Tanker (ship)

A tanker is a ship specially equipped for transporting liquid or gaseous substances.

Examples are: crude oil, oil as a finished product, fuel, liquefied petroleum gas, water, juice.

The silhouette of a tanker is easily distinguished from the other ships. He has a flat deck that hardly bears structures except the bridge. It does not require loading gear ( mounted on deck cranes), except for the amidships mounted on all tank vessels, the so-called Manifoldkran can be lifted on board with the hoses from country to connect them with the conduction system of the ship. These connectors (also called Manifold ) are also clearly visible from a distance.

Tankers have pumps for deletion ( seamanly for " unloaded ") of the cargo on board. Also be monitored for tankers, as is now in almost all vessels with loading and unloading operations a loading computer. This allows a prediction on the distribution of the forces ( buoyancy and the weight of the load) acting on the ship.

Main components of the marine engineering are the main engine with auxiliary units, boiler plant, auxiliary diesel generators for power generation, inert gas system, tank washing systems and the charge pump with a single output of over 10,000 tons per hour.

When flammable tank charges nowadays ship fires and explosions are filling the voids of the tanks, eg above the cargo avoided by an inert gas. The inert gas replaces the previous, oxygenated tank atmosphere by almost oxygen-free gas, so as to prevent that the charge gases may ignite. The inert gas may be a specially prepared, produced on the ship combustion gas ( exhaust gas ); but it can also be any other gas, does not form a reactive mixture with the respective load can be used.

Oil Tanker

Oil tankers are ships that are built specifically for the transport of oil.

Oil tankers that supply the European market with crude oil from the oil-producing countries, almost always have a size of more than 100,000 GRT. The drive today's oil tankers by means of a heavy oil- fueled main engine with direct drive of the drive shaft with a fixed propeller. The main machine is usually a slow running two -stroke diesel engine at about 100 revolutions / minute. For smaller ships, medium-speed four-stroke engines are found as well as diesel-electric drives in which the main engine drives a generator and the electricity generated in this way is also used to drive the propeller. The usual in the past steam turbine drives are no longer produced because of the low efficiency and high fuel prices. Even today, alternatives are being sought in the drive, then there exists a concept study on environmentally friendly oil tankers by natural gas. Crude oil is loaded in the heated state, and during the entire voyage stay warm in order to be pumped in the port of discharge can. To heat the charge adequately sized boilers are therefore installed on board. The largest ever built oil tanker, the Jahre Viking was able to load 652 million liters of crude oil.

Also in the inland navigation the tanker plays a major role, it is in the main product tankers. Oil is hardly transported by inland waterways. The largest inland tanker can carry up to 9900 tons, even more are under construction.

Since speed the transport of oil is not particularly important are oil tanker with about 15 knots (28 km / h) relatively slow ships.

Oil tankers reach as many other cargo ships an age of 20 to 25 years, after which they are scrapped. For this they are driven at shipbreaking yards in Alang, such as at spring tide on the beach, then disassembled and largely recycled.

Size Growth

Since the transport costs per tonne of cargo are lower in larger vessels, larger oil tankers were ever built.

Note to table: Records / maximum values ​​in each category and their explanation are highlighted in bold.

Oil tankers over 200,000 tons as VLCC ( Very Large Crude Carrier ) tankers over 320,000 tons as ULCC (Ultra Large Crude Carrier) respectively. With a total weight of more than 250,000 tons one speaks of a supertanker. Despite its size, the largest tankers usually come with 15 to 25 man crew. Double hull tankers over 300,000 tons are called VPLUS

However, the size and growth brings not only benefits, but also leads to problems. In the construction of ships of this size it is important to avoid structural problems because the high stresses would otherwise lead to deformations and cracks on the hull. Due to the large depth only a few ports can be started, also they are too large for the Panama Canal. The Suez Canal, however, can be ridden in empty trip by 450,000 - dwt ULCC tankers. In order to also earn through laden ULCC, a pipeline -tank system was installed along the channel, so that at the beginning of the oil is pumped up to the allowable draft and shall be maintained by the channel in tanks for recovery. The idea to build such a large ocean-going vessels is due, inter alia, on the closure of the Suez Canal in the years 1967-1975. During this time, all vessels from the Persian Gulf had to drive around on the way to U.S. or Europe, the Cape of Good Hope in South Africa.

Two - hull tankers and double hull tankers

A two - hull tankers is a transport ship for transport of liquid cargo, which has a double outer shell. The distance between the two cases to each other is usually 2-3 meters.

Unlike conventional single-hull tankers, these are designed to provide a higher level of security against leakage of the cargo under normal operation. The double hull tankers must however be used as a ballast tank to the vessel - according to the current load - trim can ( as ballast seawater is used for ships, which is pumped into the respective tanks ).

By the raw water, the inner walls of the shell of an extreme corrosion are exposed, so that regular inspections and renovations to the protective coating are required for the two- hull tankers really can provide increased security.

After the disaster of the Exxon Valdez in March 1989, the International Maritime Organization (IMO ) has decided to constitute a regulatory authority that all tankers to be built from 1996 and have over 5000 tons Shipping Weight must be equipped with a double hull.

After the Erika disaster (1999), the IMO has decided that from 2015, only oil tankers with double-walled outer shells may sail the world's oceans.

Originally, the development of the double- tanker had not been made ​​for safety reasons, but to energy ( and therefore costs ) to save the transportation of hot materials such as bitumen, molasses or paraffin. A double hull offers a good thermal insulation.

With the entry into force of the 88th amendment of the fifth SOLAS as amended on 1 July 2006, however, the double hull construction is also a mandatory element in the construction of bulk carriers for the purpose of safety of life at sea ( and a side effect, also to protect life on land ). But due to the explicit resistance of Greece towards this has still not been prescribed on board tankers pure, but only on board ships which either dry bulk transport (eg ore, soya, scrap, etc. ) or as a " combination ships have " both cargo holds and tanks on board at the same time (eg crude oil ) to be able to carry dry bulk and liquid.

LNG carriers

LNG carriers serve the maritime transport liquefied gases in bulk in permanently installed cargo tanks. Transported gases are beyond industrial gases, especially liquefied natural gas ( LNG liquefied natural gas) and LPG ( liquefied petroleum gas ). LNG carriers are a flexible alternative to the pipeline transport for the purpose of energy supply. The efficient transport of gases requires a liquefaction. This liquefaction causes a significant reduction in volume (LPG: 1/ 260 LNG: 1/ 600) and can be reached depending on the nature of the gas, both by increasing the pressure as well as by lowering the temperature. The Methane Pioneer was the world's first LNG tanker. Since the different varieties of liquid gases differ considerably in their compressibility, each specific tank ships are built for the different types of gas.

Binding international standards on the construction and equipment of liquefied gas tankers adopted in IMO Gas Code (IGC ), IMO. This code typed the ships by their ability to survive damage ( eg caused by collision or stranding ) to survive. Type 1G - tankers are the safest in terms of a possible escape of cargo ships.

The following liquefied gases are transported through eg:

• Type 1G - tanker: chlorine, ethylene oxide, methyl bromide
• Type 2G tanker: ethane, ethylene, methane (LNG ), typical for LNG tankers
• Type 2G/2PG-Tanker acetaldehyde, ammonia, butadiene, butylene, dimethylamine, ethylamine, ethyl chloride, methyl chloride, propylene, vinyl chloride, and butane, propane (LPG), typical of LPG tanker
• Type 3G tanker: Nitrogen, various safety refrigerants ( Rxx )

The characteristic for LNG LNG carriers form is characterized by a plurality of spherical tanks, the upper half is always higher than the deck, and makes this type of ship so very clear. The spherical shape of the individual tanks for both pressurized tanks (LPG ) and an optimum isolation of the best design. However, there are also LNG carriers, where the nearly rectangular tanks almost completely located in the fuselage and can be easily confused with oil tankers. These are so-called membrane tankers. A LPG tankers used to transport liquefied gas that is similar to lighter gas at room temperature under moderate pressure (up to 20 bar) can be liquefied. For LPG cooling is not necessary.

In contrast, LNG carriers transport liquefied natural gas by freezing in highly insulated tanks. The first ship of this type was from the C1 - ship Normarti for tankers converted Methane Pioneer (aluminum tanks with wooden insulation, 5,123 m³ total tank volume, start the maiden voyage on January 29, 1959 by Lake Charles, Louisiana).

With this in recent years increasingly to be seen method of transportation is a trend towards larger units should be noted in addition to the currently prevailing LNG tankers with 125000-147000 m³ total tank volume, divided into usually 4 to 6 tanks, vessels of up to 250,000 m³ tank capacity are planned. The liquefied natural gas is transported ( eg max. 230 mbar membrane tank ) and the corresponding temperature of from -164 ° C to -161 ° C at a slight overpressure.

In spite of the insulation ( Perlitisolierung ) of the LNG tanker carries out the slow heating of the tank to vaporize a portion of the charge, the so-called " boil-off ". Thus, the pressure in the tank does not accept excessively high values ​​, the evaporated gas can escape. Instead of a free flow of this gas is energy used to produce steam and finally for propulsion and power generation (LNG as fuel for ships). LNG tankers are designed for this reason mainly as a turbine ships for heavy oil and / or natural gas operation. In case of excessive boil-off gas, the overproduction of steam in the auxiliary or main condenser is condensed to seawater, so that no normal ship operation state of methane has to be blown off (as natural gas, the main constituent) in the atmosphere. In this capacity limits of the capacitors is exceeded, the boil-off gas through a pole ( vent raiser ) is blown into the atmosphere to keep the tank pressure within the allowable range.

A few new buildings are equipped with diesel-electric drive, with natural gas and / or diesel fuel or heavy fuel oil is burned in the engines. In the long term, the turbine ships are being displaced by the motor boats with gas re- liquefaction plant in the LNG shipping. The trend is heralded in the new business to this.

A re- freezing, ie re-liquefaction, LNG on board was considered until recently to be too expensive. Some older ships are equipped with re-liquefaction plants, but these were due to technical problems and lack of profitability never really used. Some modern LNG tankers are prepared in anticipation of rising natural gas prices for the installation of a re-liquefaction plant and can therefore be retrofitted if necessary unproblematic (eg TGT "British Trader", foundations, flanges, and a comparatively large heavy oil tank capacity are available ).

Currently, around 200 LNG tankers in operation. New ships of this type are built primarily in South Korea, but also in Spain and France. LNG tankers are due to the high construction costs (typically U.S. $ 200 million) designed for a service life of about 40 years and usually only laid the keel if a long-term charter (20 years ) is available. But here in recent times a tendency to form a spot market, as observed in the oil business.

The currently largest in the planning stages, LNG tankers will be equipped with 266,000 m³ tank volume. Are driven by diesel engines, these vessels (DRL - drive system). The boil-off gas is reliquefied and supplied to the load again. The first ship of this so-called Q -Max class is gone in 2009 QGTC ride.

Environmental hazards

The expiring at oil tanker accidents caused great damage to nature ( " oil spill "). Waterfowl and aquatic mammals are glued feathers or fur, by toxic ingredients go fish, mussels and crabs based on which many other animals the basic food is withdrawn.

To reduce the risk of leakage of crude oil in ship collision or stranding on a reef, decided the International Maritime Organization ( IMO), that only two- hull tankers should be built. All single-hull tankers to be decommissioned by 2015.

Meanwhile Technical improvements and stricter Sicherheitssregeln show effect of the approximately three million tons of oil entering the oceans annually, about thirteen percent of tanker accidents ( June 2005 Balance ) come just yet. Far greater amounts of oil from entering the other hand, from the engines of boats, cars, oil platforms at sea, illegal discharges and other oil-lubricated machinery and equipment in the world's oceans. Here, the environmentally sensitive coastal areas and estuaries are the most affected by pollution.

The use of ballast water is a growing environmental problem dar. With the sea water-dwelling animals and plants is transported between the oceans. By the early 20th century, the Chinese mitten crab was thereby brought into European waters. If the tanks are emptied at the destination, enter the organisms into new habitats where natural enemies may be missing. If these invasive species can survive under the new conditions seeklimatischen, they pose a threat to the ecological balance dar.

At the end of the service life of ships is scrapping, especially in India, Pakistan and Bangladesh. A ship is set to start with on the beach and decomposed under extremely harsh, hazardous work conditions. Due to hazardous environmental impact, there was opposition ships with verbautem asbestos, are also problematic radioactive smoke detectors and of course oil, fuel and cargo residues.

Stopping distance

The International Maritime Organization requires that ships must come to a halt at a Notstoppmanöver from full speed within 15 ( in exceptional cases 20) ship lengths. However, such emergency stop maneuver loads the main machine, its foundations and the shaft so strong that it is practiced except at scrutineering only in exceptional cases. From the regulations resulting in a maximum of 450 m in length a distance of up to 9 km to the stopping of the vehicle. Longer stopping distances occur when the ship is not braked or slowed his steady ride.

Series of experiments with unloaded large tankers of 250,000 deadweight tons and 390,000 were outstanding stopping distances from 1.32 to 3.4 nautical miles that have been achieved in periods 12 to 27 minutes.

Other forms

• Asphalt tanker
• Orange juice concentrate tanker
• Product and chemical tanker