Editorial Note on Part 154
Editorial Note: Nomenclature changes to part 154 appear part 154 appear by CGD-95-072, 60 FR 50466, Sept. 29, 1995, CGD-96-041, 61 FR 50732, Sept. 27, 1996, USCG-2009-0702, 74 FR 49235, Sept. 25, 2009, and USCG-2012-0832, 77 FR 59785, Oct. 1, 2012.

§ 154.7 Definitions, acronyms, and terms. As used in this part: *“A” Class Division* means a division as defined in Regulation 3 of Chapter II-2 of the 1974 Safety Convention.
*Accommodation spaces* means public spaces, corridors, lavatories, cabins, offices, hospitals, cinemas, game and hobby rooms, pantries containing no cooking appliances, and spaces used in a similar fashion.
*Boiling point* means the temperature at which a substance's vapor pressure is equal to the atmospheric barometric pressure.
*Breadth* (B) means the maximum width of the vessel in meters measured amidships to the molded line of the frame in a ship with a metal shell and to the outer surface of the hull in a ship with a shell of any other material.
*Cargo area* means that part of the vessel that contains the cargo containment system, cargo pump rooms, cargo compressor rooms, and the deck areas over the full beam and the length of the vessel above them, but does not include the cofferdams, ballast spaces, or void spaces at the after end of the aftermost hold space or the forward end of the forwardmost hold space.
*Cargo containment system* means the arrangement for containment of the cargo including a primary and secondary barrier, associated insulation and any intervening spaces, and adjacent structure that is necessary for the support of these elements.
*Cargo service space* means space within the cargo area that is more than 2 m2 (21.5 ft.2) in deck area and used for work shops, lockers, or store rooms.
*Cargo tank* means the liquid tight shell that is the primary container of the cargo.
*Certificate of Compliance* means a certificate issued by the Coast Guard to a foreign flag vessel after it is examined and found to comply with regulations in this chapter.
*Cofferdam* means the isolating space between two adjacent steel bulkheads or decks, which could be a void space or a ballast space.
*Contiguous hull structure* includes the inner deck, the inner bottom plating, longitudinal bulkhead plating, transverse bulkhead plating, floors, webs, stringers, and attached stiffeners.
*Control space* means those spaces in which the vessel's radio, main navigating equipment, or the emergency source of power is located or in which the fire control equipment, other than firefighting control equipment under § 154.1140 to § 154.1170, is centralized.
*Design temperature* means the minimum cargo temperature the Coast Guard allows for loading, unloading, or carriage.
*Design vapor pressure* (Po) means the maximum gauge pressure at the top of the cargo tank for the design of the cargo tank.
*Document* means a Certificate of Inspection for a U.S. flag vessel or a Certificate of Compliance for a foreign flag vessel.
*Existing gas vessel* means a self-propelled vessel that— ( a ) Is delivered on or before October 31, 1976; or
( b ) Is delivered between October 31, 1976 and June 30, 1980, and is not a new gas vessel.
*Flammable cargoes* includes the following liquefied gases from Table 4 (follows § 154.1872): Acetaldehyde Butadiene Butane Butylene Dimethylamine Ethane Ethylamine Ethyl chloride Ethylene Ethylene oxide Methane (LNG) Methyl acetylene-propadiene mixture Methyl bromide Methyl chloride Propane Propylene Vinyl chloride
*Gas-dangerous space* includes the following spaces: ( a ) A space in the cargo area without arrangements to provide a safe atmosphere at all times.
( b ) An enclosed space outside the cargo area through which any piping that may contain liquid or gaseous cargo passes, or within which that piping terminates, without arrangements to prevent gas from escaping into the space.
( c ) A cargo containment system and cargo piping.
( d ) A hold space where cargo is carried in a cargo containment system: ( 1 ) With a secondary barrier; or
( 2 ) Without a secondary barrier.
( e ) A space separated from a hold space under paragraph (d)(1) of this definition by a single gastight boundary.
( f ) A cargo pumproom and a cargo compressor room.
( g ) A zone on the weather deck or a semi-enclosed space on the weather deck within 3.05 m (10 ft) of any cargo tank outlet, gas or vapor outlet, cargo pipe flange, cargo valve, or of entrances and ventilation openings to a cargo pump room or a cargo compressor room.
( h ) Except for existing gas vessels, the weather deck over the cargo area and 3.05 m (10 ft) forward and aft of the cargo area on the weather deck to 2.4 m (8 ft) above the weather deck.
( i ) A zone within 2.4 m (8 ft) of the outer surface of a cargo containment system where the surface is exposed to the weather.
( j ) An enclosed or semi-enclosed space in which there is piping containing cargo, except those— ( 1 ) With gas sampling lines for gas detection equipment under § 154.1350(n); or
( 2 ) In which boil-off gas is used as fuel under § 154.703.
( k ) A space for storage of cargo hoses.
( l ) An enclosed or semi-enclosed space having an opening into any gas-dangerous space or zone.
*Gas-safe space* means a space that is not a gas-dangerous space.
*Hold space* means the space enclosed by the vessel's structure in which there is a cargo containment system.
*IMO* stands for the lnternational Maritime Organization.
*IMO Certificate* means a Certificate of Fitness for the Carriage of Liquefied Gases in Bulk issued under the IMO— ( a ) “Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk”, adopted November 12, 1975 by Assembly Resolution A.328(IX), as amended;
( b ) “Code for Existing Ships Carrying Liquefied Gases in Bulk”, adopted November 12, 1975, as amended; or
( c ) “Recommendations Concerning Ships Not Covered by the Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk”, (Resolution A.328(IX)), adopted November 12, 1975 by Assembly Resolution A.329(IX).
*Independent tank* is a cargo tank that is permanently affixed to the vessel, is self-supporting, and is not part of the hull or essential to the strength or integrity of the hull.
*Independent tank type A* is an independent cargo tank designed primarily using classification society classical ship structural analysis procedures.
*Independent tank type B* is an independent cargo tank designed from model tests, refined analytical tools, and analysis methods to determine stress levels, fatigue life, and crack propagation characteristics.
*Independent tank type C* (pressure tank) is an independent cargo tank meeting pressure vessel criteria where the dominant stress producing load is design vapor pressure.
*Insulation space* means a space, that could be an interbarrier space, occupied wholly or in part by insulation.
*Integral tank* means a cargo tank that is a structural part of the vessel's hull and is influenced in the same manner and by the same loads that stress the adjacent hull structure.
*Interbarrier space* means the space between a primary and a secondary barrier, with or without insulation or other material.
*Length (L)* is ninety-six percent of the total length in meters on a waterline at eighty-five percent of the least molded depth measured from the top of the keel or the length from the foreside of the stem to the axis of the rudder stock on the waterline, whichever is greater. In vessels having a rake of keel, the waterline is parallel to the design waterline.
*Liquefied gas* means a cargo having a vapor pressure of 172 kPa (25 psia) or more at 37.8 °C (100 °F).
*MARVS* stands for the Maximum Allowable Relief Valve Setting.
*Membrane tank* is a cargo tank that is not self-supporting and consists of a thin layer (membrane) supported through insulation by the adjacent hull structure.
*New gas vessel* means a self-propelled vessel that— ( a ) Is constructed under a building contract awarded after October 31, 1976;
( b ) In the absence of a building contract, has a keel laid or is at a similar stage of construction after December 31, 1976;
( c ) Is delivered after June 30, 1980; or
( d ) Has undergone a major conversion for which— ( 1 ) The building contract is awarded after October 31, 1976;
( 2 ) In the absence of a building contract, conversion is begun after December 31, 1976; or
( 3 ) Conversion is completed after June 30, 1980.
*Primary barrier* means the inner boundary that contains the cargo when the cargo containment system includes two boundaries.
*Process pressure vessel* means a pressure vessel that is used in a reliquefaction, cargo heating, or other system that processes cargo.
*Remote group alarm* means an audible and visual alarm that alerts when an alarm condition exists but does not identify that condition.
*Secondary barrier* means the liquid resisting outer boundary of a cargo containment system when the cargo containment system includes two boundaries.
*Semi-membrane tank* is a cargo tank that is not self-supporting and that can expand and contract due to thermal, hydrostatic, and pressure loadings. It consists of flat surfaces, supported through insulation by the adjacent hull structure, and shaped corners that connect the flat surfaces.
*Service space* means a space outside the cargo area that is used for a galley, pantry containing cooking appliances, locker or store room, workshop except those in machinery spaces, and similar spaces and trunks to those spaces.
*Shut-off valve* is a valve that closes a pipeline and provides nominal metal to metal contact between the valve operating parts, including the disc and gate, and the valve body.
*Specific gravity* (p) means the ratio of the density of the cargo at the design temperature to the density of water at 4 °C (39 °F).
*Tank cover* is the structure protecting those parts of the cargo containment system that protrude through the weather deck and providing continuity to the deck structure.
*Tank dome* means the uppermost portion of the cargo tank. For below deck cargo containment systems, it means the uppermost portion of the cargo tank that protrudes through the weather deck or through the tank cover.
*Toxic cargoes* includes the following liquefied gases from Table 4 (follows § 154.1872): Acetaldehyde Ammonia, anhydrous Dimethylamine Ethylamine Ethyl chloride Ethylene oxide Methyl bromide Methyl chloride Sulfur dioxide Vinyl chloride
*Vapor pressure* means the absolute equilibrium pressure of the saturated vapor above the liquid, expressed in kPa (psia), at a specific temperature.
*Void space* means an enclosed space in the cargo area outside of the cargo containment system, except a hold space, ballast space, fuel oil tank, cargo pump or compressor room, or any space used by personnel.
*1974 Safety Convention* stands for the International Convention on Safety of Life at Sea, 1974, done at London, November 1, 1974.