Energy Transporta
The world runs on crude oil and counts on tankers to keep the supply flowing. Tankers also transport a broad range of refined petroleum products including gasoline, as well as liquid chemical products.
In recent years, natural gas has taken center stage as an environment-friendly energy resource. It travels to markets around the world in LNG carriers that are like floating vacuum flasks.
Like other vessels, tankers vary in size and configuration depending on the cargo they carry. Their common characteristic is that they connect with some type of pipeline on shore to load and discharge their cargo.
Ocean-going Vacuum Flasks Transport LNG

Tankers carrying liquefied natural gas are called LNG carriers. In gaseous form, it would be impossible to transport methane-based natural gas, because of its immense volume. But when super-chilled to its liquid state, natural gas takes up only 1/600th of its gaseous volume, allowing efficient transport.

LNG’s boiling point is extremely low minus 161.5°C,so transporting it by sea requires a dvanced technologies such as tanks made of materials especially engineered to withstand ultralow temperatures – ferronickel, stainless steel, and aluminum alloys. Emergency shut down devices are also critical to prevent incidents during loading or discharging. Because LNG is transported almost at its boiling point, many LNG carriers adopt steam turbine engines that can run on gas that boils off from the cargo tanks. Tank configurations include the Moss type (independent spherical cargo tanks) and the membrane type (composed of thin stainless steel).

Vessels Play a Key Role in Offshore Energy Production

Some vessels have onboard plant facilities and equipment allowing them to serve as floating energy plants. These include Floating Storage and Regasification Units (FSRUs) and Floating Production, Storage, and Offloading (FPSO) systems.

  • FSRUs receive cargo from LNG carriers at receiving terminals, store it in their tanks, and regasify it according to demand, and send the gas under high pressure to onshore pipelines.
  • FPSOs produce crude oil and gas from fluids extracted from subsea reservoirs using onboard plant facilities and equipment.

Tankers Tailored to Fit Various Cargoes

Whether they transport crude oil, petroleum, or chemical products, tankers share the following characteristics:

When people think of tankers, the first thing that comes to mind is oil tankers that transport petroleum. Crude oil, in particular, plays such a vital role in Japanese industries and people’s lives, it must be transported safely, reliably, and on a massive scale — usually in ships called Very Large Crude oil Carriers (VLCCs) ranging in size from 200,000 DWT to 320,000 DWT.

The cargo tanks on these vessels are separated into two or three blocks crosswise and about five blocks lengthwise, allowing the ship to transport different types of cargoes. In general, cargo is discharged offshore at a sea berth, connected by a pipeline to the terminal on shore.

Basically, the hull structure and loading/discharging methods are the same as crude oil tankers, but some chemical and product tankers have more tanks so they can transport a wider variety of cargoes. Usually, each tank has its own pipelines and cargo pumps to prevent cargo-contamination.
Product tankers carry petroleum products such as gasoline, naphtha, kerosene, and diesel oil. These ships are essential in transporting cargo to areas that do not have facilities to refine crude oil. There are generally three classes of product/chemical tankers. These days, larger vessels are becoming more common as demand increases.

 Product Tanker Names by Size
  MR type (medium range): 25,000 ‐ 55,000 DWT
  LR I type (large range 1): 55,000 ‐ 80,000 DWT
  LR II type (large range 2): 80,000 ‐ 160,000 DWT

Chemical tankers transport liquefied chemical products such as benzene, toluene, and alcohol products.
The cargoes transported by product/chemical tankers are more corrosive than crude oil, so tanks and pipelines are usually made of stainless steel, with special coatings inside.

This type of tanker carries liquefied petroleum gas (LPG) such as propane and butane. Some LPG tankers are multipurpose vessels that can also transport liquefied chemical gases including liquefied ammonia, which is a raw material for textile and fertilizer production.
As the boiling points of liquefied propane and liquefied butane are higher than that of LNG (minus 42.4° and minus 0.5° respectively), the requirements for hull and tank structures and materials are not as strict as LNG carriers. Therefore, there are many smaller coastal LPG carriers as well. There are three basic types of LPG carriers: fully pressurized, fully refrigerated at atmospheric pressure, and semi-pressurized and refrigerated. Most large-scale ocean-going LPG carriers are the refrigerated type.

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