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MODULE 2L-Carriage of Liquefied Gases in Bulk

GENERAL

Application

  • The code applies to ships regardless of their size, including those of less than 500 gross tonnages engaged in the carriage of liquefied gases having a vapor pressure exceeding 2.8 bar absolute at a temperature of 37.8°C, and certain other substances as shown in Chapter 19, when carried in bulk.
  • The Code applies to ships the keels of which are laid or which are at a stage at which:

.1 construction identifiable with the ship begins; and

.2 assembly of that ship has commenced comprising at least 50 tonnages or 1% of the estimated mass of all structural material, whichever is less; on or after 1 July 1998. Ships constructed before 1 July 1998 are to comply with resolution MSC.5 (48) adopted on 17 June 1983 subject to amendments by resolution MSC.30(61) adopted on 11 December 1992.

  • A ship, irrespective of the date of construction, which is converted to a gas carrier on or after 1 July 1998 should be treated as a gas carrier constructed on the date on which such conversion commences.
  • When cargo tanks contain products for which the Code requires a type 1G ship, neither flammable liquids having a flashpoint of 60°C (closed cup test) or less nor flammable products listed in 19 should be carried in tanks located within the protective zone described in 2.6.1.2.
  • Similarly, when cargo tanks contain products for which the Code requires a type 2G/2PG ship, the above-mentioned flammable liquids should not be carried in tanks located within the protective zones described in 2.6.1.2.
  • In each case, the restriction applies to the protective zones within the longitudinal extent of the hold spaces for the cargo tanks loaded with products for which the Code required a type 1G or 2G/2PG ship.
  • The above-mentioned flammable liquids and products may be carried within these protective zones when the quantity retained in the cargo tanks of products for which the Code requires a type 1G or 2G/2PG ship is solely used for cooling, circulation, or fuelling purposes.

Hazards
Hazards of gases covered by this Chapter include fire, toxicity, corrosively, reactivity, low temperature, and pressure.

Definitions

  • 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.
  •  “Anniversary date” means the day and the month of each year which will correspond to the date of expiry of the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk.”
  •  “Boiling point” is the temperature at which a product exhibits a vapor pressure equal to the atmospheric pressure.
  • “Breadth (B)” means the maximum breadth of the ship, 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. The breadth (B) should be measured in meters.
  • Cargo area” is that part of the ship which contains the cargo containment system and cargo pump and compressor rooms and includes deck areas over the full beam and length of the ship above the foregoing Where fitted, the cofferdams, ballast or void spaces at the after the end of the aftermost hold space or the forward end of the forwardmost hold space are excluded from the cargo area.
  • Cargo containment system” is the arrangement for containment of cargo including, where fitted, a primary and secondary barrier, associated insulation and any intervening spaces, and adjacent structure if necessary 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.
  • Cargo service spaces” are spaces within the cargo area used for workshops, lockers, and storerooms of more than 2 m² in area, used for cargo handling equipment.
  • Cargo tank” is the liquid-tight shell designed to be the primary container of the cargo and includes all such containers whether or not associated with insulation or secondary barriers or both.
  • Cofferdam” is the isolating space between two adjacent steel bulkheads or decks. This space may be a void space or a ballast space.
  • 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.
  • Flammability limits” are the conditions defining the state of the fuel-oxidant mixture at which application of an adequately strong external ignition source is only just capable of producing flammability in a given test apparatus.
  • Gas carrier” is a cargo ship constructed or adapted and used for the carriage in bulk of any liquefied gas or other products listed in the table of Chapter 19
  • Gas-dangerous space or zone” is :

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

2 an enclosed space outside the cargo area through which any piping containing liquid or gaseous products passes, or within which such 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 ;

.4.1 a holding space where cargo is carried in a cargo containment system requiring a secondary barrier ;

.4.2 a holding space where cargo is carried in a cargo containment system not requiring a secondary barrier ;

.5 a space separated from a holding space described in 4.1 above by a Gas-tight steel boundary;

.6 a cargo pump room and cargo compressor 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 or vapor outlet, cargo pipe flange or cargo valve, or of entrances and ventilation openings to cargo pump rooms and cargo compressor rooms ;

.8 the open deck over the cargo area and 3 m forward and aft of the cargo area on the open deck up to a height of 2.4 m above the weather deck ;

.9 a zone within 2.4 m of the outer surface of a cargo containment system where the such surface is exposed to the weather ;

.10 an enclosed or semi-enclosed space in which pipes containing products are located. A space that contains gas detection equipment complying with 13.6.5 and space utilizing boil-off gas as fuel and complying with Chapter 16 are not considered gas-dangerous spaces in this context ;

.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.

  • Hold space” is the space enclosed by the ship’s structure in which a cargo containment system is situated.
  • 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 another system.
  • Insulation space” is the space, which may or may not be an intercarrier space, occupied wholly or in part by insulation.
  • “Interbarrier space” is the space between a primary and a secondary barrier, whether or non completely or partially occupied by insulation or other material.
  • Length (L)” means 96% of the total length on a waterline at 85% 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 that waterline, if that be greater. In ships designed with a rake of the keel, the waterline on which this length is measured should be parallel to the designed waterline. The length (L) should be measured in meters.
  • 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 machinery has in the aggregate total power output of not less than 375Kw; or

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

  • Machinery spaces” are all machinery spaces of category A and all other spaces containing propelling machinery, boilers, oil fuel units, steam, and internal combustion engines, generators and major electrical machinery, oil filling stations, refrigerating, stabilizing, ventilation, and air-conditioning machinery, and similar spaces; and trunks to such spaces.
  • MARVS” is the maximum allowable relief valve setting of a cargo tank.
  • 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 1.8 bar.
  • Permeability” of 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.
  • Primary barrier” is the inner element designed to contain the cargo when the cargo containment system includes two boundaries.
  • Secondary barrier” is the liquid-resisting outer element of a cargo containment system designed to afford temporary containment of any envisaged leakage of liquid cargo through the primary barrier and to prevent the lowering of the temperature of the ship’s structure to an unsafe level. Types of secondary barriers are more fully defined in Chapter 4.
  • Recognized standards” are applicable international or national standards acceptable to the Administration or standards laid down and maintained by an organization that complies with the standards adopted by the Organization* and which is recognized by the Administration. * refer to the Minimum standards for Recognized Organizations Acting on Behalf of the Administration, set out in Appendix 1 to the Guidelines for the Authorization of Organizations Acting on Behalf of the Administration, adopted by the Organization by resolution A.739(18).
  • Relative density” is the ratio of the mass of a volume of a product to the mass of an equal volume of fresh water.
  • Separate” means that a cargo piping system or cargo vent system, for example, is not connected to another cargo piping or cargo vent system. This separation may be achieved by the use of design or operational methods. Operational methods should not be used within a cargo tank and should 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 leakage into the pipe between the two spectacle flanges.

  • Service spaces” are those spaces used for galleys, pantries containing cooking appliances, lockers, mail and specie rooms, store-rooms, workshops other than those forming part of the machinery spaces, and similar spaces and trunks to such spaces.
  • Tank cover” is the protective structure intended to protect the cargo containment system against damage where it protrudes through the weather deck or to ensure the continuity and integrity of the deck structure.
  • “Tank dome” is the upward extension of a portion of a cargo tank. In the case of below-deck cargo containment systems, the tank dome protrudes through the weather deck or through a tank cover.
  • Toxic products” are those identified by a “T” in column “f” in the table of Chapter 19
  • Vapour pressure” is the equilibrium pressure of the saturated vapor above the liquid expressed in bar absolute at a specified temperature.
  • Void space” is an enclosed space in the cargo area external to a cargo containment system, other than a holding space, ballast space, fuel oil tank, cargo pump or compressor room, or any space in normal use by personnel.

Survey requirements

  •  The structure, equipment, fittings, arrangements, and material(other than items in respect of which a Cargo ship Safety Construction Certificate, Cargo Ship Safety Equipment Certificate, and Cargo Ship Radiotelegraphy Certificate or Radiotelephony Certificate are issued) of a gas carrier should be subjected to the following surveys:

.1 An initial survey before the ship is put in service or before the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk is issued for the first time, which should include a complete examination of its structure, equipment, fittings, arrangements, and material in so far as the ship is covered by the Code. This survey should be such to ensure that the structure, equipment, fittings, arrangements, and material fully complies with the applicable provisions of the Code.

.2 A renewal survey at intervals specified by the Administration, but not exceeding five years, except where regulation 1.5.6.2.2, 1.5.6.5, 1.5.6.6, or 1.5.6.7 is applicable. The renewal survey should be such to ensure that the structure, equipment, fitting, arrangements, and material comply with the applicable provisions of the Code.

.3 An intermediate survey within 3 months before or after the second-anniversary date or within 3 months before or after the third-anniversary date of the Certificate which should take the place of one of the annual surveys specified in 1.5.2.1.4. The intermediate survey should be such to ensure that the safety equipment, other equipment, and associated pump and piping systems fully comply order. Such intermediate surveys should be endorsed on the Certificate issued under 1.5.4. or 1.5.5;

.4 An annual survey within three months before or after the anniversary date of the Certificate, including a general inspection of the structure, equipment, fittings, arrangements, and material referred to to

  •  to ensure that they have been maintained in accordance with which what the ship is intended. Such annual surveys should be endorsed on the Certificate issued under 1.5.4 or 1.5.5;

.5 An additional survey, either general or partial according to the circumstances, should be made when required after an investigation prescribed in 1.5.3.3, or whenever any important repairs or renewals are made. Such a survey should ensure that the necessary repairs or renewals have been effectively made, that the material and workmanship of such repairs or renewals are satisfactory; and that the ship is fit to
proceed to sea without danger to the ship or persons on board or without presenting an unreasonable threat of harm to the marine environment.

  • Maintenance of conditions after survey
  • The condition of the ship and its equipment should be maintained to conform with the provisions of the Code to ensure that the ship will remain fit to proceed to sea without danger to the ship or persons on board or without presenting unreasonable threats of harm to the marine environment.
  • After any survey of the ship under 1.5.2has been completed, no change should be made in the structure, equipment, fittings, arrangements, and the material covered by the survey, without the sanction of the Administration, except by direct replacement.
  • Whenever an accident occurs to a ship or a defect is discovered, either, which affects the safety of the ship or the efficiency or completeness of its life-saving appliances or other equipment, the master or owner of the ship should report at the earliest opportunity to the Administration, the nominated surveyor or recognized organization responsible for issuing the relevant certificate, who should cause investigations to be initiated to determine whether a survey, as required by 1.5.2.1.5, is necessary. If the ship is in a port of another Contracting Government, the master or owner should also report immediately to the Port Administration concerned and the nominated surveyor or recognized organization should ascertain that such a report has been made.
  • Issue and endorsement of International Certificate of Fitness
  • A certificate called an International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk, should be issued after an initial or renewal survey to a gas carrier engaged in international voyages which complies with the relevant provisions of the Code.
  • An International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk should be drawn up in the form corresponding to the model given in the Appendix. If the language used is neither English nor French, the text should include a translation into one of these languages.
  • The certificate issued under the provisions of this section should be available on board for inspection at all times.
  • Duration and validity of International Certificate of Fitness

Segregation of the cargo area

  • Hold spaces should be segregated from machinery and boiler spaces, accommodation spaces, service spaces and control stations, chain lockers, drinking, and domestic water tanks, and from stores. Hold spaces should be located forward of machinery spaces of category A, other than those deemed necessary by the Society for the safety or navigation of the ship.
  • Where cargo is carried in a cargo containment system not requiring a secondary barrier, segregation of hold spaces from spaces referred to in 2.1.1 or spaces either below or outboard of the hold spaces may be affected by cofferdams, fuel oil tanks, or a single gastight bulkhead of all-welded construction forming an A-60 class division. A gastight A-0 class division is satisfactory if there is no source of ignition or fire
    hazard in the adjoining spaces.
  • Where cargo is carried in a cargo containment system requiring a secondary barrier, segregation of hold spaces from spaces referred to in 2.1.1 or spaces either below or outboard of the hold spaces which contain a source of ignition or fire hazard should be affected by cofferdams or fuel oil tanks. If there is no source of ignition or fire hazard in the adjoining space, segregation may be by a single A-0 class division which is gastight.
  • When cargo is carried in a cargo containment system requiring a secondary barrier :
    .1 at temperatures below -10°C hold spaces should be segregated from the sea by a double bottom; and
    .2 at temperatures below -55°C, the ship should also have a longitudinal bulkhead forming side tanks.
  • Any piping system which may contain cargo or cargo vapor should :

.1 be segregated from other piping systems, except where inter-connections are required for cargo-related operations such as purging, gas-freeing, or inerting. In such cases, precautions should be taken to ensure that cargo or cargo vapor cannot enter such other piping systems through the inter-connections ;

.2 except as provided in Chapter 16, not pass through any accommodation space, service space, or control station or through a machinery space other than a cargo pump room or cargo compressor space ;

.3 be connected into the cargo containment system directly from the open deck except that pipes installed in a vertical trunk-way or equivalent may be used to traverse void spaces above a cargo containment system and except that pipes for drainage, venting, or purging may traverse cofferdams ;

.4 except for bow or stern loading and unloading arrangements in accordance with 3.8 and emergency cargo jettisoning piping systems in accordance with 3.8 and except in accordance with Chapter 16, be located in the cargo area above the open deck; and

.5 except for athwartship shore connection piping is not subject to internal pressure at sea or emergency cargo jettisoning piping systems, be located inboard of the transverse tank location requirements of 2.6.1.

  • Emergency cargo jettisoning arrangements may be led aft externally to accommodation spaces, service spaces or control stations, or machinery spaces, but should not pass through them. If an emergency cargo jettisoning arrangement is permanently installed a suitable means of isolation from the cargo piping should be provided within the cargo area.
  • Arrangements should be made for sealing the weather decks in way of openings for cargo containment systems.

Accommodation, service and machinery spaces, and control stations

  •  No accommodation space, service space, or control station should be located within the cargo area.
    The bulkhead of accommodation spaces, service spaces, or control stations that face the cargo area should be so located as to avoid the entry of gas from the hold space to such spaces through a single failure of a deck or bulkhead on a ship having a containment system requiring a secondary barrier.
  • In order to guard against the danger of hazardous vapors, due consideration should be given to the location of air intakes and openings into accommodation, service, and machinery spaces and control stations in relation to cargo piping, cargo vent systems, and machinery space exhaust from gas burning arrangements.
  • Access through doors, gastight or otherwise, should not be permitted from a gas-safe space to a gas dangerous space, except for access to service spaces forward of the cargo area through air-locks as permitted by 3.6.1 when accommodation spaces are aft.
  • Entrances, air inlets, and openings to accommodation spaces, service spaces, machinery spaces, and control stations should not face the cargo area. They should be located on the end bulkhead not facing the cargo area or on the outboard side of the superstructure or deckhouse or on both at a distance of at least 4% of the length (L) of the ship but not less than 3 m from the end of the superstructure or deckhouse facing the cargo area. This distance, however, need not exceed 5 m. Portlights facing the cargo area and on the side of the superstructures of deckhouses within the distance mentioned above should be of the fixed (non-opening) type. Wheelhouse windows may be non-fixed and navigating bridge doors may be located within the above limits so long as they are so designed that a rapid and efficient gas and vapor tightening of the wheelhouse can be ensured. For ships dedicated to the carriage of cargoes that have neither flammable nor toxic hazards, the Administration may approve relaxations from the above requirements.
  • Side scuttles in the shell below the uppermost continuous deck and in the first tier of the superstructure or deckhouse should be of the fixed (non-opening) type.
  • All air intakes and openings into the accommodation spaces, service spaces, and control stations should be fitted with closing devices. For toxic gases, they should be operated from inside the space.

Cargo pump rooms and cargo compressor rooms

  • Cargo pump rooms and cargo compressor rooms should be situated above the weather deck and located within the cargo area unless specially approved by the Society. Cargo compressor rooms should be treated as cargo pump rooms for the purpose of fire protection according to SOLAS regulation II-2/9.2.4. (replaced by Res.MSC.220(82) )
  •  When cargo pump rooms and cargo compressor rooms are permitted to be fitted above or below the weather deck after the end of the aftermost hold space or at the forward end of the forwardmost hold space, the limits of the cargo area as defined in 1.3.6 should be extended to include the cargo pump rooms and cargo compressor rooms for the full breadth and depth of the ship and deck areas above those spaces.
  • Where the limits of the cargo area are extended by this paragraph, the bulkhead which separates the cargo pump rooms and cargo compressor rooms from accommodation and service spaces, control stations and machinery spaces of category A should be so located as to avoid the entry of gas into these spaces through a single failure of a deck or bulkhead.
  • Where pumps and compressors are driven by shafting passing through a bulkhead or deck, gastight seals with efficient lubrication or other means of ensuring the permanence of the gas seal should be fitted in way of the bulkhead or deck.
  • Arrangements of cargo pump rooms and cargo compressor rooms should be such to ensure safe unrestricted access for personnel wearing protective clothing and breathing apparatus, and in the event of injury to allow unconscious personnel to be removed. All valves necessary for cargo handling should be readily accessible to personnel wearing protective clothing. Suitable arrangements should be made to deal with drainage of pump and compressor rooms.

Cargo control rooms

  • Any cargo control room should be above the weather deck and may be located in the cargo area.
    The cargo control room may be located within the accommodation spaces, service spaces, or control stations provided the following conditions are complied with :

.1 the cargo control room is a gas-safe space; and
.2.1 if the entrance complies with 3.2.4, the control room may have access to the spaces described above ;
.2.2 if the entrance does into comply with 3.2.4, the control room should have no access to the spaces described above and the boundaries to such spaces should be insulated to A-60 class integrity

  • If the cargo control room is designed to be a gas-safe space, instrumentation should, as far as possible, be by indirect reading systems and should in any case be designed to prevent any escape of gas into the atmosphere of that space. The location of the gas detector within the cargo control room will not violate the gas-safe space if installed in accordance with 13.6.5.
  • If the cargo control room for ships carrying flammable cargoes is a gas-dangerous space, sources of ignition should be excluded. Consideration should be paid to the safety characteristics of any electrical installations.

Access to spaces in the cargo area

  • Visual inspection should be possible of at least one side of the inner hull structure without the removal of any fixed structure or fitting. If such a visual inspection, whether combined with those inspections required in 3.5.2, 4.7.7, or 4.10.16 or not, is only possible at the outer face of the inner hull, the inner hull should not be a fuel-oil tank boundary wall.
  • Inspection of one side of any insulation in hold spaces should be possible. If the integrity of the insulation system can be verified by inspection of the outside of the hold space boundary when tanks are at service temperature, an inspection of one side of the insulation in the hold space need not be required.
  • Arrangements for hold spaces, void spaces, and other spaces that could be considered gas-dangerous and cargo tanks should be such as to allow entry and inspection of any such space by personnel wearing protective clothing and breathing apparatus and in the event of injury to allow unconscious personnel to be removed from the space and should comply with the following :
    .1 Access should be provided :
    .1.1 to cargo tanks direct from the open deck ;
    .1.2 through horizontal openings, hatches, or manholes, the dimensions of which should be sufficient to allow a person wearing a breathing apparatus to ascend or descend any ladder without obstruction and also to provide a clear opening to facilitate the hoisting of an injured person from the bottom of the space; the minimum clear opening should be not less than 600 mm by 600 mm; and
    .1.3 through vertical openings, or manholes providing passage through the length and breadth of the space, the minimum clear opening of which should be not less than 600 mm by 800 mm at a height of not more than 600 mm from the bottom plating unless gratings or other footholds are provided.
  • Access from the open weather deck to gas-safe spaces should be located in a gas-safe zone at least 2.4 m above the weather deck unless the access is by means of an air-lock in accordance with 3.6.

 Air locks

  •  An air-lock should only be permitted between a gas-dangerous zone on the open weather deck and a gas-safe space and should consist of two steel doors substantially gastight spaced at least 1.5 m but not more than 2.5 m apart.
  • The doors should be self-closing and without any holding-back arrangements.
  • An audible and visual alarm system to give a warning on both sides of the airlock should be provided to indicate if more than one door is moved from the closed position.
  • In ships carrying flammable products, electrical equipment which is not of the certified safe type in spaces protected by airlocks should be de-energized upon loss of overpressure in the space (see also 10.1.4). Electrical equipment which is not of the certified safe type for maneuvering, anchoring, and mooring equipment as well as the emergency fire pumps should not be located in spaces to be protected
    by air-locks.
  • The airlock space should be mechanically ventilated from a gas-safe space and maintained at an over-pressure to the gas-dangerous zone on the open weather deck.
  • The air-lock space should be monitored for cargo vapor.
  • Subject to the requirements of the International Convention on Load Lines in force, the door still should not be less than 300 mm in height.

Bilge, ballast, and fuel oil arrangements
(Paragraph 3.7.2.2 A applies to ships constructed on or after 1 July 2002)

  • Where cargo is carried in a cargo containment system not requiring a secondary barrier, hold spaces should be provided with suitable drainage arrangements not connected with the machinery space. Means of such leakage should be provided
  • Where there is a secondary barrier, suitable drainage arrangements for dealing with any leakage into the hold or insulation spaces through adjacent ship structures should be provided. The suction should not be led to pumps inside the machinery space. Means of detecting such leakage should be provided.
  • The hold or intercarrier spaces of Type A independent tank ships should be provided with a drainage system suitable for handling liquid cargo in the event of cargo tank leakage or rupture. Such arrangements should provide for the return of any cargo leakage to the liquid cargo piping.
  • Arrangements referred to in 3.7.2.1 should be provided with a removable spool piece.
  • In the case of internal insulation tanks, means of detecting leakage and drainage arrangements are not required for inter-barrier spaces and spaces between the secondary barrier and the inner hull or independent tank structure which are completely filled by insulation material complying with 4.9.7.2.
  • Ballast spaces, including wet duct keels used as ballast piping, fuel-oil tanks, and gas-safe spaces may be connected to pumps in the machinery spaces. Dry duct keels with ballast piping passing through may be connected to pumps in the machinery spaces, provided the connections are led directly to the pumps and the discharge from the pumps lead directly overboard with no valves or manifolds in either line which could connect the line from the duct keel to lines serving gas-safe spaces. Pump vents should not be open to machinery spaces.

Bow or stern loading and unloading arrangements

  • Subject to the requirements of this section, cargo piping may be arranged to permit bow or stern loading and unloading.
  • Bow or stern loading and unloading lines that are led past accommodation spaces, service spaces, or control stations should not be used for the transfer of products requiring a type 1G ship. Bow or stern loading and unloading lines should not be used for the transfer of toxic products as specified in 1.3.38unless specifically approved by the Administration.
  • Portable arrangements should not be permitted.
  • In addition to the requirements of Chapter 5 the following provisions apply to cargo piping and related piping equipment :

.1 Cargo piping and related piping equipment outside the cargo area should have only welded connections. The piping outside the cargo area should run on the open deck and should be at least 76 mm inboard except for the thwart ship’s shore connection piping. Such piping should be clearly identified and fitted with a shutoff valve at its connection to the cargo piping system within the cargo area. At this location, it should also be capable of being separated by means of a removable spool piece and blank flanges when not in use.

.2 The piping is to be full penetration butt welded and fully radiographed regardless of pipe diameter and design temperature. Flange connections in the piping are only permitted within the cargo area and at the shore connection.

.3 Arrangements should be made to allow such piping to be purged and gas-freed after use When not in use, the spool pieces should be removed and the pipe ends be blank-flanged. The vent pipes connected with the purge should be located in the cargo area.

  •  Entrances, air inlets, and openings to accommodation spaces, service spaces, machinery spaces, and control stations should not face the cargo shore connection location of bow or stern loading and unloading arrangements. They should be located on the outboard side of the superstructure or deckhouse at a distance of at least 4% of the length of the ship but not less than 3 m from the end of the superstructure or deckhouse facing the cargo shore connection location of the bow or stern loading and unloading arrangements. This distance, however, need not exceed 5 m. Side scuttles facing the shore connection location and on the sides of the superstructure or deckhouse within the distance mentioned above should be of the fixed (non-opening) type. In addition. during the use of the bow or stern loading and unloading
    arrangements, all doors, ports, and other openings on the corresponding superstructure or deckhouse side should be kept closed. Where, in the case of small ships, compliance with 3.2.4 and this paragraph is not possible, the Society may approve relaxations from the above requirements.
  • Deck openings and air inlets to spaces within distances of 10 m from the cargo shore connection location should be kept closed during the use of bow or stern loading or unloading arrangements.
  • Electrical equipment within a zone of 3 m from the cargo shore connection location should be in accordance with Chapter 10.

CARGO CONTAINMENT

Definitions

  • Integral tanks
  1. Integral tanks form a structural part of the ship’s hull and are influenced in the same manner and by the same loads which stress the adjacent hull structure.
  2. The design vapor pressure as defined in 4.2.6 should not normally exceed 0.25 bar. If, however, the hull scantlings are increased accordingly, may be increased to a higher value but less than 0.7 bar.
  3. Integral tanks may be used for products provided the boiling point of the cargo is not below – 10°C. A lower temperature may be accepted by Society subject to special consideration.
  • Membrane tanks
  1. Membrane tanks are non-self-supporting tanks that consist of a thin layer (membrane) supported through insulation by the adjacent hull structure. The membrane is designed in such a way that thermal and other expansion or contraction is compensated for without undue stressing of the membrane.
  2. The design vapor pressure should not normally exceed 0.25 bar. If, however, the hull scantlings are increased accordingly and consideration is given, where appropriate, to the strength of the supporting insulation, may be increased to a higher value but less than 0.7 bar.
  3. The definition of membrane tanks does not exclude designs such as those in which nonmetallic membranes are used or in which membranes are included or incorporated in insulation. Such designs require, however, special consideration by Society. In any case, the thickness of the membranes should normally not exceed 10 mm.
  • Semi-membrane tanks
  1. Semi-membrane tanks are non-self-supporting tanks in the loaded condition and consist of a layer, parts of which are supported through insulation by the adjacent hull structure, whereas the rounded parts of this layer connecting the above-mentioned supported parts are designed also to accommodate the thermal and other expansion or contraction
  2. The design vapor pressure should not normally exceed 0.25 bar. If, however, the hull scantlings are increased accordingly, and consideration is given, where appropriate, to the strength of the supporting insulation, may be increased to a higher value but less than 0.7 bar.
  • Independent tanks
  1. Independent tanks are self-supporting; they do not form part of the ship’s hull and are not essential to the hull strength. There are three categories of independent tanks referred to in 4.2.4.2 – 4.2.4.4
  2. Type A independent tanks are tanks that are designed primarily using recognized standards of classical ship-structural analysis procedures. Where such tanks are primarily constructed of plane surfaces (gravity tanks), the design vapor pressure should be less than 0.7 bar.
  3. Type B independent tanks are tanks that are designed using model tests, refined analytical tools, and analysis methods to determine stress levels, fatigue life, and crack propagation characteristics. Where such tanks are primarily constructed of plane surfaces (gravity tanks) the design vapor pressure should be less than 0.7 bar.
  • Internal insulation tanks
  1. Internal insulation tanks are non-self-supporting and consist of thermal insulation materials which contribute to the cargo containment and are supported by the structure of the adjacent inner hull or of an independent tank. The inner surface of the insulation is exposed to the cargo.
  2. The two categories of internal insulation tanks are :

Type 1 tanks are tanks in which the insulation or a combination of the insulation and one or more liners functions only as the primary barrier. The inner hull or an independent tank structure should function as the secondary barrier when required.

Type 2 tanks are tanks in which the insulation or a combination of the insulation and one or more liners functions as both the primary and the secondary barrier and where these barriers are clearly distinguishable.

The term “liner” means a thin, non-self-supporting, metallic, nonmetallic, or composite material that forms part of an internal insulation tank in order to enhance its fracture resistance or other mechanical properties. A liner differs from a membrane in that it is not intended to function alone as a liquid barrier.

  • Internal insulation tanks should be of suitable materials enabling the cargo containment system to
    be designed using model tests and refined analytical methods as required in 4.4.7
  • The design vapor pressure should not normally exceed 0.25 bar. If, however, the cargo containment system is designed for higher vapor pressure, may be increased to such a higher value, but not exceed 0.7 bar if the internal insulation tanks are supported by the inner hull structure. However, a design vapor pressure of more than 0.7 bar may be accepted by Society provided the internal
    insulation tanks are supported by suitable independent tank structures.
  • Design vapor pressure
  1. The design vapor pressure is the maximum gauge pressure at the top of the tank which has been used in the design of the tank.
  2. For cargo tanks where there is no temperature control and where the pressure of the cargo is dictated only by the ambient temperature, P 0 should not be less than the gauge vapor pressure of the cargo at a temperature of 45°C. However, lesser values of this temperature may be accepted by the Society for ships operating in restricted areas or on voyages of restricted duration and account may be taken in such cases of any insulation of the tanks. Conversely, higher values of this temperature may be required for ships permanently operating in areas of high ambient temperature.

General

  • Tanks together with their supports and other fixtures should be designed taking into account proper combinations of the following loads:

internal pressure, external pressure

dynamic loads due to the motions of the ship

thermal loads

sloshing loads

loads corresponding to ship deflection

tank and cargo weight with the corresponding reactions in way of supports

insulation weight

loads in way of towers and other attachment

The extent to which these loads should be considered depends on the type of tank and is more fully detailed in the following paragraphs.

  • The tanks should be designed for the most unfavorable static heel angle within the range of 0° to 30° without exceeding allowable stresses given in 4.5.1.
  • Internal pressure
  • The internal pressure in bars gauge resulting from the design vapor pressure and the internal liquid pressure defined in 4.3.2.2 but not including effects of liquid sloshing, should be calculated as follows: = + (bar)

Allowable stresses and corrosion allowances

  • Allowable stresses
  • For integral tanks, allowable stresses should normally be those given for hull structure in recognized standards.
  • For type, A independent tanks primarily constructed of plane surfaces, the stresses for primary and secondary members (stiffeners, web frames, stringers, girders) when calculated by classical analysis procedures should not exceed the lower of /2.66 or /1.33 for carbon-manganese steels and aluminum alloys.
  • For type B independent tanks, primarily constructed of bodies of revolution, the allowable stresses should not exceed :
    ≤ f
    ≤ 1.5f
    ≤ 1.5F
    + ≤ 1.5F
    + ≤ 1.5F
    where :
    = equivalent primary general membrane stress

= equivalent primary local membrane stress
= equivalent primary bending stress
f = the lesser of or
F = the lesser of or
The values of A, B, C, and D should be shown on the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk and should have at least the minimum values:

  • For type B independent tanks, primarily constructed of plane surfaces, the Society may require compliance with additional or other stress criteria.
  • For type C independent tanks the maximum allowable membrane stress to be used in calculation should be the lower of :
    or
    where :
    and are as defined in 4.5.1.7

The values of A and B should be shown on the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk,

.1 = specified minimum yield stress at room temperature (N/mm²). If the stress-strain curve does not show defined yield stress, the 0.2% proof stress applies.

= specified minimum tensile strength at room temperature (N/mm²).

For welded connections in aluminum alloys, the respective values of or in annealed conditions should be used.

.2 The above properties should correspond to the minimum specified mechanical properties of the material, including the weld metal in the as-fabricated condition. Subject to special consideration by the Society, the account may be taken of enhanced yield stress and tensile strength at low temperatures. The temperature on which the material properties are based should be shown on the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk provided for in 1.5.

  • The equivalent stress (von Mises, Huber) should be determined by:

where :
= total normal stress in x-direction
= total normal stress in the y-direction
= total shear stress in the x-y plane.

Corrosion allowances

  • No corrosion allowance should generally be required in addition to the thickness resulting from the structural analysis. However, where there is no environmental control around the cargo tank, such as inerting, or where the cargo is of a corrosive nature, Society may require a suitable corrosion allowance.
  • For pressure vessels, no corrosion allowance is generally required if the contents of the pressure vessel are non-corrosive and the external surface is protected by an inert atmosphere or by appropriate insulation with an approved vapor barrier. Paint or other thin coatings should not be credited as protection. Where special alloys are used with acceptable corrosion resistance, no corrosion allowance should be required. If the above conditions are not satisfied, the scantlings calculated according to 4.4.6 should be increased as appropriate.

Secondary barrier

  • Where the cargo temperature at atmospheric pressure is below -10°C, a secondary barrier should be provided when required by 4.7.3 to act as a temporary containment for any envisaged leakage of liquid cargo through the primary barrier.
  • Where the cargo temperature at atmospheric pressure is not below -55°C, the hull structure may act as a secondary barrier. In such a case

.1 the hull material should be suitable for the cargo temperature at atmospheric pressure and
.2 the design should be such that this temperature will not result in unacceptable hull stresses.

  • Secondary barriers in relation to tank types should normally be provided in accordance with the following Table. e.

Insulation

  • Where a product is carried at a temperature below -10 °C suitable insulation should be provided to ensure that the temperature of the hull structure does not fall below the minimum allowable design temperature given in Chapter 6 for the grade of steel concerned, when the cargo tanks are at their design temperature and the ambient temperatures are 5 °C for air and 0 °Cfor seawater. These conditions may generally be used for worldwide service. However, higher values of the ambient temperatures may be accepted by the Society for ships operated in restricted areas. Conversely, lesser values of the ambient temperatures may be fixed by the Society for ships trading occasionally or regularly to areas in latitudes where such lower temperatures are expected during the winter months. The ambient temperatures used in the design should be shown on the International Certificate of Fitness for the Carriage of Liquefied Gases on Bulk
  • Where a complete or partial secondary barrier is required, calculations should be made with the assumptions in 4.8.1 to check that the temperature of the hull structure does not fall below the minimum allowable design temperature given in Chapter 6 for the grade of steel concerned, as detailed in 4.9. The complete or partial secondary barrier should be assumed to be at the cargo temperature at atmospheric
    pressure.

Materials

  • The shell and deck plating of the ship and all stiffeners attached thereto should be in accordance with Recognized Standards unless the calculated temperature of the material in the design condition is below -5°C due to the effect of the low-temperature cargo, in which case the material should be in accordance with table 6.5 assuming the ambient sea and air temperature of 0°C and 5°C respectively. In
    the design condition, the complete or partial secondary barrier should be assumed to be at the cargo temperature at atmospheric pressure, and for tanks without secondary barriers, the primary barrier should be assumed to be at the cargo temperature.
  • Hull material forming the secondary barrier should be in accordance with table 6.2. Metallic materials used in secondary barriers not forming part of the hull structure s4.9.3 Materials used in the construction of cargo tanks should be in accordance with tables 6.1, 6.2, or 6.3.
  • The insulation materials should be suitable for loads that may be imposed on them by the adjacent structure.
  • Where applicable, due to location or environmental conditions, insulation materials should have suitable properties of resistance to fire and flame spread and should be adequately protected against penetration of water vapor and mechanical damage.
  • In ships fitted with membrane or semi-membrane tanks, cofferdams, and all spaces which may normally contain liquid and are adjacent to the hull structure supporting the membrane should be hydrostatically or hydropneumatically tested in accordance with Recognized Standards. In addition, any other hold structure supporting the membrane should be tested for tightness. Pipe tunnels and other
    compartments that do not normally contain liquid need not be hydrostatically tested.
  • In ships fitted with internal insulation tanks where the inner hull is the supporting structure, all inner hull structures should be hydrostatically or hydropneumatically tested in accordance with Recognized Standards, taking into account the MARVS.
  • In ships fitted with internal insulation tanks where independent tanks are the supporting structure,
    the independent tanks should be tested For internal insulation tanks where the inner hull structure or an independent tank structure acts as a secondary barrier, a tightness test of those structures should be carried out using techniques to the satisfaction of the Administration.
  • For type C independent tanks, inspection, and nondestructive testing should be as follows:

.1 Manufacture and workmanship – The tolerances relating to manufacture and workmanship such as out-of-roundness, local deviations from the true form, welded joints alignment, and tapering of plates having different thicknesses, should comply with standards acceptable to the Administration.

.2 Non-destructive testing – As far as completion and extension of non-destructive testing of welded joints are concerned, the extent of non-destructive testing should be total or partial according to standards acceptable to the Administration, but the controls to be carried out should not be less than the following:

.2.1 Total non-destructive testing referred to in 4.4.6.1.3:
Radiography :
butt welds 100% and
Surface crack detection :
all welds 10% ;
reinforcement rings around holes, nozzles, etc. 100%.

As an alternative, ultrasonic testing may be accepted as a partial substitute for radiographic testing, if specially allowed by the Administration. In addition, the Administration may require total ultrasonic testing on welding of reinforcement rings around holes, nozzles, etc.

.2.2 Partial non-destructive testing referred to in 4.4.6.1.3:
Radiography:
butt welds: all-welded crossing joints and at least 10% of the full length at selected positions uniformly distributed and
Surface crack detection :
reinforcement rings around holes, nozzles, etc. 100%
Ultrasonic testing :
as may be required by the Administration in each instance.

  • Each independent tank should be subjected to a hydrostatic or hydropneumatic test as follows :

.1 For type A independent tanks, this test should be so performed that the stresses approximate, as far as practicable, to the design stresses and that the pressure at the top of the tank corresponds at least to the MARVS. When a hydropneumatic test is performed, the conditions should simulate, as far as practicable, the actual loading of the tank and of its supports.

.2 For type B independent tanks, the test should be performed as required in 4.10.10.1 for type A independent tanks. In addition, the maximum primary membrane stress or maximum bending stress in primary members under test conditions should not exceed 90% of the yield strength of the material (as fabricated) at the test temperature. To ensure that this condition is satisfied, when calculations indicate that this stress exceeds 75% of the yield strength, the prototype test should be monitored by the use of strain gauges or other suitable equipment.

.3 Type C independent tanks should be tested as follows :

.3.1 Each pressure vessel, when completely manufactured, should be subjected to a hydrostatic test at a pressure measured at the top of the tanks, of not less than 1.5 P0, but in no case during the pressure test should the calculated primary membrane stress at any point exceed 90% of the yield stress of the material.

The definition of P0 is given in 4.2.6. To ensure that this condition is satisfied where calculations indicate that this stress will exceed 0.75 times the yield strength, the prototype test should be monitored by the use of strain gauges or other suitable equipment in pressure vessels other than simple cylindrical and spherical pressure vessels.

.3.2 The temperature of the water used for the test should be at least 30°C above the nil ductility transition temperature of the material as fabricated.

.3.3 The pressure should be held for 2 h per 25 mm of thickness but in no case less than 2 h.

.3.4 Where necessary for cargo pressure vessels, and with the specific approval of the Society, a hydropneumatic test may be carried out under the conditions prescribed in 4.10.10.1, .2, and .3.

.3.5 Special consideration may be given by the Administration to the testing of tanks in which higher allowable stresses are used, depending on service temperature. However, the requirements of 4.10.10.1 should be fully complied with.

.3.6 After completion and assembly, each pressure vessel and its related fittings should be subjected to an adequate tightness test.

.3.7 Pneumatic testing of pressure vessels other than cargo tanks should only be considered on an individual case basis by the Administration. Such testing should be permitted only for those vessels which are so designed or supported that they cannot be safely filled with water, or for those vessels which cannot be dried and are to be used in a service where traces of the testing medium cannot be tolerated.

3.6.7 The insulation materials of internal insulation tanks should be subjected to additional inspection in order to verify their surface conditions after the third loaded voyage of the ship, but not later than the first 6 months of the ship’s service after building or major repair work is undertaken on the internal insulation tanks.

PROCESS PRESSURE VESSELS AND LIQUID, VAPOUR, AND PRESSURE PIPING SYSTEMS

Cargo and process piping
General

  • The requirements of sections 5.2 to 5.5 apply to product and process piping including vapor piping and vent lines of safety valves or similar piping. Instrument piping not containing cargo is exempt from these requirements.
  • Provision should be made by the use of offsets, loops, bends, mechanical expansion joints such as bellows, slip joints, and ball joints, or similar suitable means to protect the piping, piping system components, and cargo tanks from excessive stresses due to thermal movement and from movements of the tank and hull structure. Where mechanical expansion joints are used in piping they should be held to a minimum and, where located outside cargo tanks, should be of the bellows type.
  • Low-temperature piping should be thermally isolated from the adjacent hull structure, where necessary, to prevent the temperature of the hull from falling below the design temperature of the hull material. Where liquid piping is dismantled regularly, or where liquid leakage may be anticipated, such as at shore connections and at pump seals, protection for the hull beneath should be provided.
  • Where tanks or piping are separated from the ship’s structure by thermal isolation, provision should be made for electrically bonding both the piping and the tanks. All gasketed pipe joints and hose connections should be electrically bonded.
  • Suitable means should be provided to relieve the pressure and remove liquid contents from cargo loading and discharging crossover headers and cargo hoses to the cargo tanks or other suitable locations, prior to disconnecting the cargo hoses.
  • All pipelines or components which may be isolated in a liquid full condition should be provided
    with relief valves.
  • Relief valves discharging liquid cargo from the cargo piping system should discharge into the cargo tanks; alternatively, they may discharge to the cargo vent mast if means are provided to detect and dispose of any liquid cargo which may flow into the vent system. Relief valves on cargo pumps should discharge to the pump suction.

Materials

  • The choice and testing of materials used in piping systems should comply with the requirements of Chapter 6 taking into account the minimum design temperature. However, some relaxation may be permitted in the quality of the material of open-ended vent piping, provided the temperature of the cargo at the pressure relief valve setting is -55°C or greater and provided no liquid discharge to the vent piping can
    occur. Similar relaxations may be permitted under the same temperature conditions to open-ended piping inside cargo tanks, excluding discharge piping and all piping inside the membrane and semi-membrane tanks.
  • Materials having a melting point below 925°C should not be used for piping outside the cargo tanks except for short lengths of pipes attached to the cargo tanks, in which case fire-resisting insulation should be provided.

Piping fabrication and joining details

  • The requirements of the Article apply to piping inside and outside the cargo tanks. Relaxations from these requirements may be accepted, in accordance with recognized standards, for piping inside cargo tanks and open-ended piping.
  • The following direct connection of pipe lengths, without flanges, may be considered:

.1 Butt-welded joints with complete penetration at the root may be used in all applications. For design temperatures below -10°C, butt welds should be either double welded or equivalent to a double welded butt joint. This may be accomplished by use of a backing ring, consumable insert, or inert gas back-up on the first pass. For design pressures in excess of 10 bar and design temperatures of -10°C or lower, backing rings should be removed.

.2 Slip-on welded joints with sleeves and related welding, having dimensions in accordance with recognized standards should only be used for open-ended lines with an external diameter of 50 mm or less and design temperatures not lower than -55°C.

.3 Screwed couplings complying with recognized standards only be used for accessory lines and instrumentation lines with external diameters of 25 mm or less.

  • Flanges in flange connections should be of the welded neck, slip-on or socket welded type.
  • Flanges should be selected as to the type and made and tested in accordance with recognized standards. In particular, for all piping except open-ended, the following restrictions apply :

.1 For design temperatures lower than -55°C, only welded neck flanges should be used.
.2 For design temperatures lower than -10°C, slip-on flanges should not be used in nominal sizes above 100 mm and socket welded flanges should not be used in nominal sizes above 50 mm.

  • Piping connections, other than those mentioned in 5.4.2 and .3, may be accepted by the Administration in each case.
  • Bellows and expansion joints should be provided to allow for the expansion of piping.

.1 If necessary, bellows should be protected against icing.
.2 Slip joints should not be used except within the cargo tanks.

  • Welding, post-weld heat treatment, and non-destructive testing.

.1 Welding should be carried out in accordance with 6.3.

.2 Post-weld heat treatment should be required for all butt welds of pipes made with carbon, carbon manganese, and low alloy steels. The Administration may waive the requirement for thermal stress relieving of pipes having a wall thickness of less than 10 min in relation to the design temperature and pressure of the piping system concerned.

.3 In addition to normal controls before and during the welding and to the visual inspection of the finished welds, as necessary for proving that the welding has been carried out correctly and according to the requirements of this paragraph, the following tests should be required :

.3.1 100% radiographic inspection of butt welded joints for piping systems with design temperatures lower than -10°C and with inside diameters of more than 75 mm or wall thicknesses greater than 10 mm.

When such butt welded joints of piping sections are made by automatic welding procedures in the pipe fabrication shop, upon special approval by the Administration, the extent of radiographic inspection may be progressively reduced but in no case to less than 10% of each joint. If defects are revealed the extent of examination should be increased to 100% and should include inspection of previously accepted welds.

This special approval can only be granted if well-documented quality assurance procedures and records are available to enable the

Administration to assess the ability of the manufacturer to produce satisfactory welds consistently.

Cargo system valving requirements
(Paragraph 5.6.5 applies to ships constructed on or after 1 July 2002.)

  • Every cargo piping system and cargo tank should be provided with the following valves, as applicable:

.1 For cargo tanks with a MARVS not exceeding 0.7 bar gauge, all liquid and vapor connections, except safety relief valves and liquid level gauging devices, should have shutoff valves located as close to the tank as practicable. These valves may be remotely controlled but should be capable of local manual operation and provide full closure. One or more remotely controlled emergency shutdown valves should be provided on the ship for shutting down the liquid and vapor cargo transfer between the ship and the shore. Such valves may be arranged to suit the ship’s design and may be the same valve as required in 5.6.3 and should comply with the requirements of 5.6.4.

.2 For cargo tanks with a MARVS exceeding 0.7 bar gauge, all liquid and vapor connections, except safety relief valves and liquid level gauging devices, should be equipped with a manually operated stop valve and a remotely controlled emergency shutdown valve. These valves should be located as close to the tank as practicable. Where the pipe size does not exceed 50 mm in diameter, excess flow valves may be used in lieu of the emergency shutdown valve. A single valve may be substituted for the two separate valves provided the valve complies with the requirements of 5.6.4, is capable of local manual operation, and provides full closure of the line.

  • Cargo tank connections for gauging or measuring devices need not be equipped with excess flow or emergency shutdown valves provided that the devices are so constructed that the outward flow of tank contents cannot exceed that passed by a 1.5 mm diameter circular hole.
  • One remotely operated emergency shutdown valve should be provided at each cargo hose connection in use. Connections not used in transfer operations may be blinded with blank flanges in lieu of valves.
  • The control system for all required emergency shutdown valves should be so arranged that all such valves may be operated by single controls situated in at least two remote locations on the ship. One of these locations should be the control position required by 13.1.3 or the cargo control room. The control system should also be provided with fusible elements designed to melt at temperatures between 98 °Cand 104 °C which will cause the emergency shutdown valves to close in the event of a fire. Locations for such fusible elements should include the tank domes and loading stations. Emergency shutdown valves should be of the fail-closed (closed on loss of power) type and be capable of local manual closing operation.
  • Emergency shutdown valves in liquid piping should fully close under all service conditions within 30 s of actuation as measured from the time of manual or automatic initiation to final closure. This is called the total shutdown time and is made up of a signal response time and a valve closure time. The valve closure time should be such as to avoid surge pressures in pipelines. Information about the closing time of the valves and their operating characteristics should be available on board and the valve closure time should be verifiable and reproducible. Such valves should close in such a manner as to cut off the flow smoothly.
  • The closure time of the 30s for the emergency shutdown valve referred to in 5.6.4 should be measured from the time of manual or automatic initiation to final closure. This is called the total shutdown time and is made up of a signal response time and a valve closure time. The valve closure time should be such as to avoid surge pressure in pipelines. Such valves should close in such a manner as to cut off the flow smoothly.
  • Excess flow valves should close automatically at the rated closing flow of vapor or liquid as specified by the manufacturer. The piping including fittings, valves, and appurtenances protected by an excess flow valve, should have a greater capacity than the rated closing flow of the excess flow valve.

Excess flow valves may be designed with a bypass not exceeding an area of 1.0 mm diameter circular opening to allow equalization of pressure, after an operating shutdown.

Ship’s cargo hoses

  • Liquid and vapor hoses used for cargo transfer should be compatible with the cargo and suitable for the cargo temperature.
  • Hoses subject to tank pressure, or the discharge pressure of pumps or vapor compressors, should be designed for a bursting pressure not less than 5 times the maximum pressure the hose will be subjected to during cargo transfer.
  • For cargo hoses installed on board ships on or after 1 July 2002, each new type of cargo hose, complete with end-fittings, should be prototype-tested at a normal ambient temperature with 200 pressure cycles from zero to at least twice the specified maximum working pressure. After this cycle pressure test has been carried out, the prototype test should demonstrate a bursting pressure of at least 5 times its specified maximum working pressure at the extreme service temperature. Hoses used for prototype testing should not be used for cargo service. Thereafter, before being placed in service, each new length of cargo hose produced should be hydrostatically tested at ambient temperature to a pressure not less than 1.5 times its specified maximum working pressure but not more than two-fifths of its bursting pressure. The hose should be stenciled or otherwise marked with the date of testing, its specified maximum working pressure and if used in services other than the ambient temperature services, its maximum and minimum service temperature, as applicable. The specified maximum working pressure should not be less than 10 bar gauges.Cargo transfer methods
  • Where cargo transfer is by means of cargo pumps not accessible for repair with the tanks in service, at least two separate means should be provided to transfer cargo from each cargo tank, and the design should be such that the failure of one cargo pump, or means of transfer, will not prevent the cargo transfer by another pump or pumps, or other cargo transfer means.
  • The procedure for the transfer of cargo by gas pressurization should preclude the lifting of the relief valves during such transfer. Gas pressurization may be accepted as a means of transfer of cargo for those tanks so designed that the design factor of safety is not reduced under the conditions prevailing during the cargo transfer operation.

Vapour return connexions

Connections for vapor return lines to the shore installations should be provided.

MATERIALS OF CONSTRUCTION

  • This Chapter gives the requirements for plates, sections, pipes, forgings, castings, and weldments used in the construction of cargo tanks, cargo process pressure vessels, cargo, and process piping, secondary barriers, and contiguous hull structures associated with the transportation of the products. The requirements for rolled materials, forgings, and castings are given in 6.2 and tables 6.1 to 6.5. The
    requirements for weldments are given in 6.3.
  •  The manufacture, testing, inspection, and documentation should be in accordance with Recognized Standards and the specific requirements given in this Code.
  • The bend test may be omitted as a material acceptance test, but is required for weld tests.
  • Materials with alternative chemical compositions or mechanical properties may be accepted by the Administration.
  • Where post-weld heat treatment is specified or required, the properties of the base material should be determined in the heat-treated condition in accordance with the applicable table of this Section and the weld properties should be determined in the heat-treated condition in accordance with 6.3. In cases where a post-weld heat treatment is applied, the test requirements may be modified at the discretion of the Administration.

Welding and non-destructive testing

  • General

The requirements of this section are those generally employed for carbon, carbon-manganese, nickel alloy, and stainless steels, and may form the basis for acceptance testing of other materials. At the discretion of the Administration, impact testing of stainless steel and aluminum alloy weldments may be omitted and other tests may be specially required for any material.

  • Welding consumables

Welding consumables intended for welding cargo tanks should be in accordance with Recognized Standards unless otherwise agreed with the Administration. Deposited weld metal tests and butt weld tests should be required for all welding consumables, unless otherwise specially agreed with the Administration. The results obtained from tensile and Charpy V-notch impact tests should be in accordance with Recognized Standards. The chemical composition of the deposited weld metal should be recorded for information and approval.

  • Welding procedure tests for cargo tanks and process pressure vessels

Welding procedure tests for cargo tanks and process pressure vessels are required for all butt welds and the test assemblies should be representative of :

– each base material
– each type of consumable and welding process
– each welding position.

For butt welds in plates, the test assemblies should be so prepared that the rolling direction is parallel to the direction of welding. The range of thickness qualified by each welding procedure test should be in accordance with Recognized Standards. Radiographic or ultrasonic testing may be performed at the option of the fabricator or the Administration. Procedure tests for consumables intended for fillet welding procedure tests should be in accordance with Recognized Standards. In such cases, consumables should be selected that exhibit satisfactory impact properties.

  • The following welding procedure tests for cargo tanks and process pressure vessels should be made from each test assembly:

.1 Cross-weld tensile tests.
.2 Transverse bend tests which may be facing, root, or side bends at the discretion of the Administration.

However, longitudinal bend tests may be required in lieu of transverse bend tests in cases where the base material and weld metal have different strength levels.

.3 One set of three Charpy V-notch impacts, generally at each of the following locations, as shown in figure 6.1:
Centreline of the welds
Fusion line (F.L.)

1 mmfrom the F.L.
3 mmfrom the F.L.
5 mmfrom the F.L

.4 Macro section, microsection, and hardness survey may also be required by the Administration.

  • Test requirements

.1 Tensile tests: Generally, tensile strength should not be less than the specified minimum tensile strength for the appropriate parent materials. The Administration may also require that the transverse weld tensile strength should not be less than the specified minimum tensile strength for the weld metal, where the weld metal has a lower tensile strength than that of the parent metal. In every case, the position
of fracture is to be reported for information.

.2 Bend tests: No fracture is acceptable after a 180° bend over a former of diameter 4 times the thickness of the test pieces, unless otherwise especially required by or agreed with the Administration.

.3 Charpy V-notch impact tests: Charpy tests should be conducted at the temperature prescribed for the base material being joined. The results of weld metal impact tests, minimum average energy (E), should be no less than 27 J. The weld metal requirements for subsidized specimens and single energy values should be in accordance with 6.1.4. The results of fusion line and heat-affected zone impact tests should show minimum average energy (E) in accordance with the transverse or longitudinal requirements of the base material, whichever is applicable, and for subsidized specimens, the minimum average energy (E) should be in accordance with 6.1.4. If the material thickness does not permit machining of either full-size or standard to subsidize specimens, the testing procedure and acceptance standards should be in accordance with Recognized Standards.

.4 Welding procedure tests for piping

Welding procedure tests for piping should be carried out and should be similar to those detailed for cargo tanks.

  • Production weld tests

.1 For all cargo tanks and process pressure vessels except integral and membrane tanks, production weld tests should generally be performed for approximately each 50 m of butt weld joints and should be representative of each welding position. For secondary barriers, the same type of production tests as required for primary tanks should be performed except that the number of tests may be reduced subject to agreement with the Administration. Tests, other than those specified in 6.3.6.2, .3, and .4, may be required for cargo tanks or secondary barriers at the discretion of the Administration.

.2 The production tests for types A and B independent tanks and semi-membrane tanks should include the following tests :

a.  Bend tests, and were required for procedure tests one set of three Charpy V-notch tests should be made for every 50 m of the weld. The Charpy V-notch tests should be made with specimens having the notch alternately located in the center of the weld and in the heat-affected zone (the most critical location based on procedure qualification results). For austenitic stainless steel, all notches should be in the center of the weld.

b. The test requirements are the same as the applicable test requirements listed, except that impact tests that do not meet the prescribed energy requirements may still be accepted, upon special consideration by the Administration, by passing a drop weight test. In such cases, two drop weight specimens should be tested for each set of Charpy specimens that failed and both must show “no break” performance at the temperature at which the Charpy tests were conducted.

  • for type C independent tanks and process pressure vessels, transverse weld tensile tests are required. The test requirements are listed in 6.3.4 except that impact tests that do not meet the prescribed energy requirements may still be accepted upon special consideration by the Administration, by passing a drop weight test. In such cases, two drop weight specimens should be tested for each set of Charpy specimens that failed, and both must show “no break” performance at the temperature at which the Charpy tests were conducted.

3. Non-destructive testing

a. For type A independent tanks and semi-membrane tanks where the design temperature is -20°C or less, and for type B independent tanks regardless of temperature, all full penetration butt welds of the shell plating of cargo tanks should be subjected to 100% radiographic inspection.

b. Where the design temperature is higher than -20°C, all full penetration butt welds in way of intersections and at least 10% of the remaining full penetration welds of tank structures should be subjected to radiographic inspection.

c. In each case the remaining tank structure including the welding of stiffeners and other fittings and attachments should be examined by magnetic particle or dye penetrant methods as considered necessary by the Administration.

d. All test procedures and acceptance standards should be in accordance with Recognized Standards. The Administration may accept an approved ultrasonic test procedure in lieu of radiographic inspection, but may in addition require supplementary inspection by radiography at selected locations.

Further, the Administration may require ultrasonic testing in addition to normal radiographic inspection.

CARGO TANK VENT SYSTEMS

  • General

All cargo tanks should be provided with a pressure relief system appropriate to the design of the cargo containment system and the cargo being carried. Hold spaces, intercarrier spaces, and cargo piping which may be subject to pressures beyond their design capabilities should also be provided with a suitable pressure relief system. The pressure relief system should be connected to a vent piping system so designed to minimize the possibility of cargo vapor accumulating on the decks, or entering accommodation spaces, service spaces, control stations, machinery spaces, or other spaces where it may create a dangerous condition. Pressure control systems specified by Chapter 7 should be independent of the pressure relief valves.

Pressure relief systems

  • Each cargo tank with a volume exceeding 20 m³ should be fitted with at least two pressure relief valves of approximately equal capacity, suitably designed and constructed for the prescribed service. For cargo tanks with a volume not exceeding 20 m³, a single relief valve may be fitted
  • Interbarrier spaces should be provided with pressure relief devices complying with recognized standards.
  • In general, the setting of the pressure relief valves should not be higher than the vapor pressure which has been used in the design of the tank. However, where two or more pressure relief valves are fitted, valves comprising not more than 50% of the total relieving capacity may be set at a pressure up to 5% above MARVS.
  • Pressure relief valves should be connected to the highest part of the cargo tank above deck level.
    Pressure relief valves on cargo tanks with a design temperature below 0 °C should be arranged to prevent their becoming inoperative due to ice formation when they are closed. Due consideration should be given to the construction and arrangement of pressure relief valves on cargo tanks subject to low ambient temperatures. Valves should be constructed of materials with a melting point above 925 °C.
    Consideration of lower melting point materials for internal parts and seals should be given if their use provides significant improvement to the general operation of the valve.
  • Pressure relief valves should be prototype tested to ensure that the valves have the capacity required.
    Each valve should be tested to ensure that it opens at the prescribed pressure setting with an allowance not exceeding ±10% for 0 to 1.5 bar,±6% for 1.5 to 3.0 bar, and ±3% for 3.0 bar and above. Pressure relief valves should be set and sealed by a competent authority acceptable to the Administration and a record of this action, including the values of set pressure, should be retained aboard the ship.
  • In the case of cargo tanks permitted to have more than one relief valve setting, this may be accomplished by :

.1 installing two or more properly set and sealed valves and providing means as necessary for isolating the valves, not in use from the cargo tank; or

.2 installing relief valves whose settings may be changed by the insertion of the previously approved spacer pieces or alternative springs or by other similar means not requiring pressure testing to verify the new set pressure. All other valve adjustments should be sealed.

  • The changing of the set pressure under the provisions of 8.2.6, and the corresponding resetting of the alarms referred to in 13.4.1, should be carried out under the supervision of the master in accordance with procedures approved by the Administration and specified in the ship’s operating manual. Changes in set pressures should be recorded in the ship’s log and a sign posted in the cargo control room, if provided, and at each relief valve, stating the set pressure.
  • Stop valves or other means of blanking off pipes between tanks and pressure relief valves to facilitate maintenance should not be fitted unless all the following arrangements are provided :

.1 suitable arrangement to prevent more than one pressure relief valve from being out of service at the same time ;

.2 a device which automatically and in a clearly visible way indicates which one of the pressure relief valves is out of service; and

.3 pressure relief valve capacities such that if one valve is out of service the remaining valves have the combined relieving capacity required by 8.5. However, this capacity may be provided by the combined capacity of all valves, if a suitably maintained spare valve is carried on board.

Vacuum protection systems

  • Cargo tanks are designed to withstand a maximum external pressure differential exceeding 0.25 bar and are capable of withstanding the maximum external pressure differential which can be attained at maximum discharge rates with no vapor return into the cargo tanks, or by operation of a cargo refrigeration system, needed no vacuum relief protection.
  • Cargo tanks designed to withstand a maximum external pressure differential not exceeding 0.25 bar, or tanks that cannot withstand the maximum external pressure differential that can be attained at maximum discharge rates with no vapor return into the cargo tanks, or by operation of a cargo refrigeration system, or by sending boil-off vapor to the machinery spaces, should be fitted with :

.1 two independent pressure switches sequentially alarm and subsequently, stop all suction of cargo liquid or vapor from the cargo tank, and refrigeration equipment if fitted, by suitable means at a pressure sufficiently below the maximum external designed pressure differential of the cargo tank; or

.2 vacuum relief valves with a gas flow capacity at least equal to the maximum cargo discharge rate per cargo tank, set to open at a pressure sufficiently below the external design differential pressure of the cargo tank; or

.3 other vacuum relief systems acceptable to the Administration.

Vacuum protection systems

  • Cargo tanks are designed to withstand a maximum external pressure differential exceeding 0.25 bar and are capable of withstanding the maximum external pressure differential which can be attained at maximum discharge rates with no vapor return into the cargo tanks, or by operation of a cargo refrigeration system, needed no vacuum relief protection.
  • Cargo tanks designed to withstand a maximum external pressure differential not exceeding 0.25 bar, or tanks that cannot withstand the maximum external pressure differential that can be attained at maximum discharge rates with no vapor return into the cargo tanks, or by operation of a cargo refrigeration system, or by sending boil-off vapor to the machinery spaces, should be fitted with :

.1 two independent pressure switches sequentially alarm and subsequently, stop all suction of cargo liquid or vapor from the cargo tank, and refrigeration equipment if fitted, by suitable means at a pressure sufficiently below the maximum external designed pressure differential of the cargo tank; or

.2 vacuum relief valves with a gas flow capacity at least equal to the maximum cargo discharge rate per cargo tank, set to open at a pressure sufficiently below the external design differential pressure of the cargo tank; or

.3 other vacuum relief systems acceptable to the Administration.

  • Subject to the requirements of Chapter 17, the vacuum relief valves should admit an inert gas, cargo vapor, or air to the cargo tank and should be arranged to minimize the possibility of the entrance of water or snow. If cargo vapor is admitted, it should be from a source other than the cargo vapor lines.
  • The vacuum protection system should be capable of being tested to ensure that it operates at the prescribed pressure.

ENVIRONMENTAL CONTROL

  • Environmental control within cargo tanks and cargo piping systems

.1 A piping system should be provided to enable each cargo tank to be safely gas-freed and to be safely purged with cargo gas from a gas-free condition. The system should be arranged to minimize the possibility of pockets of gas or air remaining after gas-freeing or purging.

.2 A sufficient number of gas sampling points should be provided for each cargo tank in order to adequately monitor the progress of purging and gas-freeing. Gas sampling connections should be valved and capped above the main deck.

.3 For flammable gases, the system should be arranged to minimize the possibility of a flammable mixture existing in the cargo tank during any part of the gas-freeing operation by utilizing an inerting medium as an intermediate step. In addition, the system should enable the cargo tank to be purged with an inerting medium prior to filling with cargo vapor or liquid, without permitting a flammable mixture to
exist at any time within the cargo tank.

.4 Piping systems which may contain cargo should be capable of being gas-freed and purged as provided in 7.1.1 and 7.1.3.

.5 Inert gas utilized in these procedures may be provided from the shore or from the ship.

  • Environmental control within the hold spaces (cargo containment systems other than type C independent tanks)

.1 Interbarrier and hold spaces associated with cargo containment systems for flammable gases requiring full secondary barriers should be inserted with a suitable dry inert gas and kept inerted with make-up gas provided by a shipboard inert gas generation system, or by shipboard storage which should be sufficient for normal consumption for at least 30 days.

Inter-barrier and hold spaces associated with cargo containment systems for flammable gases requiring partial secondary barriers should be inserted with suitable dry inert gas and kept inerted with makeup gas provided by a shipboard inert gas generation system or by shipboard storage which should be sufficient for normal consumption for at least 30 days; alternatively

  • Environmental control of spaces surrounding type C independent tanks

Spaces surrounding refrigerated cargo tanks not having secondary barriers should be filled with suitable
dry inert gas or dry air and be maintained in this condition with make-up inert gas provided by a ship board inert gas generation system, shipboard storage of inert gas, or dry air provided by suitable air
drying equipment.

Inerting

  • Inerting refers to the process of providing a noncombustible environment by the addition of compatible gases, which may be carried in storage vessels or produced on board the ship, or supplied from the shore. The inert gases should be compatible chemically and operationally, at all temperatures likely to occur within the spaces to be inserted, with the materials of construction of the spaces and the cargo. The dew points of the gases should be taken into consideration.
  • Where inert gas is also stored for fire-fighting purposes, it should be carried in separate containers and should not be used for cargo services.
  • Where inert gas is stored at a temperature below 0°C, either as a liquid or as a vapor, the storage and supply system should be so designed that the temperature of the ship’s structure is not reduced below the limiting values imposed on it.
  • Arrangements suitable for the cargo carried should be provided to prevent the backflow of cargo vapor into the inert gas system.
  • The arrangements should be such that each space being inserted can be isolated and the necessary controls and relief valves etc. should be provided for controlling pressure in these spaces.

Inert gas production on board

  • The equipment should be capable of producing inert gas with an oxygen content at no time greater than 5% by volume subject to the special requirements of Chapter 17. A continuous-reading oxygen content meter should be fitted to the inert gas supply from the equipment and should be fitted with an alarm set at a maximum of 5% oxygen content by volume subject to the requirements of Chapter 17.

Additionally, where inert gas is made by an on-board process of fractional distillation of air which involves the storage of the cryogenic liquefied nitrogen for subsequent release, the liquefied gas entering the storage vessel should be monitored for traces of oxygen to avoid possible initial high oxygen enrichment of the gas when released for inerting purposes.

  • An inert gas system should have pressure controls and monitoring arrangements appropriate to the cargo containment system. A means acceptable to the administration, located in the cargo area, of preventing the backflow of cargo gas should be provided.
  • Spaces containing inert gas generating plants should have no direct access to accommodation spaces, service spaces, or control stations, but may be located in machinery spaces. If such plants are located in machinery spaces or other spaces outside the cargo area, two non-return valves, or equivalent devices should be fitted in the inert gas main in the cargo area as required in 9.5.2. Inert gas piping should
    not pass through accommodation spaces, service spaces, or control stations. When not in use, the inert gas system should be made separate from the cargo system in the cargo area except for connections to the hold spaces or intercarrier spaces.
  • Flame-burning equipment for generating inert gas should not be located within the cargo area. Special consideration may be given to the location of inert gas generating equipment using the catalytic combustion process.

PERSONNEL PROTECTION

  • Protective equipment

For the protection of crew members engaged in loading and discharging operations, suitable protective equipment including eye protection should be provided, taking into account the character of the products.

Safety equipment

  • Sufficient, but not less than two complete sets of safety equipment in addition to the firemen’s outfits required by 11.6.1 each permitting personnel to enter and work in a gas-filled space, should be provided.
  • One complete set of safety equipment should consist of:

.1 oneself-contained air-breathing apparatus not using stored oxygen, having a capacity of at least 1,200 l of free air;
.2 protective clothing, boots, gloves, and tight-fitting goggles ;
.3 steel-cored rescue line with a belt; and
.4 explosion-proof lamp.

First aid equipment

  • A stretcher that is suitable for hoisting an injured person from spaces below deck should be kept in a readily accessible location.
  • The ship should have on board medical first-aid equipment, including oxygen resuscitation equipment and antidotes for cargoes to be carried, based on the guidelines developed by the Organization*.
    * Reference is made to the Medical First Aid Guide for Use in Accidents Involving Dangerous Goods (MFAG), which provides advice on the treatment of casualties in accordance with the symptoms exhibited as well as equipment and antidotes that may be appropriate for treating the casualty

Personal protection requirements for individual products

  • Provisions of 14.4 are applicable to ships carrying products for which those paragraphs are listed in the column “i” in the table of Chapter 19.
  • Respiratory and eye protection suitable for emergency escape purposes should be provided for every
    the person on board is subject to the following :

.1 filter type respiratory protection should be accepted, only when one filter is suitable for all designated cargoes that the ship is certified to carry;

.2 self-contained breathing apparatus should normally have a duration of service of at least 15 min ;

a.  emergency escape respiratory protection should not be used for fire-fighting or cargo handling purposes and should be marked to that effect ;

b. two additional sets of the above respiratory and eye protection should be permanently located in the navigating bridge.

  • Suitably marked decontamination showers and an eyewash should be available on deck in convenient locations.

.1 In ships of a cargo capacity of 2,000 m³ and over, two complete sets of safety equipment should be provided in addition to the equipment required by 11.6.1 and 14.2.1. At least three spare charged air bottles should be provided for each self-contained air-breathing apparatus required in this paragraph.

USE OF CARGO AS FUEL

  • General
  1. Methane (LNG) is the only cargo whose vapor or boil-off gas may be utilized in machinery spaces of category A and in such spaces may be utilized only in boilers, inert gas generators, combustion engines, and gas turbines.
  • Arrangement of machinery spaces of category A

1. Spaces in which gas fuel is utilized should be fitted with a mechanical ventilation system and should be arranged in such a way as to prevent the formation of dead spaces. Such ventilation should be particularly effective in the vicinity of electrical equipment and machinery or of other equipment and machinery which may generate sparks. Such a ventilation system should be separated from those intended for other spaces.

2. Gas detectors should be fitted in these spaces, particularly in the zones where air circulation is reduced. The gas detection system should comply with the requirements of chapter 13

Gas fuel supply

  • Gas fuel piping should not pass through accommodation spaces, service spaces, or control stations. Gas fuel piping may pass through or extend into other spaces provided they fulfill one of the following :

.1 the gas fuel piping should be a double wall piping system with the gas fuel contained in the inner pipe.

The space between the concentric pipes should be pressurized with inert gas at a pressure greater than the gas fuel pressure. Suitable alarms should be provided to indicate a loss of inert gas pressure between the pipes; or

.2 the gas fuel piping should be installed within a ventilated pipe or duct. The air space between the gas fuel piping and the inner wall of this pipe or duct should be equipped with mechanical exhaust ventilation having a capacity of at least 30 air changes per hour. The ventilation system should be arranged to maintain a pressure less than the atmospheric pressure. The fan motors should be placed outside the ventilated pipe or duct. The ventilation outlet should be placed in a position where no flammable gas-air mixture may be ignited. The ventilation should always be in operation when there is gas fuel in the piping. Continuous gas detection should be provided to indicate leaks and to shut down the gas fuel supply to the machinery space in accordance with 16.3.10 The master gas fuel valve required by 16.3.7 should close automatically if the required airflow is not established and maintained by the exhaust ventilation system.

OPERATING REQUIREMENTS

Cargo information

  • Information should be on board and available to all concerned, giving the necessary data for the safe carriage of cargo. Such information should include for each product carried:

.1 a full description of the physical and chemical properties necessary for the safe containment of the cargo ;
.2 action to be taken in the event of spills or leaks ;
.3 counter-measures against accidental personal contact ;
.4 fire-fighting procedures and fire-fighting media ;
.5 procedures for cargo transfer, gas-freeing, ballasting, tank cleaning, and changing cargoes;
.6 special equipment needed for the safe handling of the particular cargo ;
.7 minimum allowable inner hull steel temperatures; and
.8 emergency procedures.

Compatibility

  • The master should ascertain that the quantity and characteristics of each product to be loaded are within the limits indicated in the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk provided in 1.5 and in the Loading and Stability Information booklet provided in 2.2.5 and that products are listed in the International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk as required under section 3 of the Certificate.
  • Care should be taken to avoid dangerous chemical reactions if cargoes are mixed. This is of particular significance in respect of:

.1 tank cleaning procedures required between successive cargoes in the same tank; and

.2 simultaneous carriage of cargoes which react when mixed. This should be permitted only if the complete cargo systems including, but not limited to, cargo pipework, tanks, and vent refrigeration systems are physically separate.

Personnel training

* Reference is made to the provisions of the International Convention on Standards of Training, Certification and Watchkeeping for seafarers, 1978 and in particular to the “Mandatory Minimum Requirements for the Training and Qualifications of Masters, Officers, and Ratings of Chemical Tankers”

– Regulation V/2, Chapter V of the Annex to that Convention and to Resolution 11 of the International Conference on Training and Certification of Seafarers, 1978.

  • Personnel involved in cargo operations should be adequately trained in handling procedures.
  • All personnel should be adequately trained in the use of protective equipment provided on board and have basic training in the procedures, appropriate to their duties, and necessary under emergency conditions.
  • Officers should be trained in emergency procedures to deal with conditions of leakage, spillage, or fire involving the cargo, based on the guidelines developed by the Organization*, and a sufficient number of them should be instructed and trained in essential first aid for cargo carried.
    * Refer to the Medical First Aid Guide for Use in Accidents Involving Dangerous Goods (MFAG), which provides advice on the treatment of casualties in accordance with the symptoms exhibited as well as equipment and antidotes that may be appropriate for treating the casualty, and to the relevant provisions of STCW Code, parts A and B..

Cargo transfer operations

  • Transfer operations including emergency procedures should be discussed between ship personnel and the persons responsible at the shore facility prior to commencement and communications maintained throughout the transfer operations.
  • The closing time of the valve referred to in 13.3.1 (i.e. time from shutdown signal initiation to complete valve closure) should not be greater than :

3600 U/LR (s)
where: U = ullage volume at operating signal level (m³)
LR= maximum loading rate agreed between ship and shore facility (m³/h).

The loading rate should be adjusted to limit surge pressure on valve closure to an acceptable level taking into account the loading hose or arm, the ship, and the shore piping systems where relevant.

Exam Questions

3. The structure, equipment, fittings, arrangements and material (other than items in respect of which a Cargo Ship Safety Construction Certificate, Cargo Ship Safety Equipment Certificate and Cargo Ship Safety Radio Certificate or Cargo Ship Safety Certificate are issued) of a gas carrier should be subjected to the following surveys:

4. Ships subject to the IGC Code should be designed to one of the following standards:

5. Shipside discharges below the freeboard deck: The provision and control of valves fitted to discharges led through the shell from spaces below the freeboard deck or from within the superstructures and deckhouses on the freeboard deck fitted with weathertight doors should comply with the requirements of the relevant regulation of the International Convention on Load Lines in force, except that the choice of valves should be limited to:

6. Cargo tanks should be located at the following distances inboard:

9. Any cargo control room should be above the weather deck and may be located in the cargo area. The cargo control room may be located within the accommodation spaces, service spaces or control stations provided the following conditions are complied with:

10. Access to spaces in the cargo area should be provided to

13. Every cargo piping system and cargo tank should be provided with the following valves, as applicable:

15. The refrigeration system may be arranged in one of the following ways:

17. Safety equipment: Sufficient, but not less than two complete sets of safety equipment in addition to the firemen's outfits, permitting personnel to enter and work in a gas-filled space, should be provided. One complete set of safety equipment should consist of: