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Origin, Applicability, Requirement of IMO Gas Code

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The Origin Gas Code outlines the standards and regulations governing the safe transportation and handling of liquefied natural gas (LNG) from its point of origin to its destination. This code specifies procedures, protocols, and safety measures to ensure the integrity and security of LNG shipments throughout the supply chain. It covers aspects such as vessel design, construction, equipment, operational procedures, and emergency response protocols, aiming to mitigate risks and prevent accidents associated with LNG transportation.The applicability of the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) extends to vessels engaged in the transportation of liquefied gases, including LNG carriers.

This Code, adopted by the International Maritime Organization (IMO), sets forth comprehensive standards for the design, construction, and operation of gas carriers to ensure their safety and environmental protection. It mandates requirements related to vessel stability, cargo containment systems, fire protection, ventilation, and crew training, among others. Compliance with the IGC Code is mandatory for LNG carriers and other gas-carrying vessels to obtain certification and operate legally, promoting uniformity and consistency in safety standards across the maritime industry.

The Origin of the Gas Code

Since the inception of liquefied gas carriers into the shipping field, it was recognized that there was a need for an International Code for the carriage of liquefied gases in bulk.

At the beginning of the 1970’s The Marine Safety Committee (MSC) of the International Maritime Organization (IMO), known then as the International Maritime Consultative Organization (IMCO), started work on a Gas Carrier Code with the participation of the major country delegations representing Gas Carrier owners, the International Association of Classification Societies, the United States Coast Guard and several other International associations.

The result of this work was the “Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk” introduced under Assembly Resolution A328 (IX) in November 1975.

This was the first code developed by IMO having direct applicability to Gas Carriers. The intention was to provide “a standard for the safe bulk carriage of liquefied gases (and certain other substances) by sea by prescribing design and constructional features of ships and their equipment, so as to Safety, Risks and Security Aspects in Liquefied Natural Gas Industryminimize risks to ships, their crew and the environment“.

The IGC Code has been adopted by most countries interested by the transport of liquefied gases by sea as well as all Classification Societies and is now part of SOLAS.

Applicability of the IGC Code

The applicability of the code is as follows:


The Code, which applies to new gas carriers (built after June 1986) is the “International Code for the Construction and Equipment of Ships carrying Liquefied Gases in Bulk” known as the IGC code.

At a meeting of the MSC in 1983 approving the second set of amendments to SOLAS the requirements of the IGC Code become mandatory with almost immediate effect.


The regulations covering gas carriers built after 1976 but before 1st July 1986 is the “Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk” known as the Gas Carrier Code or GC Code and adopted under Assembly resolution A328 (IX).

Since 1975 the MSC has approved four sets of amendments to the GC Code, the latest in June 1993.


The regulations covering gas carriers built before 1977 are contained in the “Code for Existing Ships Carrying Liquefied Gases in Bulk” first advertised under Assembly Resolution A 329 (IX). Its content is similar to the IGC code, though less extensive. The Existing Ship Code was completed in 1976 and remains as an IMO Recommendation for all gas carriers in this fleet of ships.

IGC Code Requirement, which are not within the Scope of the Class Certification

Most of the provisions in the IMO Code are covered by the ABS rules and regulations, however attention must be drawn to the fact that it contains requirements that are not within the scope of classification as defined in the Rules. In particular, the requirements contained in the following chapters and paragraphs of the IGC Code are not within the scope of classification:

  • Chapter I, Section 1.4 – Equivalents.
  • Chapter I, Section 1.5 – Surveys and certification.
  • Chapter II Ship Survival Capability.
  • Chapter XIV Personnel Protection.
  • Chapter XVIII – Operating requirements.

However, also these requirements are to be applied by ABS when acting on behalf of the flag Administration, within the scope of its delegation.

The Certificate of Fitness

The IGC Code requires that a Certificate (International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk) be issued to all new gas carriers. The certificate should comply with a pro-forma, as set out in “Model Form” attached as an Appendix to the Code and should be available on board all new gas carriers.

The purpose of this certificate is to confirm compliance with the IMO:


As ABS has incorporated into its Rules this Code, compliance with ABS Rules automatically assures the compliance with the Gas Code, with the exception of the few operative requirements, therein contained, which are not subject of classification. It is therefore very easy for ABS to issue this certificate, when authorized by the vessel flag Administration, or a Statement of Fact letter in case the vessel flag administration does not authorize ABS to act on their behalf.

The scheme of the surveys and the correspondent certificates are as follows:

  • INITIAL SURVEY – Issuance of the certificate.
  • MANDATORY ANNUAL SURVEY – Endorsement of the certificate.
  • INTERMEDIATE SURVEY – Endorsement of the certificate.
  • RENEWAL SURVEY – Extension of the certificate.

The responsibility for interpretation of the IGC Code requirements for the purpose of issuing an International Certificate of Fitness for Liquefied Gas Carrier Typesthe Carriage of Liquefied Gases in Bulk lies with the Administration of the state whose flag the ship is entitled to fly.

Whenever ABS is authorized by an Administration to issue on its behalf the “Certificate of Fitness for the Carriage of Liquefied Gases in Bulk“, or where the ABS is authorized to carry out plan review and surveys on behalf of an Administration on the basis of which the “Certificate of Fitness for the Carriage of Liquefied Gases in Bulk” will be issued by the Administration, or where ABS is requested to certify compliance with the IGC Code without issuing a formal Statement of Fact, the full compliance with the requirements of the IGC Code, including the operative requirements therein contained, is to be granted by ABS.

Products Covered in the IGC Code

The Code applies to ships regardless of their size, including those of less than 500 tons gross tonnage, engaged in the carriage of liquefied gases having a vapor pressure exceeding 2,8 bar absolute at a temperature of 37,8 °C, and other products as shown in chapter XIX, when carried in bulk. Table below lists all products contemplated in Chapter XIX of the Code.

Products covered in the IGC
ProductIMO NumberProductIMO Number
Ammonia, anhydrous1005Methane (LNG)1972
Butadiene1010Methyl acetylene – propadiene1060
Butane1011Methyl bromide1062
Butane – propane mixture1011/1978Methyl chloride1063
Diethyl ether1155Propane1978
Ethane1961Propylene oxide1280
Ethyl chloride1037Refrigerant gases
Ethylene1038Sulphur dioxide1079
Ethylene oxide1040Vinyl chloride1086
Ethylene oxide-propylene oxide mixture with ethylene oxide content of not more than 30 % by weight2983Vinyl ethyl ether1302
Isoprene1218Vinylidene chloride1303

Topics Dealt with in the IGC Code

The IGC contains 19 chapters, which deal with technical requirements in the following categories:

  • Issuance of the Certificate of Fitness (Chapter I – “General“).
  • Freeboard and intact stability (Chapter II – “Ship survival capability and location of cargo tanks“).
  • Conditions of loading (Chapter II – “Ship survival capability and location of cargo tanks“).
  • Damage assumptions (Chapter II – “Ship survival capability and location of cargo tanks“).
  • Survivability (Chapter II – “Ship survival capability and location of cargo tanks“).
  • Segregation of cargo area (Chapter II – “Ship arrangements“).
  • Vessel arrangement: location of cargo tanks, combinations, service and machinery spaces, control stations and the cargo pump room (Chapter III – “Ship arrangements“).
  • Bilge, ballast and fuel oil arrangements (Chapter III – “Ship arrangements“).
  • Loading and unloading arrangement (Chapter III – “Ship arrangements“).
  • Design and fabrication of cargo containment system including design loads, required analyses, allowable stresses, secondary barriers, materials of construction, nondestructive examination and testing (Chapter IV – “Cargo containment“).
  • Process pressure vessels (Chapter V – “Process pressure vessels and liquid, vapour and pressure systems“).
  • Liquid and vapor cargo piping systems (Chapter V – “Process pressure vessels and liquid, vapour and pressure systems“).
  • Materials for cargo containment system (Chapter VI – “Materials of construction“).
  • Materials for cargo piping systems (Chapter VIMaterials of construction“).
  • Welding and NDT (Chapter VI – “Materials of construction“).
  • Cargo and pressure control (Chapter VII – “Cargo pressure / temperature control“).
  • Refrigeration and reliquefaction systems (Chapter VII – “Cargo pressure / temperature control“).
  • Over-pressure and under-pressure protection for the cargo containment system (Chapter VIII – “cargo tank vent systems“).
  • Gas freeing and inerting (Chapter IX – “Environmental control“).
  • Electrical equipment and electrical plants (Chapter X – “Electrical installations“).
  • Fire safety (Chapter XI – “Fire protection and fire extinction“).
  • Fire extinguishing systems and firemen’ outfit (Chapter 11 – “Fire protection and fire extinction“).
  • Ventilation of cargo spaces (Chapter XII – “Mechanical ventilation in the cargo area“).
  • Cargo control system and instrumentation of the cargo block (Chapter XIII – “Instrumentation (gauging – gas detection)”).
  • Protective and safety equipment (Chapter XIV – “Personnel protection“).
  • Cargo filling limits (Chapter XV – “Filling limits for cargo tanks“).
  • Use of cargo as fuel in steam plants (Chapter XVI – “Use of cargo as fuel“).
  • Use of cargo as fuel on diesel engines and gas turbines (Chapter XVI – “Use of cargo as fuel“).
  • Special requirements for specific products (Chapter XVII – “Special requirements“).
  • Operating requirements (Chapter XVIII – “Operating requirements“).
  • Summary of specific requirements on ships characteristics related to each type of cargo (Chapter XIX – “Summary of minimum requirements“).


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Апрель, 03, 2024 150 0
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