IGC Code: Construction of Gas Carriers

Background

Origin and legal status

The IGC Code traces its lineage to the early 1970s, when the rapid expansion of LNG and LPG seaborne trade prompted IMO to develop a coherent regulatory framework for what had previously been governed by a patchwork of class-society rules and national regulations. The first IGC Code was adopted by IMO Resolution MSC.5(48) in 1983 and entered into force on 1 July 1986, applying to ships built on or after that date. Earlier vessels (those built between October 1976 and 1 July 1986) fell under the older GC Code (Gas Carrier Code) adopted by Resolution A.328(IX); ships built between 1968 and 1976 were governed by the Existing Gas Carrier Code (EGC Code) of Resolution A.329(IX). The three-way split (EGC / GC / IGC) reflects the rapid evolution of gas-carrier technology and the IMO’s reluctance to apply new construction standards retrospectively.

The IGC Code derives its mandatory force from SOLAS Chapter VII Part C (Construction and Equipment of Ships Carrying Liquefied Gases in Bulk), Regulation 11, which requires every chemical or gas carrier to comply with the appropriate code. SOLAS Chapter VII Part C entered into force in this form on 1 July 1986 as part of the package of amendments adopted at the 1983 IMO conference.

The 2014 rewrite

After three decades of amendments, the IMO undertook a comprehensive rewrite of the IGC Code to reflect post-1980s developments in cryogenic engineering, cargo containment, and process safety. The rewritten Code was adopted by IMO Resolution MSC.370(93) in May 2014 and entered into force on 1 January 2016, applying to ships whose contract is placed on or after that date (or, in the absence of a building contract, ships whose keel is laid on or after 1 July 2016, or which are delivered on or after 1 January 2020). Pre-2016 ships continue to be governed by the pre-2014 version of the Code. The 2016 IGC Code is therefore in active use for new tonnage while a substantial fleet remains under the 1986/amended Code.

The 2014 rewrite preserved the structure of the original IGC Code (the same chapter numbering, the same four ship types, the same containment-system taxonomy) but tightened many provisions: more stringent definition of secondary barriers, expanded inerting requirements, mandatory two-stage emergency shutdown systems, expanded segregation requirements between cargo systems and machinery spaces, and explicit provisions for dual-fuel propulsion using cargo as fuel (which had emerged commercially in the 1990s but was not addressed in the original Code).

Scope of the IGC Code

The Code applies to vessels carrying any of the liquefied gases listed in Chapter 19 of the Code: methane (the principal LNG component), ethane, ethylene, propane, butane, butadiene, isoprene, propylene, vinyl chloride monomer (VCM), ethylene oxide, propylene oxide, ammonia, chlorine, and a long tail of specialty chemical-gas cargoes. Each cargo’s entry in Chapter 19 specifies the minimum ship type required, the independent tank type (where applicable), and any special carriage requirements (refrigeration regime, materials, additional inerting). A ship’s Certificate of Fitness lists every cargo it is approved to carry.

The Code does not apply to ships carrying liquid petroleum products at ambient temperature and atmospheric pressure (those are governed by SOLAS Chapter II-2 Part B and MARPOL Annex I) or to chemicals at ambient temperature (governed by the IBC Code under SOLAS Chapter VII Part B). The IGC Code’s defining feature is cryogenic or pressurised carriage of substances that are gaseous at ambient conditions, substances whose normal-boiling-point temperature is below the temperature at which they would be carried as a stable liquid.

Relationship to the IGF Code

The IGF Code (International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels), adopted by Resolution MSC.391(95) in June 2015 and entering into force 1 January 2017, addresses ships using gas as fuel, distinct from ships carrying gas as cargo. The IGF Code applies to dual-fuel propulsion, LNG-fuelled passenger and container ships, methanol-fuelled vessels, ammonia-fuelled vessels and similar arrangements. The two codes share many design principles (gas-tight segregation, leak detection, ESD architecture) and are explicitly cross-referenced. A vessel that carries LNG as cargo AND uses LNG as fuel (a typical modern LNG carrier with dual-fuel propulsion) complies with both codes.

The four ship types

Type 1G

Type 1G ships carry the most hazardous cargoes, those whose escape would present the greatest risk of severe harm to persons, the environment, or the ship. The Code requires Type 1G ships to have:

• Maximum cargo-tank capacity of 1,250 m³ per tank (limiting the consequence of any single tank rupture)
• Cargo tanks at least B/5 from the side shell (inboard) and B/15 from the keel, keeping cargo away from collision and grounding penetration zones, where B is the breadth of the ship
• Two independent means of cargo handling (separate pumps, separate piping)
• Stricter survival criteria in damage stability
• Maximum cargo capacity restrictions that effectively limit Type 1G ships to about 30,000 m³ total

In practice, Type 1G ship type is required for chlorine carriage. Chlorine has been carried in only a handful of dedicated specialty ships throughout the history of the gas-carrier industry; it is the most demanding cargo from a regulatory perspective.

Type 2G

Type 2G ships carry hazardous cargoes that nevertheless do not require the full Type 1G regime:

• Maximum cargo-tank capacity 8,000 m³ per tank
• B/5 inboard, B/15 above keel
• Two independent cargo handling means (slightly relaxed vs Type 1G)
• Survival criteria less stringent than Type 1G but still strict

Type 2G is the dominant ship type for the modern fleet. LNG carriers (methane), ethylene carriers, and ammonia carriers are all Type 2G. The vast majority of liquefied-gas tonnage worldwide is Type 2G, perhaps 600 LNG carriers and 1,500+ LPG/chemical-gas carriers.

Type 2PG

Type 2PG is a sub-category of Type 2G applicable to ships carrying cargoes at design pressures at or above 7 bar gauge with cargo tanks designed for at or above -55°C but with independent cargo tanks of Type C only (pressure vessels rather than refrigerated atmospheric tanks). The 2PG regime is principally used for fully refrigerated LPG carriers and semi-refrigerated carriers.

The “P” denotes that the cargo tank is a pressure vessel (Type C) rather than a refrigerated atmospheric tank (Type A or B), which simplifies several aspects of the survival and protection regime.

Type 3G

Type 3G is the least restrictive type, applicable to ships carrying the least hazardous cargoes (some grades of butane, propane, butadiene, vinyl chloride monomer in some configurations). The damage-stability and tank-protection criteria are less stringent than Type 2G. Type 3G ships are uncommon; the bulk of the LPG fleet is Type 2G or 2PG.

Determining ship type for a specific cargo

The IGC Code Chapter 19 lists every approved cargo with its required ship type. A vessel must be at least the type required for the most hazardous cargo it carries. For example, an LPG carrier may be Type 2PG, in which case it can carry propane, butane, and butadiene (Type 3G or 2PG cargoes) but cannot carry ammonia (Type 2G cargo) without a higher classification. The Certificate of Fitness lists the approved cargo types for each specific ship.

The IGC Tank Type calculator provides the type-classification logic for the four containment-system types (Type A/B/C/Membrane), which are distinct from the four ship types (1G/2G/2PG/3G).

Cargo containment systems

The IGC Code recognises four cargo containment system types, each with its own design philosophy, materials, and operational characteristics. The choice of containment system is a fundamental design decision driven by the cargo (LNG vs LPG vs ammonia), the trade route (long-distance vs short-sea), the loading-port and discharge-port restrictions, and the shipyard’s licensing arrangements.

Independent Type A tanks

Type A independent tanks are prismatic, self-supporting tanks designed using ordinary ship-structure methods (allowable stresses calculated using maritime classification society rules). Type A tanks are typically constructed of 9% nickel steel for LNG service or standard structural steel for LPG (where the cargo temperature is much higher). The defining feature is the requirement for a complete secondary barrier (an outer containment that can hold the entire cargo for at least 15 days in the event of a primary-barrier failure).

Type A tanks were used in some early LNG and LPG carriers. They have been largely displaced by Type B and Type C in modern construction because the full secondary barrier is space-inefficient and expensive.

Independent Type B tanks

Type B independent tanks are designed using refined methods of stress analysis (finite element analysis, fracture mechanics) that demonstrate the tank can survive credible damage scenarios with leakage rather than catastrophic rupture. The design demonstration allows the IGC Code to require only a partial secondary barrier (capable of holding leakage for about 15 days, designed to a specific drip-tray capacity rather than a full secondary tank).

The two principal Type B implementations are:

• Moss spherical tank (Norwegian-designed, Kvaerner / Moss Maritime), used in many older LNG carriers (the recognisable spherical hump silhouette). The sphere geometry is highly efficient stress-wise; aluminium alloy 5083 is the standard material. The spherical tanks are insulated and supported on a single equatorial skirt.
• IHI Self-Supporting Prismatic Type B (IHI SPB), used in some Japanese LNG carriers. The tank is a prismatic shape (more space-efficient than a sphere) but the design demonstration meets the Type B leak-before-break criteria. 9% nickel steel construction.

Independent Type C tanks

Type C independent tanks are pressure vessels designed to ASME Boiler and Pressure Vessel Code Section VIII or equivalent national pressure-vessel standards. They operate at significant gauge pressure (typically 5-20 bar for LPG service) and are exempt from the secondary barrier requirement (the pressure-vessel design demonstrates intrinsic robustness).

Type C tanks are the dominant containment for LPG carriers (fully pressurised, semi-refrigerated, and fully refrigerated grades) and increasingly common for ammonia carriers. They are also used in small-scale LNG carriers for bunkering and short-sea trade where the cargo capacity is small enough that the pressure-vessel approach is economical.

The pressure-vessel cylindrical or bilobe geometry is space-inefficient compared to prismatic tanks, but the elimination of the secondary barrier and the reduced inerting requirements offset some of that disadvantage. Type C tanks are typical at smaller cargo capacities (<30,000 m³ total).

Membrane tanks

Membrane tanks are integrated with the inner hull: a thin (typically 0.7-1.2 mm) primary metal membrane is fixed to a layer of insulation that is in turn fixed to the inner hull plating. The hull provides the structural strength; the membrane provides the cryogenic-tight surface in contact with the cargo. The membrane itself is Invar (36% nickel iron alloy) for LNG service (NO96 system) or stainless steel in corrugated form (Mark III system).

The two dominant membrane systems both come from Gaztransport & Technigaz (GTT) of France:

• GTT Mark III, corrugated stainless steel primary membrane, foam insulation, secondary membrane of triplex (laminated material). Most modern LNG carriers use Mark III or Mark III Flex.
• GTT NO96, Invar primary and secondary membranes, plywood-supported insulation. Older but still in production.

Membrane systems are space-efficient (the cargo fills more of the ship’s beam-and-depth envelope than spherical tanks) and have driven the cargo capacity of modern LNG carriers from ~125,000 m³ (older Moss-design) to 175,000-180,000 m³ (Q-Flex and Q-Max generations of membrane vessels).

Containment-system choice in practice

For LNG service, the modern industry essentially chooses between GTT Mark III/NO96 membrane (most common) and Moss spherical Type B (declining share, mostly older tonnage). For LPG service, Type C pressure vessels dominate. For ammonia service, Type C is most common but membrane systems are increasingly used for newer larger ammonia carriers. Both LNG cargo containment systems and LNG carrier articles cover containment selection in greater detail.

MARVS and pressure relief

Maximum Allowable Relief Valve Setting

The Maximum Allowable Relief Valve Setting (MARVS) is the central pressure-control parameter under the IGC Code (Chapter 8). MARVS is the highest pressure at which the cargo tank’s pressure-relief valve may discharge, it represents the design ceiling for the tank’s normal operating pressure.

MARVS depends on the containment-system type:

• Type A: MARVS typically 0.25 bar gauge (very close to atmospheric, Type A tanks are atmospheric-pressure tanks)
• Type B: MARVS typically 0.25 bar gauge (similar to Type A)
• Type C: MARVS depends on the pressure-vessel design pressure; typically 5-20 bar gauge for LPG service
• Membrane: MARVS typically 0.25-0.7 bar gauge

The IGC Code requires two independent pressure-relief means, each rated for full relief flow at MARVS, with discharges piped to a safe location (the vent mast at the top of the cargo system). The MARVS Safety Margin (IGC 8.2) calculator implements the IGC Chapter 8.2 check.

Vacuum relief

In addition to overpressure relief, IGC requires vacuum-relief protection: tanks must not collapse from internal vacuum during cargo cooldown or discharge. Vacuum-relief valves (or vacuum-breaker arrangements) admit nitrogen or boil-off gas to maintain positive pressure during cooldown.

Operating pressure regime

In normal operation, an LNG cargo tank holds pressure substantially below MARVS (typically 0.05-0.15 bar gauge), with the boil-off gas (BOG) being continuously removed and either reliquefied, used as fuel in dual-fuel engines, or burned in the gas combustion unit (GCU). The pressure-relief valve provides the last-resort protection against any failure of the BOG management system.

Materials of construction

Cryogenic steel grades for LNG service

LNG cargo tanks operate at approximately -163°C (the boiling point of methane at atmospheric pressure). Standard structural steel becomes brittle below about -50°C and cannot be used at LNG temperatures. The IGC Code specifies several approved materials:

• 9% nickel steel (5%-9% Ni grades, ASTM A553), used for LNG cargo tanks (Type A, Type B IHI SPB, some Type C). Resilience-tested at -196°C; widely available; weldable with appropriate procedures.
• Invar (36% nickel iron alloy), used for GTT NO96 membrane systems. Near-zero coefficient of thermal expansion at LNG temperatures, eliminating the need for expansion joints.
• Aluminium alloy 5083, used for Moss spherical tanks. Cryogenic-rated; low density advantageous for the spherical geometry’s structural support requirements.
• Austenitic stainless steel (304L, 304LN), used for GTT Mark III primary membrane. Cryogenic-rated, easily corrugated for thermal-expansion accommodation.

Materials for LPG service

LPG cargo tanks operate at much higher temperatures than LNG (the boiling points of propane and butane are -42°C and -0.5°C respectively). Material selection is therefore less demanding:

• Standard structural steel grades (with appropriate impact testing) are acceptable for many LPG service temperatures.
• Lower-nickel steels (3.5% Ni) are common for fully-refrigerated LPG operation around -42°C.
• Carbon steel pressure-vessel grades are standard for fully-pressurised and semi-refrigerated LPG Type C tanks.

Materials for ammonia service

Ammonia (boiling point -33°C) is corrosive to copper, copper alloys, brass and zinc, these materials must not be used in any wetted-surface application in an ammonia carrier. The IGC Code Chapter 19 entry for ammonia explicitly prohibits these materials. Otherwise, ammonia-grade carbon steel (with attention to stress-corrosion cracking) is the standard material.

Cargo handling and gas management

Cooldown

Before the first cargo loading, a warm cargo tank must be cooled down to cargo temperature gradually to avoid thermal shock. The cooldown procedure for LNG involves:

1. Inerting the tank with nitrogen to oxygen below 5%.
2. Introducing a controlled flow of LNG through cooldown spray nozzles at the tank top.
3. Spraying liquid LNG which evaporates immediately on contact with the warm tank surfaces, removing heat and gradually cooling the structure.
4. Continuous monitoring of tank temperature gradients to ensure uniform cooldown (avoiding thermal stress concentration).
5. Continued cooldown until the tank reaches near-cargo temperature (around -160°C for LNG), at which point bulk loading can begin.

Cooldown of a large LNG cargo tank from ambient (+30°C) to cargo temperature takes typically 24-48 hours. The LNG Tank Cool-Down Time calculator implements the cooldown-time estimation based on heat capacity and spray rate.

Boil-off gas management

In normal LNG operation, the cargo continuously evaporates due to heat ingress through the insulation. The boil-off rate (BOR) is typically 0.10-0.15% of cargo per day for modern LNG carriers, depending on insulation quality, ambient temperature, and cargo level. The LNG Boil-Off Rate from Heat Ingress calculator implements the BOR estimation.

The boil-off gas (BOG) must be removed continuously to prevent tank pressure from rising above MARVS. The Code requires at least one BOG management option, with several options commonly combined:

• Use as fuel in dual-fuel engines (the dominant modern approach since the 2000s, turning the boil-off into propulsion energy rather than waste).
• Reliquefaction via on-board reliquefaction plant, common for LPG carriers, less common for LNG.
• Combustion in a Gas Combustion Unit (GCU), a backup that thermally oxidises BOG to CO₂ and water vapour without recovering the energy. The LNG GCU Required Capacity calculator implements the sizing logic.

The LNG BOG Compressor Shaft Power calculator supports BOG compressor sizing for fuel-gas-supply applications.

Reliquefaction

LPG carriers typically include on-board reliquefaction plant: a refrigeration cycle that condenses the BOG back to liquid and returns it to the cargo tank. Reliquefaction is more common on LPG than LNG because the LPG temperatures are less extreme (refrigeration cycles operate at -42°C rather than -163°C, requiring less energy and less complex equipment). The LPG Reliquefaction COP calculator implements the coefficient-of-performance estimation.

Heel for return voyage

LNG carriers typically retain a small quantity of LNG (the heel) on the return ballast voyage, both to keep the cargo tanks cold (avoiding the long cooldown time at the next loading port) and to provide BOG fuel for the propulsion. The LNG Heel for Return Voyage calculator implements the heel-volume estimation based on voyage length, BOR, and propulsion fuel demand.

Gas freeing and inerting

When a gas carrier needs to enter dry-dock for repairs or to change cargo grade, the cargo tank must be gas-freed: progressively replaced with first inert gas (nitrogen or carbon dioxide), then air, until the tank atmosphere is breathable. The IGC Code requires a documented procedure with continuous gas-monitoring at multiple sample points.

The reverse process (inerting before bringing the tank back into cargo service) replaces air with nitrogen (or nitrogen-enriched atmosphere) and then with cargo vapour, ensuring no air remains in contact with the cargo. The LNG Tank Inerting Dilution Purge Volume calculator and the LNG Tank Displacement Purge Volume calculator implement the purge-volume calculations.

Process safety architecture

Cargo area segregation

The IGC Code requires strict separation of the cargo area (containing all cargo tanks, cargo handling equipment, and gas-tight piping) from the machinery space, accommodation, and service spaces. The boundaries between these areas must be gas-tight (Class A-60 fire bulkheads, vapour-tight closures on doors and ventilation openings).

The IGC Code further requires cofferdams between cargo tanks and adjacent machinery spaces (typically with heated cofferdam atmosphere to prevent condensation against the cold cargo tank) and limits crossings of the cargo-area boundary to specifically engineered cargo-area-to-machinery-space penetrations (cargo and BOG piping with specific double-isolation arrangements).

The Cofferdam Heating calculator implements the heating duty and surface-temperature estimation for cargo cofferdams.

Leak detection

The IGC Code requires gas detection at multiple locations within the cargo system: ullage spaces, machinery and pump spaces in the cargo area, vent mast outlets, accommodation block air intakes, and machinery space air intakes. Detection is typically by infrared or catalytic-bead sensors with continuous read-out at the cargo control room. Alarm thresholds are typically set at 30% of the lower flammable limit (LFL) for hydrocarbons or at the immediately-dangerous-to-life-and-health (IDLH) threshold for toxic cargoes.

Emergency shutdown (ESD)

The IGC Code requires a two-stage emergency shutdown system: ESD-1 (initial isolation of cargo flow at the manifold) and ESD-2 (immediate stop of all cargo pumps and full closure of all valves). ESD activation must occur:

• Automatically on detection of cargo leakage above threshold
• Automatically on high-high level alarm in any cargo tank
• Manually from any of multiple emergency stations distributed throughout the vessel
• Automatically on loss of cargo control room power

Modern ESD systems are interfaced with shore terminal ESD systems via the ship-shore link (typically a fibre-optic ESD cable connected at the manifold) so that an ESD initiated on either side immediately propagates to the other.

High-high level alarm

Each cargo tank has an independent high-high level alarm that automatically initiates ESD if the cargo level reaches the maximum allowable filling limit (typically 98.5-99% of the tank’s certified liquid volume). The alarm must be independent of the routine level-gauging system to ensure that a gauging-system failure does not defeat the protection.

Survey and certification

Certificate of Fitness

The defining regulatory output of IGC compliance is the Certificate of Fitness for the Carriage of Liquefied Gases in Bulk. The certificate is issued by the flag state (or by a recognised classification society on behalf of the flag state) following a comprehensive survey of the ship and its operational systems. It lists:

• The vessel’s IGC ship type (1G, 2G, 2PG, or 3G)
• The cargo types approved for carriage (with reference to IGC Chapter 19 entries)
• Any operational restrictions (loading-port, discharge-port, voyage-region)
• The expiration date

The Certificate of Fitness is valid for a maximum of 5 years, with intermediate, annual, and renewal surveys at the standard SOLAS frequencies. A vessel without a current Certificate of Fitness cannot legally carry IGC cargoes.

Survey regime

The IGC Code specifies survey requirements at four frequencies:

• Initial survey before the certificate is first issued, comprehensive verification that the ship complies with every IGC Chapter requirement.
• Renewal survey at 5-year intervals, same scope as initial.
• Intermediate survey between the second and third anniversary dates, focused on cargo-system integrity and safety equipment.
• Annual survey, verification that no major changes have occurred and that operational records are in order.

Class society inspectors (ABS, BV, ClassNK, DNV, KR, LR, RINA) conduct most surveys; flag states verify the class survey output for certification.

Training requirements

STCW V/1-2

The STCW Convention Section A-V/1-2 sets the training requirements for officers and ratings on liquefied gas tankers:

• Basic Liquefied Gas Tanker Familiarisation (STCW A-V/1-2-1), a one-week course required for all crew with cargo-related duties.
• Advanced Liquefied Gas Tanker Training (STCW A-V/1-2-2), a two-week course required for masters, chief engineers, chief officers, and deck officers in charge of cargo operations.
• Tanker familiarisation (STCW A-V/1-1-1), a more general course required for all officers on any tanker, including gas tankers.

Vessels are required to maintain training records demonstrating that all personnel hold the appropriate certifications. Port-state and flag-state inspections regularly check these records.

Operational training

In addition to STCW certifications, gas-carrier crew typically complete:

• Vessel-specific familiarisation, typically 2-4 weeks on first joining a new ship-type or first joining a specific vessel
• Annual emergency drills including ESD activation, fire-fighting in the cargo area, mass-spill response
• Pre-cargo-operation briefings for every cargo loading and discharge

Recent IGC Code amendments and emerging cargoes

Amendments since 2016

Since the 2016 entry into force of the rewritten Code, several amendments have been adopted:

• Resolution MSC.411(97), minor clarifications to Chapter 19 cargo entries (entered into force 2018).
• Resolution MSC.475(101), addition of new cargo entries reflecting trade developments (entered into force 2021).

Ammonia and methanol

The growing interest in ammonia as a marine fuel and as a low-carbon energy carrier has driven additional IGC Code attention to ammonia carriage. Ammonia has been an IGC cargo since the original 1986 Code, but the post-2020 ammonia-economy outlook has prompted IMO to revisit several Chapter 19 entries to clarify carriage of large-tonnage ammonia. The same trend has prompted updates for methanol (which is not an IGC Code cargo (methanol is an IBC Code chemical at ambient temperature) but the IGF Code addresses methanol as fuel).

CO₂ as cargo

Liquid CO₂ carriage for carbon capture and storage (CCS) projects has driven new IGC Code entries. Liquid CO₂ is shipped at moderate pressure (around 7-15 bar) and around -50°C, making Type C pressure vessels the natural containment. A new generation of dedicated CO₂ carriers is in early-stage construction.

Notable casualties

El Paso Sonatrach 1971

The early gas-carrier era saw several fires and explosions during cargo operations. The El Paso Sonatrach fire in 1971 (Boston Harbor) is one of the better-documented early LNG cargo casualties; it drove early development of the cargo-area segregation and inerting requirements that ultimately appeared in the GC and IGC Codes.

Yuyo Maru 10 1974

The Yuyo Maru 10 collision in Tokyo Bay in November 1974 (a fully-laden LPG carrier struck by a freighter) produced a severe fire and substantial loss of life. The casualty drove early IGC requirements on cargo-area damage stability and the inboard tank-position requirements.

Rocknes 2004

The Rocknes capsizing in 2004 was not a gas-carrier specific casualty (the vessel was a self-discharging bulk carrier) but the loss of ship and crew highlighted the importance of damage-stability margins in gas-carrier and bulk-carrier design.

The relatively short list of major IGC-era casualties reflects the success of the Code’s prescriptive framework: serious gas-carrier incidents are rare compared to the operational tonnage. The Code’s emphasis on multiple barriers (containment system + secondary barrier + segregation + ESD + leak detection) has produced an industry safety record substantially better than tanker industry averages.

See also

• LNG Cargo Containment Systems
• LNG Carrier
• LNG as Marine Fuel
• LNG Fuel System
• SOLAS Chapter VII Carriage of Dangerous Goods
• STCW Convention
• IBC Code (sister regulation for chemical tankers at ambient temperature)
• Marine Inert Gas Systems
• Marine Cargo Tank Heating Systems
• IMDG Class 2 Gases

References

• International Maritime Organization. International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code), 2016 edition (consolidating the 2014 rewrite). Chapters 1 (general), 2 (ship survival capability), 3 (ship arrangements), 4 (cargo containment), 5 (process pressure vessels and liquid, vapour, and pressure piping systems), 6 (materials of construction and quality control), 7 (cargo pressure / temperature control), 8 (vent systems for cargo containment), 9 (cargo containment system atmosphere control), 10 (electrical installations), 11 (fire protection and extinction), 12 (artificial ventilation in the cargo area), 13 (instrumentation and automation systems), 14 (personnel protection), 15 (filling limits for cargo tanks), 16 (use of cargo as fuel), 17 (special requirements), 18 (operating requirements), 19 (summary of minimum requirements per cargo).
• IMO Resolution MSC.370(93) adopting the rewritten IGC Code (May 2014, in force 1 January 2016).
• IMO Resolution MSC.5(48) adopting the original IGC Code (1983, in force 1 July 1986).
• IMO Resolution MSC.391(95) adopting the IGF Code (June 2015, in force 1 January 2017).
• International Convention for the Safety of Life at Sea, 1974 (SOLAS), Chapter VII Part C Construction and Equipment of Ships Carrying Liquefied Gases in Bulk; Chapter II-2 Fire protection.
• International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW), Section A-V/1-2 Liquefied Gas Tanker Training.
• IACS Unified Requirements UR W1 (welding criteria), UR W11 (steel grade selection), UR S26 (cargo tank steel and structure), and class society rules for gas carriers (ABS Rules for Building and Classing Gas Carriers; DNV Rules for Classification (Gas Carriers; LR Rules and Regulations for the Classification of Ships) Gas Tankers; Bureau Veritas Rules for the Classification of Steel Ships, Liquefied Gas Carriers; ClassNK Rules for the Survey and Construction of Steel Ships, gas tanker provisions).
• ASME Boiler and Pressure Vessel Code, Section VIII, pressure-vessel design code referenced for Type C tanks.
• Gaztransport & Technigaz (GTT), technical specifications for the Mark III, Mark III Flex, NO96, and NO96 Max membrane systems.
• SIGTTO Liquefied Gas Handling Principles on Ships and in Terminals (5th edition), the industry reference for gas-carrier operation.
• OCIMF and SIGTTO joint guidelines on Ship/Shore Interface for LNG Operations.
• WS Atkins / DNV / LR published research on Type B leak-before-break demonstrations.
• Marine Accident Investigation Branch (UK) and counterpart national investigation reports for cited casualties.