
A gas carrier, gas tanker, LPG carrier, or LPG tanker is a ship designed to transport
LPG,
LNG
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
,
CNG
Compressed natural gas (CNG) is a fuel gas mainly composed of methane (CH4), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of , usually in c ...
, or liquefied chemical gases in
bulk. Gases are kept refrigerated onboard the ships to enable safe carriage in liquid and vapour form and for this reason, gas carriers usually have onboard refrigeration systems.
Design and construction of all gas carriers operating internationally is regulated by the
International Maritime Organization
The International Maritime Organization (IMO; ; ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for regulating maritime transport. The IMO was established following agreement at a ...
through the
.
There are various types of gas carriers, depending on the type of gas carried and the type of containment system, two of the most common being the Moss Type B (spherical) type and the membrane (typically GTT) type.
Types
Fully pressurized gas carrier

The seaborne transport of liquefied gases began in 1934 when a major international company put two combined oil/LPG tankers into operation. 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
The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it.
The ''calorific value'' is the total energy release ...
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 . New LPG Carrier ships are designed for dual-fuel propulsion system possessing the ability to utilize LPG or diesel fuel on a selective basis. 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-pressurised ships
These ships carried gases in a semi-pressurized/semi-refrigerated state. This approach provides flexibility, as these carriers are able to load or discharge at both refrigerated and pressurized storage facilities. Semi-pressurized/semi-refrigerated carriers incorporate cylindrical, spherical or bi-lobe shaped tanks carrying propane at a pressure of , and a temperature of .
Ethylene and gas/chemical carriers
LEG carriers are the most sophisticated of the gas tankers and have the ability to carry not only most other liquefied gas cargoes but also
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
at its atmospheric boiling point of . These ships feature cylindrical, insulated, stainless steel cargo tanks able to accommodate cargoes up to a maximum specific gravity of 1.8 at temperatures ranging from a minimum of −104 °C to a maximum of and at a maximum tank pressure of 4 bar.
Fully refrigerated ships

They are built to carry liquefied gases at low temperature and atmospheric pressure between terminals equipped with fully refrigerated storage tanks. However, discharge through a booster pump and cargo heater makes it possible to discharge to pressurized tanks too. The first purpose-built, lpg tanker was the m/t Rasmus Tholstrup from a Swedish shipyard to a Danish design. 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. Today, fully refrigerated ships range in capacity from . LPG carriers in the size range are often referred to as VLGCs (Very Large Gas Carriers). Although LNG carriers are often larger in terms of cubic capacity, this term is normally only applied to fully refrigerated LPG carriers.
The main type of cargo containment system utilised on board modern fully refrigerated ships are independent tanks with rigid foam insulation. The insulation used is quite commonly polyurethane foam. Older ships can have independent tanks with loosely filled perlite insulation. In the past, there have been a few fully refrigerated ships built with semi-membrane or integral tanks and internal insulation tanks, but these systems have only maintained minimal interest. The large majority of such ships currently in service have been constructed by shipbuilders in Japan and Korea.
Liquefied natural gas carriers

The majority of LNG carriers are between in capacity. In the modern fleet of LNG carriers, there is an interesting exception concerning ship size. This is the introduction of several smaller ships of between having been built in 1994 and later to service the needs of importers of smaller volumes.
Compressed natural gas carriers
Compressed natural gas (CNG) carrier ships are designed for transportation of
natural gas
Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
under high pressure. 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. CNG carriers are economical for medium distance marine transport and rely on the adoption of suitable pressure vessels to store CNG during transport and on the use of suitable loading and unloading compressors to receive the CNG at the loading terminal and to deliver the CNG at the unloading terminal.
Builders
These vessels are designed to transport liquefied gas. Builders of Liquefied Gas Carriers are:
*
Daewoo Shipbuilding & Marine
*
Damen Shipyard
*
Hyundai Heavy Industries
HD Hyundai Heavy Industries Co., Ltd. (HHI; ) is the world's largest shipbuilding company and a major heavy equipment manufacturer. Its headquarters are in Ulsan, South Korea.
History
HHI was founded in 1972 by Chung Ju-yung as a division ...
*
Hyundai Mipo
*
Hyundai Samho Heavy Industries
HD Hyundai Samho () is the world's largest dockyard and produces approximately 40 vessels per year. Its yard is located in Samho-eup, Yeongam, South Korea.
History
The company was first established with a name of Incheon Shipbuilding (인천� ...
*
Jiangnan
Jiangnan is a geographic area in China referring to lands immediately to the south of the lower reaches of the Yangtze River, including the southern part of its delta. The region encompasses the city of Shanghai, the southern part of Jiangsu ...
*
Kawasaki Shipbuilding Corporation
is the shipbuilding subsidiary of Kawasaki Heavy Industries. It produces primarily specialized commercial vessels, including LNG carriers, LPG carriers, container ships, bulk carriers, oil tankers, as well as high speed passenger jetfoils. In a ...
*
Mitsubishi Heavy Industries
is a Japanese Multinational corporation, multinational engineering, electrical equipment and electronics corporation headquartered in Tokyo, Japan. MHI is one of the core companies of the Mitsubishi Group and its automobile division is the prede ...
*
Imabari Shipbuilding
is a major Japanese ship building, marine engineering, and service company headquartered in Imabari, Ehime, Imabari, Ehime Prefecture, Japan.
It is Japan's largest shipbuilder both in terms of tonnage and sales revenue, with design, researc ...
*
Japan Marine United Corporation
South Korea, Japan and China are the main countries where LPG tankers are built, with small numbers built in the Netherlands and Bangladesh.
Cargoes carried on gas carriers
*
Butadiene
1,3-Butadiene () is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two ...
*
Ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
*
LPG
*
LNG
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
*
CNG
Compressed natural gas (CNG) is a fuel gas mainly composed of methane (CH4), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of , usually in c ...
*
Propylene
Propylene, also known as propene, is an unsaturated organic compound with the chemical formula . It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like o ...
*Chemical gases such as
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
,
vinyl chloride
Vinyl chloride is an organochloride with the formula H2C =CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. It is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). Vinyl chloride is a ...
,
ethylene oxide
Ethylene oxide is an organic compound with the chemical formula, formula . It is a cyclic ether and the simplest epoxide: a three-membered ring (chemistry), ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless ...
,
propylene oxide
Propylene oxide is an epoxide with the molecular formula C3H6O. This colourless volatile liquid with an odour similar to ether, is produced on a large scale industrially. Its major application is its use for the production of polyether polyols f ...
and
chlorine
Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
.
Gas carrier codes
The Gas Codes, developed by
International Maritime Organization
The International Maritime Organization (IMO; ; ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for regulating maritime transport. The IMO was established following agreement at a ...
apply to all gas carriers regardless of size. There are three Gas Codes and these are described below.
Gas carriers built after June 1986 (the
IGC Code
The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk, often referred and abbreviated as the IGC Code, is the International Maritime Organization (IMO) standard concerning the cargo carriage of liquefi ...
). 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. In brief, this Code is known as the IGC Code. The IGC Code, under amendments to
International Convention for the Safety of Life at Sea
The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty which sets out minimum safety standards in the construction, equipment and operation of merchant ships. The International Maritime Organiza ...
(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.
In 1993, the IGC Code was amended and the new rules came into effect on 1 July 1994. Ships on which construction started on or after 1 October 1994 should apply the amended version of the Code but ships built earlier may comply with previous editions of the IGC Code.
Gas carriers built between 1976 and 1986 (the GC Code)
The regulations covering gas carriers built after 1976 but before July 1986 are included in the Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk. It is known as the Gas Carrier Code or GC Code in short.
Since 1975,
International Maritime Organization
The International Maritime Organization (IMO; ; ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for regulating maritime transport. The IMO was established following agreement at a ...
(IMO) has approved four sets of amendments to the GC Code. The latest was adopted in June 1993. All amendments are not necessarily agreed by every government. Although this Code is not mandatory, many countries have implemented it into national law. 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.
Gas carriers built before 1977 (the Existing Ship Code)
The regulations covering gas carriers built before 1977 are contained in the Code for Existing Ships Carrying Liquefied Gases in Bulk. Its content is similar to the GC Code, though less extensive.
The Existing Ship Code was completed in 1976 after the GC Code had been written. It therefore summarises current shipbuilding practice at that time. It remains as an IMO recommendation for all gas carriers in this older fleet of ships. The Code is not mandatory but is applied by some countries for ship registration and in other countries as a necessary fulfilment prior to port entry. 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.
Cargo containment systems
For Gas carriers, including
LNG carrier
An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG).
Overview
The first oceangoing liquified natural gas tanker in the world was '' Methane Pioneer'', which entered service in 1959 with a carrying capacity of ...
s, gas design cargo containment systems are required.
These should include means to monitor temperature, volume and pressure, as well as pressure relief valves and associated safety systems in accordance with the
IGC Code
The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk, often referred and abbreviated as the IGC Code, is the International Maritime Organization (IMO) standard concerning the cargo carriage of liquefi ...
.
A cargo containment system is the total arrangement for containing cargo including, where fitted:
*A primary barrier (the cargo tank),
*Secondary barrier (if fitted),
*Associated
thermal insulation
Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...
,
*Any intervening spaces, and
*Adjacent structure, if necessary, for the support of these elements.
For cargoes carried at temperatures between the ship's hull may act as the secondary barrier and in such cases it may be a boundary of the hold space.
The basic cargo tank types utilised on board gas carriers are in accordance with the list below:
''Independent Type''
* Independent Type 'A'
Type A Independent Tanks are prismatic and supported on insulation-bearing blocks typically consisting of wooden chocks and located by anti-roll chocks located at the top of the tank inside the void space and anti-flotation chocks located inside the void space usually just above the double bottom tanks. The tanks are normally divided by a centreline liquid-tight bulkhead; by this feature, together with the chamfered upper
part of the tank, the free liquid surface effect is reduced and thus the virtual rise of the
Centre of gravity
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the barycenter or balance point) is the unique point at any given time where the weighted relative position of the distributed mass sums to zero. For a ...
and the stability is increased. When these cargo tanks are designed to carry LPG (at −50 °C), the tank is constructed of fine-grained low-carbon manganese steel or even stainless steel as seen in the
Maersk
(), usually known simply as Maersk ( ), is a Danish Freight transport, shipping and logistics company founded in 1904 by Arnold Peter Møller and his father Peter Mærsk Møller.
Maersk's business activities include Port operator, port operat ...
J class Ships. The hold space (void space) in this design is normally filled with dry inert gas or Nitrogen but may be ventilated with air during a ballast or gas free passage. The Conch design has been developed for carriage of
LNG
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
(at-163oC). The material for these cargo tanks has to be either 9% nickel steel or aluminium. The maximum allowable relief vapour setting (MARVS) is < 0. 7 bar.
* Independent Type 'B'
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. The hold space (void space) in this design is normally filled with dry inert gas or Nitrogen but may be ventilated with air during a ballast or gas free passage. A protective
steel
Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...
dome covers the primary barrier above deck level, and insulation encloses the outside of the primary barrier surface. This containment system has been used for carriage of
LNG
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
. The material of construction is either 9% nickel steel or aluminium. The maximum Allowable relief vapour setting (MARVS) is < 0. 7 bar.
* Independent Type 'C'
Type C Independent Tanks are deck pressure vessels or cylindrical pressure tanks mounted horizontally on two or more cradle-shaped foundations. The tanks may be fitted on, below or partly below deck and be both longitudinally and transversely located. Lobe-type tanks are commonly used at the forward end of the ship, to improve the poor utilization of the hull volume. This containment system is used for LPG,
Ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
and small scale
LNG
Liquefied natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume o ...
carriers. The material, if used for the construction of tanks designed to carry
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
, is 5% nickel steel. The maximum Allowable relief vapour setting (MARVS) is > 0. 7 bar.
*''Membrane''
Some other types such as:
* Internal insulation Type '1'
* Internal insulation Type '2'
* Integral
have been fully designed and approved but have not been commercially used yet.
Hazards on gas carriers
*
Toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...
Vinyl chloride
Vinyl chloride is an organochloride with the formula H2C =CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. It is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). Vinyl chloride is a ...
commonly carried on gas carriers is a known as a human
carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...
, particularly
liver cancer
Liver cancer, also known as hepatic cancer, primary hepatic cancer, or primary hepatic malignancy, is cancer that starts in the liver. Liver cancer can be primary in which the cancer starts in the liver, or it can be liver metastasis, or secondar ...
. It is not only dangerous when inhaled but can also be absorbed by the skin. Skin irritation and watering of the eyes indicate dangerous levels of VCM may be present in the atmosphere. 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.
Chlorine
Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...
and
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
are other toxic cargoes carried.
*
Flammability
A combustible material is a material that can burn (i.e., sustain a flame) in air under certain conditions. A material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort a ...
Almost all cargo vapours are flammable. When ignition occurs, it is not the liquid which burns but the evolved vapour that burns. Flameless explosions which result out of cold cargo liquid coming into sudden contact with water do not release much energy. Pool fires which are the result of a leaked pool of cargo liquid catching fire and
jet fires which are the result of the leak catching fire are grave hazards. Flash fires occur when there is a leak and does not ignite immediately but after the vapours travel some distance downwind and getting ignited and are extremely dangerous. Vapour cloud explosions and
boiling liquid expanding vapor explosion
A boiling liquid expanding vapor explosion (BLEVE, ) is an explosion caused by the rupture of a Pressure vessel, vessel containing a Compressed fluid, pressurized liquid that has attained a temperature sufficiently higher than its boiling po ...
s are the most grave flammability hazards on gas carriers.
*
Frostbite
Frostbite is a skin injury that occurs when someone is exposed to extremely low temperatures, causing the freezing of the skin or other tissues, commonly affecting the fingers, toes, nose, ears, cheeks and chin areas. Most often, frostbite occ ...
The cargoes are carried at extremely low temperatures, from , and hence
frostbite
Frostbite is a skin injury that occurs when someone is exposed to extremely low temperatures, causing the freezing of the skin or other tissues, commonly affecting the fingers, toes, nose, ears, cheeks and chin areas. Most often, frostbite occ ...
due to exposure of
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different ...
to the cold vapours or liquid is a very real hazard.
*
Asphyxia
Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are m ...
Asphyxia occurs when the blood cannot take a sufficient supply of
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
to the
brain
The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
. A person affected may experience headache, dizziness and inability to concentrate, followed by loss of
consciousness
Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...
. In sufficient concentrations any vapour may cause asphyxiation, whether toxic or not.
Health effects of specific cargoes carried on gas carriers
* Hazards of
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
[http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/ammonia/health_ammonia.html Canadian Centre for Occupational Health and Safety, Health Effects of Ammonia Gas]
1. Exposure to more than 2,000 ppm – fatal in 30 minutes, 6,000 ppm – fatal in minutes, 10,000 ppm – fatal and intolerable to unprotected
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different ...
.
2. Anhydrous ammonia is not dangerous when handled properly, but if not handled carefully it can be extremely dangerous. It is not as combustible as many other products that we use and handle every day. However, concentrations of gas burn and require precautions to avoid fires.
3. Mild exposure can cause irritation to
eye
An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system.
In higher organisms, the ey ...
,
nose
A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...
and
lung
The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...
tissues. Prolonged breathing can cause
suffocation
Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are m ...
. When large amounts are inhaled, the throat swells shut and victims suffocate. Exposure to vapours or liquid also can cause
blindness
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception. In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficul ...
4. The water-absorbing nature of anhydrous ammonia that causes the greatest injury (especially to the eyes, nose, throat or lungs), and which can cause permanent damage. It is a colourless gas at atmospheric pressure and normal temperature, but under pressure readily changes into a liquid. Anhydrous ammonia has a high affinity for water. 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. This attraction places the eyes, lungs, and skin at greatest risk because of their high moisture content.
Caustic burns result when the anhydrous ammonia dissolves into body tissue. Most deaths from anhydrous ammonia are caused by severe damage to the throat and lungs from a direct blast to the face. An additional concern is the low boiling point of anhydrous ammonia. The chemical freezes on contact at room temperature. It will cause burns similar to, but more severe than, those caused by dry ice. If exposed to severe cold flesh will become frozen. 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.
5. The human eye is a complex organ made up of about 80 percent water. Ammonia under pressure can cause extensive, almost immediate damage to the eye. The ammonia extracts the fluid and destroys eye cells and tissue in minutes.
6. Draining of ammonia into sea while pre-cooling of the hard-arm or during disconnection operations is not an eco-friendly operation. As a small quantity of ammonia as low as (LC50) is hazardous to Salmon as per ICSC, USA. Consumption of such fish could be dangerous to humans.
See also
*
List of gas carriers
*
List of tankers
This is a list of tanker (ship), tankers. The list includes merchant tankers as well as naval tankers that do not fall into more specialized lists such as List of replenishment ships of the Royal Fleet Auxiliary and List of Type T2 Tanker names.
...
*
LNG carrier
An LNG carrier is a tank ship designed for transporting liquefied natural gas (LNG).
Overview
The first oceangoing liquified natural gas tanker in the world was '' Methane Pioneer'', which entered service in 1959 with a carrying capacity of ...
*
Merchant navy
References
External links
Gas Tanker Advanced Course UK P&I Club The carriage of liquefied gasesSociety of International Gas Tanker and Terminal OperatorsWorld LNG Industry Standards
{{DEFAULTSORT:Gas Carrier
Merchant ships
Ship types
Petroleum transport