SC 70

SC70 Cargo tank vent systems and selection of(1985)(cont)
electrical equipment(Rev.1May 2001)(Rev.2Nov 2005)(Rev.3Oct 2010)(Rev.4Feb 2021)(Corr.1
Apr 2023)

Interpretation of Regulations SOLAS II-2/11.6.2.2 and SOLAS II-2/4.5.4.3.1 of SOLAS
Chapter II-2 as amended by IMO resolutions up to MSC.421(98)
SOLAS regulation II-2/11.6.2 reads as follows.
6.2 Openings for small flow by thermal variations
Openings for pressure release required by paragraph 6.1.1 shall:.1

have as great a height as is practicable above the cargo tank deck to obtain maximum
dispersal of flammable vapours, but in no case less than 2 m above the cargo tank deck;and.2

Be arranged at the furthest distance practicable but not less than 5 m from the nearest
air intakes and openings to enclosed spaces containing a source of ignition and fromdeck machinery and equipment which may constitute an ignition hazard. Anchor
windlass and chain locker openings constitute an ignition hazard.

For tankers constructed on or after 1 January 2017, the openings shall be arranged inaccordance with regulation 4.5.3.4.1.

Note:
1. Changes introduced in Rev.1 are to be implemented by IACS Members and Associatesfrom 1 July 2001.
2. Rev.3 of this UI is to be uniformly implemented by IACS Societies on ships contracted forconstruction on or after 1 January 2012.
3. Rev.4 of this UI is to be uniformly implemented by IACS Societies on ships contracted forconstruction on or after 1 July 2022.
4. The ‘contracted for construction’ date means the date on which the contract to build thevessel is signed between the prospective owner and the shipbuilder. For further details
regarding the date of ‘contract for construction’, refer to Procedural Requirement (PR) No.
29.

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IACS Int. 1985/Rev.4 2021/Corr.1 2023

SC 70SC70(cont)Interpretation:
Area Classification is to be carried out in accordance with the principles laid down in IEC
60092-502:1999.
A1
Areas on open deck, or semi-enclosed spaces on open deck, within 3m of cargo tankventilation outlets which permit the flow of small volumes of vapour or gas mixtures causedby thermal variation are defined as Zone 1 as specified by IEC 60092-502:1999 para 4.2.2.7.
A2
Areas within 2m beyond the zone specified in A1 above are to be considered Zone 2(as opposed to 1.5m as specified by IEC 60092-502:1999 para 4.2.3.1).
A3
Electrical equipment or cables shall not normally be installed in hazardous areas.
Where essential for operational purposes, electrical equipment may be installed inaccordance with IEC 60092-502:1999.
SOLAS regulation II-2/4.5.3.4.1 reads as follows.
.3

Not less than 10 m measured horizontally from the nearest air intakes and openings toenclosed spaces containing a source of ignition and from deck machinery and equipment
which may constitute an ignition hazard.

Interpretation:
Area Classification is to be carried out in accordance with the principles laid down in IEC
60092-502:1999.
B1
Areas on open deck, or semi-enclosed spaces on open deck, within a verticalcylinder of unlimited height and 6m radius centred upon the centre of the outlet, and within ahemisphere of 6m radius below the outlet which permit the flow of large volumes of vapour, or
gas mixtures during loading/discharging/ballasting are defined as Zone 1 as specified by IEC
60092-502:1999 para 4.2.2.8.
B2
Areas within 4m beyond the zone specified in B1 above are defined as Zone 2 as
specified by IEC 60092-502:1999 para 4.2.3.2.
B3
Electrical equipment or cables shall not normally be installed in hazardous areas.
Where essential for operational purposes, electrical equipment may be installed inaccordance with IEC 60092-502:1999.

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IACS Int. 1985/Rev.4 2021/Corr.1 2023