Ships that simplify the transportation and supply of large quantities of liquefied and gaseous cargo are called oil tankers. Cargo such as organic compounds, chemicals, fuels, hydrocarbons (liquefied natural gas, liquefied petroleum gas, etc.) and even alcoholic beverages are transported by tanker.
The history of oil tankers
The emergence of semi tanker for sale dates back to the 19th century. At the time, the era of industrial prosperity was slowly developing, and before the end of the 19th century, the technology simply did not support transporting bulk liquids and gases or selling them on the market. The first tankers were used by the oil industry to transport refined fuel in bulk from refineries to consumers. The Zoroaster was the first ship in the world to transport liquid cargoes in oil tanks, contrary to the idea of transporting liquid cargoes in wooden drums and drums, which were very unsafe and time-consuming. In 1861, Elizabeth Watts sailed to England with a ship carrying 224 tons of oil, the first to carry liquefied material. The Gluckauf was the first tanker to be fitted with a separate tank in the hull.
Classification of oil tanker
Oil tankers can be classified largely by type, purpose, hull and size. Now let's look at each type of tanker based on these factors.
According to the type, oil tankers can be divided into: oil tanker, tank tanker, chemical tanker.
1. Oil tankers are ships used to transport crude oil, gasoline and gasoline products in bulk, which can be divided into product oil tankers and crude oil tankers. Crude oil tankers are designed to transport crude oil from the production site to the refinery, where it is refined to various grades, and the product is extracted and distributed. The product tanker is used to transport a variety of petroleum products, mainly of various grades, coated with epoxy resin to protect the cargo from chemicals and to facilitate tank cleaning.
2. Equipped with the most advanced technology for the transport of compressed gas in bulk, tank vessels can be further classified as full ballast, semi-ballast, vinyl, fully frozen liquefied petroleum gas and liquefied natural gas vessels.
The fully pressurized tank is made of carbon steel with a design pressure of 18 bar (Type C) and is not insulated. Tanks are usually small in size due to their design pressure and weight. Goods can be transferred directly through compressors or pumps.
Semi-steamers are designed to resemble full steamboat construction, with a maximum working pressure of 5-7 bar, and are popular in Mediterranean and northern European coastal areas.
Vinyl ships can carry all types of cargo, but also have special facilities to transport chemical gases or liquefied petroleum gas. They are equipped with Type C pressure tanks of 1000-1200 cubic meters. Insulation and liquefaction units are installed on this type of tank.
Fully frozen liquefied petroleum gas vessels have a prismatic tank, making them suitable for transporting cargo in extremely cold temperatures as low as -48 degrees Celsius.
LNG carriers transport LNG at -162 degrees Celsius and are equipped with separate cargo tanks or membrane tanks.
These tankers can be further divided according to the cargo control system.
MOSS Type (Spherical A type) : The Norwegian company MOSS designed this system, so the system is named after them. Most MOSS type boats have 4-5 storage tanks with a working pressure of 22kPa or 3.2psi, and can be increased if needed.
Ishikawa (Prismatic B) : Designed by Ishikawa Heavy Industries and used by only two vessels, these self-supporting prismatic B tanks solve the problem of film sloshing in the transport tanks and reduce accidental damage to the interior caused by equipment leaks.
TGZ MARKIII: Designed by Technigaz, this film is made mainly of 12mm thick stainless steel. The secondary membrane is followed by the primary insulation, which is a new secondary insulation, all supported from the outside by the container structure.
GT96: Made of a material called Yinwa, Gaztransport designed as primary and secondary membranes without thermal shrinkage. The plywood box was insulated with perlite and flushed with nitrogen.
Type CS1: Refers to Gaztransport and Technigaz design Joint System 1. The first barrier is made of Yinwa and the second is made of three layers. However, only one shipyard has produced three ships using the membrane system.
3. Chemical tankers are used to transport various types of liquid chemicals. Due to the size limitations of port and shore-based facilities and the specific nature of the cargo, these ships are designed specifically for consistency and are smaller in size compared to oil tankers, with tanks often coated with phenolic epoxy or zinc paint or stainless steel depending on the type of chemicals being carried.
Oil tankers are divided into the following categories according to their purpose.
Mud tankers: Transport scrap and all water insoluble materials used to transport sintered products such as fertilizer to the production site.
Hydrogen tanker: Used to transport liquefied hydrogen gas in bulk. Kawasaki Heavy Industries was the first company to design a hydrogen tank ship.
Juice can boats: Designed to transport large quantities of fresh or concentrated juice. These tankers are equipped with preservation equipment and temperature control systems to help keep the cargo fresh at all times.
Wine vessel: Vessel designed to transport wine from its place of production to its final destination.
According to hull type, oil tankers can be further divided into the familiar Panamax type, Afra type, Suez type, very large oil tankers and ULCC with a capacity of 500,000 tons.
The design of oil tanker
The general arrangement of the tanker is shown below. Cargo tanks are similar in size to maintain balance and symmetry, each tank is designed to depend on the ship's intended gross deadweight ton, and the main deck usually houses a network of pipes to load and unload cargo.
The signature design of the tanker is the bulbous bow, which is used to improve the ship's power efficiency. Design can be divided into three categories.
Delta volume is concentrated in the lower half and more concentrated in the upper half. This feature is beneficial for use on ships with frequent waterline changes, as a more concentrated volume of the lower section ensures immersion into a wider range of waterline and load conditions.
The O-shape has its maximum volume concentrated in the center and is used on most ships that require a cylindrical bow shape.
The Nabla shape is almost like a teardrop, with a more concentrated volume at the top. This shape is preferred on ships equipped with special capabilities.