12.1 Goal
The goal of this chapter is to provide for the prevention of explosions and for the
limitation of effects from explosion.
12.2 Functional requirements
This chapter is related to functional requirements in 3.2.2 to 3.2.5, 3.2.7, 3.2.8,
3.2.12 to 3.2.14 and 3.2.17. In particular the following apply:
The probability of explosions shall be reduced to a minimum by:
- .1 reducing number of sources of ignition; and
- .2 reducing the probability of formation of ignitable mixtures.
12.3 Regulations – General
12.3.1 Hazardous areas on open deck and other spaces not addressed in
this chapter shall be decided based on a recognized standard.footnote The electrical equipment fitted within
hazardous areas shall be according to the same standard.
LR 12.3-01 A hazardous areas classification study is to be
undertaken. The objective of the study is to identify areas or spaces in which a
flammable/explosive atmosphere is present or may be expected to be present, such
that potential sources of ignition can be eliminated or controlled, and access to
such areas restricted.
LR 12.3-02 The scope of the hazardous areas classification study
is to consider all machinery and equipment which could represent a source of release
of flammable/explosive gas in:
(a) normal operation, start-up, normal shutdown, non-use, and emergency
shutdown of the fuel-gas system;
(b) equipment intended for recovery from unintended releases of gas
(e.g. venting systems).
LR 12.3-03 The hazardous areas classification study is to be
undertaken:
(a) to identify and categorise areas in which a hazardous atmosphere is
present or may occur using International Standard IEC 60079-10-1, Explosive
atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres or
another standard acceptable to LR;
(b) to identify mechanical equipment appropriate for use in a hazardous
area using International Standard EN 13463-1, Non-electrical equipment for use in
potentially explosive atmospheres or another standard acceptable to LR.
12.3.2 Electrical equipment and wiring shall in general not be installed
in hazardous areas unless essential for operational purposes based on a recognized
standard.footnote
LR 12.3-04 Electrical equipment and components intended for use in
hazardous areas are to be of a certified type in accordance with Pt 6, Ch 2,14 of the Rules for Ships or an acceptable and
relevant National Standard.
LR 12.3-05 Mechanical equipment and components intended for use
in a hazardous area are to be designed, constructed and installed to ensure that
they are:
(a) suitable for operation in normal or foreseeable hazardous
conditions;
(b) suitable for operation in a hazardous atmosphere that may be
produced or released by the components or equipment; and
(c) suitable for operation in hazardous atmospheres, taking into account
the nature of every electrical and non-electrical source of ignition.
LR 12.3-06 Equipment which may produce hot particles or hot
surfaces and which is intended to be located less than 3,5 m above a hazardous area
is to be either totally enclosed or provided with suitable guards or screens to
prevent ignition sources falling into the hazardous area.
LR 12.3-07 Low-pressure sodium vapour discharge lamps are not to
be installed above a hazardous area.
LR 12.3-08 Where insulating materials are used to protect against
the effects of high surface temperatures, they are to prevent the ingress of
gas.
12.3.3 Electrical equipment fitted in an ESD-protected machinery space shall fulfil
the following:
- .1 in addition to fire and gas hydrocarbon detectors and fire and gas alarms,
lighting and ventilation fans shall be certified safe for hazardous area zone 1;
and
- .2 all electrical equipment in a machinery space containing
gas-fuelled engines, and not certified for zone 1 shall be automatically
disconnected, if gas concentration above 40% LEL is detected by two detectors in
the space containing gas-fuelled consumers.
12.4 Regulations on area
classification
12.4.1 Area classification is a method of analysing and classifying the
areas where explosive gas atmospheres may occur. The object of the classification is
to allow the selection of electrical apparatus able to be operated safely in these
areas.
12.4.2 In order to facilitate the selection of appropriate electrical
apparatus and the design of suitable electrical installations, hazardous areas are
divided into zones 0, 1 and 2.footnote See also 12.5 below.
LR 12.4-01 The requirements of 12.4.2 are also to be applied for
the selection of appropriate mechanical equipment and the design of mechanical
installations.
12.4.3 Ventilation ducts shall have the same area classification as the ventilated
space.
12.5 Hazardous area zones
LR 12.5-01 The hazardous areas identified in 12.5.2 and 12.5.3
are only valid for the following assumptions. If either (a) or (b) is not met,
hazardous areas are to be determined in accordance with LR 12.3-03:
(a) ventilation is supplied: at least 30 air changes per hour;
(b) gas supply pressure does not exceed 10 bar.
12.5.1 Hazardous area zone 0
This zone includes, but is not limited to the interiors of fuel tanks,
any pipework for pressure-relief or other venting systems for fuel tanks, pipes and
equipment containing fuel.
12.5.2 Hazardous area zone 1footnote
This zone includes, but is not limited to:
- .1 tank connection spaces, fuel storage hold spacesfootnote and interbarrier spaces;
LR 12.5-02 For the purposes of hazardous area classification, fuel
storage hold spaces containing Type C tanks with all potential leakage sources in a
tank connection space and having no access to any hazardous area, shall be
considered non-hazardous.
LR 12.5-03 Where the fuel storage hold spaces include potential
leak sources, e.g. tank connections, they shall be considered hazardous area zone
1.
LR 12.5-04 Where the fuel storage hold spaces include bolted
access to the tank connection space, they shall be considered hazardous area zone
2.
- .2 fuel preparation room arranged with ventilation according to
13.6;
- .3 areas on open deck, or semi-enclosed spaces on deck, within 3 m
of any fuel tank outlet,footnote gas or vapour outlet, bunker manifold
valve, other fuel valve, fuel pipe flange, fuel preparation room ventilation
outlets and fuel tank openings for pressure release provided to permit the flow
of small volumes of gas or vapour mixtures caused by thermal variation;
- .4 areas on open deck or semi-enclosed spaces on deck, within 1.5
m of fuel preparation room entrances, fuel preparation room ventilation inlets
and other openings into zone 1 spaces;
- .5 areas on the open deck within spillage coamings surrounding gas
bunker manifold valves and 3 m beyond these, up to a height of 2.4 m above the
deck;
- .6 enclosed or semi-enclosed spaces in which pipes containing fuel
are located, e.g. ducts around fuel pipes, semi-enclosed bunkering stations;
- .7 the ESD-protected machinery space is considered a non-hazardous
area during normal operation, but will require equipment required to operate
following detection of gas leakage to be certified as suitable for zone 1;
- .8 a space protected by an airlock is considered as non-hazardous
area during normal operation, but will require equipment required to operate
following loss of differential pressure between the protected space and the
hazardous area to be certified as suitable for zone 1; and
- .9 except for type C tanks, an area within 2.4 m of the outer
surface of a fuel containment system where such surface is exposed to the
weather.
LR 12.5-05 In addition to the areas defined in 12.5.2, hazardous
area zone 1 also includes:
(a) enclosures or compartments containing gas regulating and block and
bleed valves;
(b) areas on open deck or semi-enclosed spaces on deck, within 3 m of
ventilation outlets of spaces identified in 12.5.2.1 and 12.5.2.6 and LR 12.5-02
(a);
(c) areas on open deck or semi-enclosed spaces on deck within the
vicinity of any gas tank outlet intended for the passage of large volumes of gas or
vapour (e.g. fuel containment pressure relief valves); this hazardous area is
defined as a vertical cylinder clear of obstructions and 6 m radius centred upon the
centre of the outlet and within a hemisphere of 6 m radius below the outlet.
12.5.3 Hazardous area zone 2footnote
12.5.3.1 This zone includes, but is not limited to areas within 1.5 m surrounding
open or semi-enclosed spaces of zone 1.
12.5.3.2 Space containing bolted hatch to tank connection space.
LR 12.5-06 In agreement with the National Administration, time
restricted access to the tank connection space via a bolted hatch in a non-hazardous
space may be considered in accordance with EN 60079 (A2.2 Opening classification).
LR 12.5-07 In addition to the areas defined in 12.5.3.1 and
12.5.3.2, hazardous area zone 2 also includes:
(a) areas 4 m beyond the cylinder and 4 m beyond the sphere defined in
LR 12.5-02 (c);
(b) areas 3 m beyond the areas in 12.5.2.4 up to a height of 2,4 m above
the deck;
(c) air-locks protecting a non-hazardous area from a zone 1 area.
LR 12.5-08 Hazardous areas associated with the use of integral
structural fuel containment systems are to be specially considered.
LR 12.5-09 Hazardous area classification of the fuel storage hold
space is to be specially considered with regard to the access arrangements to the
tank connection space and the presence of any equipment and openings which could
present a source of gas release.