Section 1 General

101.

Application

1. This requirements in this Chapter apply to the ships carrying CNG in bulk intended to be regis- tered and classed with the Society.

2. The requirements not specified in this Section are to be in accordance with the regulations in the

Ch. 1 Sec. 1.

102. Plan and Documents

For a ship requiring classification survey during construction, plans and documents(triplicate for ap- proval and 1 copy for reference), specified below para. 1 and 2, are to be submitted and approved before the work is commenced.

1. Plans and documents for approval

(1) Manufacturing specifications for cargo tanks and insulations(including welding procedures, in- spection and testing procedures for weld and cargo tanks, properties of insulation materials and their processing manual and working standards)

(2) Details of cargo tank construction

(3) Arrangement of cargo tank accessories

(4) Details of cargo tank supports, deck portions through which cargo tanks penetrate, and their sealing devices, if any

(5) Location of void spaces and accesses to dangerous zones

(6) Air locks between safe and dangerous zones

(7) Ventilation duct arrangement in gas-dangerous spaces and adjacent zones

(8) Details of anti-floating and anti-lifting devices and means of protection of hull structure in case of jet leak.

(9) Specifications and standards of materials (including insulations) used for cargo piping system in connection with design pressure and/or temperature

(10) Specifications and standards of materials of cargo tanks, insulations and cargo tank supports

(11) Layout and details of attachment for insulations

(12) Details and installation of the safety valves

(13) Construction details of components of cargo handling systems, including material specification

(14) Constructions of main parts of refrigeration systems

(15) Piping diagrams of cargo and instrument including loading and unloading systems, venting sys- tems and gas-freeing systems, as well as a schematic diagram of the remote controlled valve

system

(16) Piping diagrams of refrigerant for refrigeration systems (if applicable)

(17) Bilge and ballast system in cargo area

(18) Ventilation system in cargo area

(19)

Details and installation of the various monitoring and control systems, including the devices for measuring the level of the cargoes in the tanks (if applicable) and the temper-

atures/pressure in the containment system

(20) Diagram of gas-detection system

(21) Emergency shutdown system

(22) Diagrams of inert gas lines and details of pressure adjusting devices for hold spaces

(23)

(24)

Sectional assembly, details of nozzles, fitting arrangement and details of fittings for various pressure vessels

Details of valves for special purpose, cargo hoses, expansion joints, filters, etc., for cargo pip- ing system

(25) Piping diagram, constructions and particulars of utilization units, where cargo is used as fuel.

(26) Electric wiring plans and a table of electrical equipment in dangerous spaces

(27) Arrangement of earth connections for cargo tanks, pipe lines, machinery, equipment, etc.

(28) Plans showing dangerous spaces

(29) Fire extinguishing system stipulated in Sec 11.

(30) Blow down system, if any

(31) Hull structure heating system, if any

(32) Document for Formal Safety Assessment, if applicable

(33)

The documents stating the alternative means of inspection for cargo tank from inside(if there is no access for inspection of each cargo tank from inside due to the design)

2. Plans and Documents for reference

(1) Principal basic design and technical reports of cargo containment systems

(2) Data of test method and its result, where model test is carried out in compliance with the re- quirements of Sec 4.

(3) Data for notch toughness, corrosiveness, physical and mechanical properties of materials and

welded parts at the minimum design temperature and room temperature, where new materials or welding methods are adopted for constructing the cargo tanks, insulations and others

(4) Data of design loads stipulated in 403.

(5) Calculation sheets of cargo tanks and supports stipulated in 404. to 406.

(6) Data of the test method and the results, where model tests were carried out to demonstrate the strength and performance of cargo tanks, insulations, cargo tank supports

(7) Calculation sheets of heat transfer on the main parts of cargo tank under various condition of

loading, where considered necessary by the Society.

(8) Calculation sheets of the thermal stress on the main parts of cargo tank at the condition of the temperature distribution stipulated in (7), where considered necessary by the Society

(9) Stress analysis of the cargo tanks, including fatigue analysis and crack propagation analysis for cargo tanks.

(10) Calculation of the thermal insulation suitability and refrigeration plant capability, if any, cool- ing down and temperature gradients during loading and unloading operations

(11)

Calculation sheets of temperature distribution on hull structure, where considered necessary by

the Society

(12) Specifications of cargo handling systems

(13)

(14)

Composition and characteristics of natural gas to be carried (including maximum pressure,

minimum and maximum temperature, a saturated vapour pressure diagram within the necessary temperature range, corrosivity and other important design conditions)

Calculation sheets of relieving capacity for pressure relief valves of cargo tank (including cal-

culation of the back pressure in cargo vent system)

(15) Cargo piping arrangement

(16) Calculation sheets of filling limits for cargo tanks

(17)

Arrangement of access manholes stipulated in 305. in cargo tank area and the guide for ac- cess through these manholes.

(18) Operation manual stipulated in Sec 16.

(19) Calculation for ship survival capability stipulated in Sec 2.

103. Safety Goal and Formal Safety Assessment

Where a new concept design other than these guidance for all or partial system is adopted, a quan- tified formal safety assessment complying with the principles in IMO Res. MSC/Circ. 1023 is to be carried and the relevant data are to be submitted in order to document that the safety level is equivalent or better than these guidance. It is the responsibility of the designer and/or the owner to define the applicable risk acceptance criteria.

104.

1.

2.

Other Requirements

Ships carrying CNG in bulk of 20.000 DWT and above are to be provided with emergency towing arrangements complied with the requirements in SOLAS Regulation II-1/3.4.

Ships carrying CNG in bulk of 10.000 GT and above are to be provided with steering gear ar- rangements complied with the requirements in Pt 5, Ch 7, Sec 6 of the Rules.

105. Hazards

Hazards considered in this Guidance are fire, corrosivity, low temperature and pressure.

106. Definitions

The definitions of terms are to be as specified in the following and Sec 4, unless otherwise speci- fied elsewhere.

1. "Accommodation spaces" are those spaces used for public spaces, corridors, lavatories, cabins, offices, hospitals, cinemas, games and hobbies rooms, barber shops, pantries containing no cooking appliances and similar spaces. Public spaces are those portions of the accommodation which are used for halls, dining rooms, lounges and similar permanently enclosed spaces.

2. "A class divisions" are those divisions formed by bulkheads and decks which comply with the following criteria:

(1) they are constructed of steel or other equivalent material;

(2) they are suitably stiffened;

(3) they

are insulated with approved non-combustible materials such that the average temperature of

the unexposed side will not rise more than 140 ℃ above the original temperature, nor will the

temperature, at any one point, including any joint, rise more than 180 ℃ above the original

temperature, within the time listed below: class "A-60" 60 min

class "A-30" 30 min class "A-15" 15 min

class "A-0"

0 min

(4) they are constructed as to be capable of preventing the passage of smoke and flame to the end of the one-hour standard fire test; and

(5) the Society has required a test of a prototype bulkhead or deck in accordance with the Fire

Test Procedures Code to ensure that it meets the requirements above for integrity and temper- ature rise.

3. "Administration" means the Government of the State whose flag the ship is entitled to fly.

4. "Port Administration" means the appropriate authority of the country in the Port of which the ship is loading or unloading.

5. "Blow Down"is depressurizing or disposal of a pressurized cargo inventory from a cargo tank, process vessels, cargo and process piping in a controlled manner via the vent system.

6. "Boiling point" is the temperature at which a product exhibits a vapour pressure equal to the at- mospheric pressure.

7. "Breadth ( )" means the maximum breadth of the ship, measured amidships to the moulded 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. The breadth ( ) is to be measured in meters.

8. "Cargo area" is that part of the ship which contains the cargo containment system, cargo handling system room and turret space, and includes deck areas over the full length and breadth of the part of the ship over the above-mentioned spaces. Where fitted, the cofferdams, ballast or void spaces at the after end of the aftermost hold space or at the forward end of the forwardmost hold space are excluded from the cargo area.

9. "Cargo containment system" is the arrangement for containment of cargo including, where fitted, associated insulation and any intervening spaces, and adjacent structure if necessary for the support of these elements.

10. "Cargo control room" is a space used in the control of cargo handling operations and comply- ing with the requirements of 304.

11. "Cargoes" are compressed natural gas carried by ships subject to this guidance.

12.

"Cargo service spaces" are spaces within the cargo area used for workshops, lockers and store-rooms of more than 2 m in area, used for cargo handling equipment.

13. "Cargo tank" is a tank in accordance with 402. 1.

14. "Cargo piping" is the piping between the cargo tank first stop valve and the cargo loading/un- loading valve.

15. "Cargo loading/unloading valve" is the valve isolating the cargo piping from external piping.

16. "Cargo hold vent pipes" are low pressure piping for venting of cargo hold spaces to vent mast.

17. "Cargo vent piping" is the piping from the cargo relief valve to the vent mast.

18.

"Cofferdam" is the isolating space between two adjacent steel bulkheads or decks. This space may be a void space or a ballast space.

19. "Control stations" are those spaces in which ships" radio or main navigating equipment or the emergency source of power is located or where the fire-recording or fire-control equipment is centralized. This does not include special fire-control equipment which can be most practically located in the cargo area.

20.

"Ships carrying CNG in bulk" is a ship constructed or adapted and used for the carriage in bulk of compressed natural gas.

21. "Design temperature" is the temperature in accordance with 402. 4.

22. "Design pressure" is the pressure in accordance with 402. 2.

23. “Maximium Allowable Operating Pressure(MAOP)” is the pressure in accordance with 402. 3.

24. "Flammability limits" are the conditions plication of an adequately strong external mability in a given test apparatus.

25. "Gas-dangerous space or zone" is:

defining the state of fuel-oxidant mixture at which ap- ignition source is only just capable of producing flam-

(1) a space in the cargo area which is not arranged or equipped in an approved manner to ensure that its atmosphere is at all times maintained in a gas-safe condition;

(2) an enclosed space outside the cargo area through which any piping containing cargo passes, or within which such piping terminates, unless approved arrangements are installed to prevent any

escape of cargo into the atmosphere of that space;

(3) a cargo containment system and cargo piping;

(4) a hold space;

(5) a space separated from a hold space by a single gastight steel boundary;

(6) a cargo handling system room;

(7) a zone on the open deck, or semi-enclosed space on the open deck, within 3 m of any cargo tank outlet, gas outlet, cargo pipe flange or cargo valve or of entrances and ventilation open- ings to cargo handling system room;

(8)

(9)

the open deck over the cargo area and 3 m forward and aft of the cargo area on the open deck with no limit on height;

the outer surface of a cargo containment system with no limit on height where such surface is

exposed to the weather;

(10) an enclosed or semi-enclosed space in which pipes containing cargo are located;

(11) a compartment for cargo hoses; or

(12)

an enclosed or semi-enclosed space having a direct opening into any gas-dangerous space or zone.

26. "Gas-safe space" is a space other than a gas-dangerous space.

27. "Hold space" is the space enclosed by the ship's structure in which a cargo containment system is situated.

28. "Hold space cover" is the enclosure of hold space above main deck protecting cargo tanks and providing controlled environmental conditions within hold space and is gastight.

29.

"Independent" means that a piping or venting system, for example, is in no way connected to another system and there are no provisions available for the potential connection to other systems.

30. "Insulation space" is the space occupied wholly or in part by insulation.

31. "Length ( )" means 96 % of the total length on a waterline at 85 % of the least moulded 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 that waterline, if that be greater. In ships designed with a rake of keel, the wa- terline on which this length is measured should be parallel to the designed waterline. The length ( ) should be measured in meters.

32. "Machinery spaces of category A" are those spaces and trunks to such spaces which contain:

(1) internal combustion machinery used for main propulsion; or

(2)

internal combustion machinery used for purposes other than main propulsion where such ma-

chinery has in the aggregate a total power output of not less than 375 kW ; or

(3) any oil-fired boiler or oil fuel unit.

33. "Machinery spaces" are all machinery spaces of category A and all other spaces containing pro- pelling machinery, boilers, oil fuel units, steam and internal combustion engines, generators and major electrical machinery, oil filling stations, refrigerating, stabilizing, ventilation and air-con- ditioning machinery, and similar spaces; and trunks to such spaces.

34. "MARVS" is the maximum allowable relief valve setting of a cargo tank.

35. "Oil fuel unit" is the equipment used for the preparation of oil fuel for delivery to an oil-fired boiler, or equipment used for the preparation for delivery of heated oil to an internal combustion engine, and includes any oil pressure pumps, filters and heaters dealing with oil at a pressure of more than 0.18 MPa gauge.

36. "Organization" is the International Maritime Organization (IMO).

37. "Permeability" of a space means the ratio of the volume within that space which is assumed to be occupied by water to the total volume of that space.

38. "Process pressure vessel" means a pressure vessel that is used in a cargo heating/cooling sys- tem, cargo processing/cleaning system or other system that processes cargo onboard.

39.

"Recognized standards" are applicable international or national standards acceptable to the Society.

40. "Relative density" is the ratio of the mass of a volume of a product to the mass of an equal volume of fresh water.

41.

"Separate" means that a cargo piping system or cargo vent system, for example, is not con- nected to another cargo piping or cargo vent system. This separation may be achieved by the use of design or operational methods. Operational methods are not to be used within a cargo tank and are to consist of one of the following types:

(1) removing spool pieces or valves and blanking the pipe ends;

(2) arrangement of two spectacle flanges in series with provisions for detecting leak age into the pipe between the two spectacle flanges.

42. "Service spaces" are those spaces used for galleys, pantries containing cooking appliances, lock- ers, mail and specie rooms, store-rooms, workshops other than those forming part of the machi- nery spaces and similar spaces and trunks to such spaces.

43. "SOLAS" means the International Convention for the Safety of Life at Sea, 1974, as amended.

44. "Vapour pressure" is the equilibrium pressure of the saturated vapour above the liquid expressed in MPa absolute at a specified temperature.

45.

"Void space" is an enclosed space in the cargo area external to a cargo containment system, other than a hold space, ballast space, fuel oil tank, cargo handling system room, or any space in normal use by personnel.