maximum nozzle spacing.

System (utilizing a 3 x 3 nozzle grid) that extinguishes fires referred to in paragraphs 3.3.2.3 to 3.3.2.5 of the appendix to the annex to MSC/Circ.913

For this system, outer nozzles can be located either at the edge of the protected area or outside of the protected area.

System (utilizing a 2 x 2 nozzle grid) that extinguishes fires referred to in paragraphs 3.3.2.3 to 3.3.2.5 of the appendix to the annex to MSC/Circ.913

For this system, outer nozzles can be located either at the edge of the protected area or outside of the protected area.

A single row of nozzles

System that extinguishes fires referred to in paragraphs 3.3.2.3 to 3.3.2.5 of the appendix to the annex to MSC/Circ.913

For this system, outer nozzles should be placed at least at the edge of the protected area.

System that extinguishes fires referred to in paragraphs 3.3.2.1 to 3.3.2.3 of the appendix to the annex to MSC/Circ.913

For this system, the outer nozzles should be placed outside of the protected area at a distance of at least 1/4 of the maximum nozzle spacing.

Single nozzle

Regulation II-2/10.8.1 − Fixed deck foam fire-extinguishing systems

Where an enclosed pipe trunk is situated within the cargo tanks deck area, the pipe trunk:

.1 Should be protected by a fixed fire-extinguishing system in accordance with regulation II-2/10.9; and the extinguishing system should be operated from a readily accessible position outside the pipe trunk.
.2 Is not considered part of the cargo tanks deck area.
.3 The area of the pipe trunk need not be included in the calculation of the foam solution rate of supply for the deck foam system required by regulation II-2/10.8.
.4 Should be adequately ventilated and protected in accordance with regulations II-2/4.5.10.1.2 and II-2/4.5.10.1.3; and
.5 Should contain no flammable gas sources other than pipes and flanges. If the pipe trunk contains any other source of flammable gas, i.e. valves and pumps, it should be regarded as a cargo pump-room.

For more information, please see the document below (available only to subscribers):