Part V

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Additional Requirements for Flammable Cryogenic Liquid Carriers

Scope

24. (1) The design and operational characteristics of tank, cargo handling and related systems on vessels carrying flammable cryogenic liquid cargoes must be fully appreciated by the marine chemist where he makes the determinations required by section 8; this Part describes the conditions required before repairs are made in spaces that have carried, or have been exposed to, flammable cryogenic liquid cargoes as liquids or vapors.

(2) This Part supplements the factors to be considered prior to issuance of the marine chemist's certificate as in section 8.

Interpretation

25. The following definitions apply.

"cargo area" means that part of the ship with the cargo containment system and cargo pump and compressor rooms; it includes deck areas over the full beam and length above this part of the ship; the cofferdams, ballast, or void spaces at the after end of the aftermost hold space or the forward end of the forwardmost hold space are excluded from the cargo area.

"cargo containment system" means the arrangement for containment of cargo, including any primary and secondary barriers, associated insulation, and any intervening spaces and adjacent structure for the support of these elements; if the secondary barrier is part of the hull structure it may be a boundary of the hold space.

"cryogenic liquid" means a refrigerated liquefied gas having a boiling point colder than -90 degrees Celsius.

"gas-dangerous space" means:

1. a space in the cargo area not arranged or equipped in an approved manner to ensure that its atmosphere is always maintained in a gas-safe condition;
2. an enclosed space outside the cargo area, through which any piping that may contain liquid or gaseous products passes, or within which the piping terminates, unless approved arrangements are installed to prevent any escape of product vapor into the atmosphere of that space;
3. a cargo containment system and cargo piping which is,
   1. (i) a hold space where cargo is carried in a cargo containment system requiring a secondary barrier;
   2. (ii) a hold space where cargo is carried in a cargo containment system not requiring a secondary barrier;
4. a space separated from a hold space described in (c)(i) by a single gas-tight steel boundary;
5. a cargo pump room and cargo compressor room;
6. a zone on the open deck, or semi-enclosed space on the open deck, within 3 metres of any cargo tank outlet, gas or vapor outlet, cargo pipe flange, cargo valve, or entrances and ventilation openings to cargo pump rooms and cargo compressor rooms;
7. the open deck over the cargo area, and 3 metres forward and aft of the cargo area on the open deck, up to a height of 2.4 metres above the weather deck;
8. a zone within 2.4 metres of the outer surface of a cargo containment system where the surface is exposed to the weather;
9. an enclosed or semi-enclosed space containing pipes carrying cargo;
10. a compartment for cargo hoses;
11. an enclosed or semi-enclosed space having a direct opening into any gas-dangerous space or zone.

"hold space" means the vessel space in which a cargo containment system is situated;

"interbarrier space" means that space between a primary and secondary barrier, whether or not completely or partially occupied by insulation or other material;

"primary barrier" means the inner element designed to contain the cargo when the cargo containment system includes two boundaries;

"secondary barrier" means the liquid-resisting outer element of a cargo containment system designed to temporarily contain leakage of liquid cargo through the primary barrier and to prevent cooling of the ship's structure to an unsafe level.

Minimum Requirements

26. (1) All minimum requirements for issuance of the marine chemist's certificate as stated in PART II shall be met prior to commencement of hot work or entry in spaces that have carried, or been exposed to, flammable cryogenic liquids or their vapors.

(2) The special safety designation "Safe for Repair Yard Entry" applies only to flammable cryogenic liquid carriers; it describes vessels with compartments and spaces tested by sampling at remote sampling stations, and the atmospheres proved to be not less than 19.5 percent or more than 23 percent oxygen and less than 10 percent of the lower flammable limit, or with compartments inerted as in subsection 7(5).

(3) Vessels with cargo containment systems that have not met the criteria of subsection 26(2) may undergo specific limited repairs in locations outside the gas-dangerous spaces; these repairs or alterations shall not be undertaken until a marine chemist's certificate is obtained.

(4) When undergoing the repairs in subsection 26(3), the vessel shall be berthed in a special location with due regard to the hazards of the location and to hazards to adjacent property; if the marine chemist questions the safety of any aspect of the site selection, he shall consult the proper governmental authorities.

(5) Interbarrier spaces or insulation may contain pockets of cargo vapors that can be released over varying time periods; the marine chemist shall inspect for gas concentration and combustible materials before work begins in or on the boundaries of these areas.

(6) The marine chemist shall require the following information before making his inspection:

1. description and schematic arrangement of means for inerting cargo tanks, hold spaces, or interbarrier spaces, as applicable;
2. description and instruction manual for calibration of the cargo leak detector equipment;
3. schematic plan showing locations of leak detectors and sampling points;
4. schematic plan(s) of liquid and vapor cargo piping;
5. Canadian Coast Guard Letter of Compliance and Certificate of Fitness for Canadian-flag vessels or the Certificate of Inspection and Certificate of Fitness for Canadian-flag vessels;
6. the recent history of cargoes handled, with special reference to outturn and any pertinent unusual incidents encountered.

Minimum Conditions

27. (1) Minimum conditions to be met before the issuance of a marine chemist's certificate for spaces that have contained, or been exposed to, flammable cryogenic liquids or their vapors shall be as in sections 17 through 20 (insofar as they are applicable) and as specified in this section.

(2) When vessels are undergoing repairs, no venting of cargo tanks, systems, or other spaces that may contain inert gas or flammable vapors shall take place without approval of the marine chemist; any other activity that may similarly alter the atmosphere near the repair work may only be undertaken with such approval.

(3) Vessels able to burn cargo boil-off as fuel for their main propulsion system or for other purposes shall be inspected to assure that gas supply lines to the boiler room or other spaces have been properly secured, inerted, or otherwise properly treated, prior to repairs to this system.

(4) Cargo machinery or systems shall be adequately purged and ventilated to remove cargo vapor or inert gas before opening for repairs.

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