IGC CODE CONSTRUCTION OF SHIPS CARRYING BULK GASES LIQUEFIED HYDROGEN NATURAL GAS METHANE IMO INTERNATIONAL CLASSIFICATION CERTIFICATION SHIPS CARGO VESSELS TANKERS

The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code), adopted by resolution MSC.5(48), has been mandatory under SOLAS chapter VII since 1 July 1986. The IGC Code applies to ships regardless of their size, including those of less than 500 gross tonnage, engaged in carriage of liquefied gases having a vapour pressure exceeding 2.8 bar absolute at a temperature of 37.8°C, and certain other substances listed in chapter 19 of the Code.

The Code does not apply to ships carrying liquefied hydrogen, that are not engaged in commercial carrying.

The aim of the Code is to provide an international standard for the safe carriage by sea in bulk of liquefied gases and the substances listed in chapter 19, by prescribing the design and construction standards of ships involved in such carriage and the equipment they should carry so as to minimize the risk to the ship, to its crew and to the environment, having regard to the nature of the products involved.

Classification evolves slowly as a trailing edge to innovation and technological advancement. Climate change and air pollution is now pushing the barriers at a pace that is uncomfortable for the IMO and certifying societies, with the IMO re-writing the rules as Approvals in Principle are given to hydrogen vessels, following in the wake of cryogenic LNG, that never quite got a hold on the market, before it was time to up the MARPOL game, to combat anthropogenic warming of the planet.

The basic philosophy is one of ship types related to the hazards of the products covered by these codes, each of which may have one or more hazard properties. A further possible hazard may arise owing to the products being transported under cryogenic (refrigerated) or pressure conditions.

Severe collisions or strandings could lead to cargo tank damage and uncontrolled release of the product. Such release could result in evaporation and dispersion of the product and, in some cases, could cause brittle fracture of the ship's hull. The requirements in the codes are intended to minimize these risks as far as is practicable, based upon present knowledge and technology.

Throughout the development of the Code it was recognized that it must be based upon sound naval architectural and engineering principles and the best understanding available as to the hazards of the various products covered; furthermore that gas carrier design technology is not only a complex technology but is rapidly evolving and that the Code should not remain static. Therefore, IGC Code is kept under review, taking into account experience and technological development. The latest comprehensive amendments of the IGC Code were adopted by resolution MSC.370(93), expected to enter into force on 1 July 2016.

-	HYDROGEN	METHANE	REFERENCES
-	-	-	-
Boiling temperature (K)*	20.3	111.6	ISO1), Annex A, Table A.3
Liquid density (kg/m3)*	70.8	422.5	ISO1), Annex A, Table A.3
Gas density (kg/m3)** (Air: 1.198)	0.084	0.668	NIST RefProp 10)
Viscosity (g/cm•s x 10-6) Gas Liquid	8.8 13.49	10.91 116.79	NIST RefProp 10) NIST RefProp 10)
Flame temperature in air (°C)	2396	2230	Calculated using Cantera and GRI 3.0 mechanism
Maximum burning velocity (m/s)	3.15	0.385	Calculated using Cantera and GRI 3.0 mechanism
Heat of vapourization (J/g)*	448.7	510.4	ISO 1), Annex A, Table A.3
Lower flammability limit (% vol. fraction)***	4.0	5.3	ISO 1), Annex A, Table B.2
Upper flammability limit (% vol. fraction)***	75.0	17.0	ISO 1), Annex A, Table B.2
Lower detonation limit (%vol. fraction)***	18.3	6.3	ISO 1), Annex A, Table B.2
Upper detonation limit (% vol. fraction) ***	59.0	13.5	ISO 1), Annex A, Table B.2
Minimum ignition energy (mJ)***	0.017	0.274	ISO 1), Annex A, Table B.2
Auto-ignition temp. (°C)***	585	537	ISO 1), Annex A, Table B.2
Toxicity	Non	Non	Orange book 5)
Temperature at critical point (K)	33.19****	190.55	Hydrogen: ISO 1), Annex A, Table A.1 Methane: The Japan Society of Mechanical Engineers, Data Book, Thermophysical Properties of Fluids (1983)
Pressure at critical point (kPaA)	1297****	4595	Hydrogen: ISO 1), Annex A, Table A.1 Methane: The Japan Society of Mechanical Engineers, Data Book, Thermophysical Properties of Fluids (1983)

*** Ignition and combustion properties for air mixtures at 25°C and 101.3 kPaA.

STANDARD ISO - 20m3 cryogenic tanks, multi-layered vacuum insulation, in stainless steel. Large tanks are available from many manufacturers concerning LNG.