Gas carrier

[1] The seaborne transport of liquefied gases began in 1934 when a major international company put two combined oil/LPG tankers into operation.

[2] The ships, basically oil tankers, had been converted by fitting small, riveted, pressure vessels for the carriage of LPG into cargo tank spaces.

This enabled transport over long distances of substantial volumes of an oil refinery by-product that had distinct advantages as a domestic and commercial fuel.

LPG is not only odourless and non-toxic, it also has a high calorific value and a low sulphur content, making it very clean and efficient when being burnt.

Today, most fully pressurised oceangoing LPG carriers are fitted with two or three horizontal, cylindrical or spherical cargo tanks and have typical capacities between 20,000 and 90,000 cubic meters and Length overall ranging from 140 m to 229 m .

[3] Fully pressurized ships are still being built in numbers and represent a cost-effective, simple way of moving LPG to and from smaller gas terminals.

Semi-pressurized/semi-refrigerated carriers incorporate cylindrical, spherical or bi-lobe shaped tanks carrying propane at a pressure of 8.5 kg/cm2 (121 psi), and a temperature of −10 °C (14 °F).

They are built to carry liquefied gases at low temperature and atmospheric pressure between terminals equipped with fully refrigerated storage tanks.

Prismatic tanks enabled the ship's cargo carrying capacity to be maximised, thus making fully refrigerated ships highly suitable for carrying large volumes of cargo such as LPG, ammonia and vinyl chloride over long distances.

The main type of cargo containment system utilised on board modern fully refrigerated ships are independent tanks with rigid foam insulation.

[7] CNG carrier technology relies on high pressure, typically over 250 bar (2900 psi), to increase the density of the gas and maximize the possible commercial payload.

[10] The IGCCode which applies to new gas carriers (built after 30 June 1986) is the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk.

The IGC Code, under amendments to International Convention for the Safety of Life at Sea (SOLAS), is mandatory for all new ships.

As proof that a ship complies with the Code, an International Certificate of Fitness for the Carriage of Liquefied Gases in Bulk should be on board.

Accordingly, most charterers will expect such ships to meet with Code standards and, as proof of this, to have on board a Certificate of Fitness for the Carriage of Liquefied Gases in Bulk.

Accordingly, many ships of this age are required by charterers to meet with Code standards and to have on board a Certificate of Fitness for the Carriage of Liquefied Gases in Bulk.

Type B Independent Tanks are generally spherical and welded to a vertical cylindrical skirt, which is the lone connection to the ship's main hull.

Lobe-type tanks are commonly used at the forward end of the ship, to improve the poor utilization of the hull volume.

Vinyl chloride commonly carried on gas carriers is a known as a human carcinogen, particularly liver cancer.

Caution must be exerted while dealing with such cargoes, precautions such as use of Chemical suits Self-contained Breathing Apparatus (SCBA's) and gas tight goggles must be worn at all times to prevent exposure.

Flameless explosions which result out of cold cargo liquid coming into sudden contact with water do not release much energy.

The cargoes are carried at extremely low temperatures, from 0 to −163 °C (32 to −261 °F), and hence frostbite due to exposure of skin to the cold vapours or liquid is a very real hazard.

Anhydrous ammonia is a hygroscopic compound, this means it will seek moisture source that may be the body of the operator, which is composed of 90 percent water.

When a human body is exposed to anhydrous ammonia the chemical freeze burns its way into the skin, eyes or lungs.

Most deaths from anhydrous ammonia are caused by severe damage to the throat and lungs from a direct blast to the face.

At first, the skin will become red (but turn subsequently white); the affected area is painless, but hard to touch, if left untreated the flesh will die and may become gangrenous.