How much do you know about LNG ships?

  As one of the most popular clean energy sources in the 21st century, natural gas has always been optimistic about its future market. The world is facing a new technological revolution. In the future oceans, more and more large-scale LNG ships will sail among them to “pump gas and fuel” for human society.
  Since China became the world’s number one industrial power, the pace of becoming a maritime power has been accelerating. As the master of modern industry, the shipbuilding industry is known as the “Crown of Comprehensive Industry”. In this field, China has completed a magnificent turn from a chaser to a transcender. Hudong-Zhonghua Shipyard successfully built the world’s first 172,000-square-meter thin-film liquefied natural gas (LNG) ship in 2015. This is completely designed and built by China, with completely independent intellectual property rights, and the overall technology has reached the world’s advanced level. It can be said that the Chinese have taken a crucial step in the development of large-scale LNG ships, laying a solid foundation for the subsequent development of more advanced models; in April 2017, China’s first self-built domestic aircraft carrier “Shandong Ship” was officially launched; mid-2018 Shipbuilding Industry has signed large-scale luxury cruise construction contracts with the United States and Italy respectively. These indicate that the three jewels in the crown of the shipbuilding industry have basically taken shape, and have completed the transformation of the identity of a runner to a parallelist and finally a leader in the field of ship technology. It has thus achieved from quantitative to qualitative
  Next, we will tell the story of a large LNG ship.
  What is a large LNG ship?
  To a certain extent, the history of human civilization is a history of energy. In the view of the famous economist Schumpeter, the industrial revolution is a wave of large technological innovation activities. Every long cycle includes an industrial revolution and its digestion and absorption process. Since Britain first entered the age of industrialization in the early 1870s, the world economy has experienced four long waves. The rising period of the first long wave of the world economy occurred in 1782-1825, and the falling period was 1825-1835. During this rising period, technological innovations originating in the United Kingdom, represented by steam engines, promoted the emergence of emerging industries such as textiles and transportation. Among these emerging industries, the textile industry grew fastest and became the most mature industry at that time. Since technological innovation first occurred in the UK, the UK economy developed the fastest and quickly became the world economic center at that time. The rising period of the second long wave of the world economy was 1845-1873, and the falling period was 1873-1892. The invention and application of metallurgical technology enabled Britain to enter the steel age at that time, and the sharp rise of steel manufacturing became the leading industry that promoted the development of the world economy at that time. With the further adjustment of the world’s industrial structure, industrial modernization is emerging all over the world. The biggest beneficiary country during this rising period is the United States, whose economic strength is close to and surpassing that of the United Kingdom. The world economic center of gravity has shifted from the United Kingdom to the United States, and the world economic structure has also undergone a major transformation. The rising period of the third long wave of the world economy was 1892-1929, and the falling period was 1929-1948. Technological innovations such as electrical and automobile manufacturing not only led to the rapid development of the electrical, automobile and chemical industries, but also promoted the upgrading of industries in industrialized countries, and ultimately cultivated the automobile industry as the main industry at that time. Changes in the industrial structure led to changes in the organizational form of enterprises. Monopoly consortia became the main organizational form of enterprises at that time. The emergence of monopoly consortia marked the formation of private monopoly capitalism in the West. The United States first entered the era of private monopoly capitalism and became the center of world economic development. Driven by the economic development of the United States, European countries such as Canada, Japan, and Germany have also entered a period of capitalist heavy industry and chemical industry development. The rising period of the fourth long wave of the world economy occurred from 1945 to 1973. During this period, scientific and technological innovation came from more fields, the innovation and application of new technologies in the fields of electronic computers, biology, aerospace and new materials. While Western industrialized countries have successively entered state monopolies, the world’s economic center of gravity has also developed in a multi-polar direction. The three pillars of the United States, Japan, and Europe have taken initial shape, and the economies of many developing countries have made considerable progress. While the economy is making great progress, the demand for energy
  As one of the most popular clean energy sources in the 21st century, natural gas has always been optimistic about its future market. There is still no unified global natural gas market in international energy relations. There are only three regional markets in North America, Asia and Europe. With the development of shale gas, the supply of liquefied natural gas has greatly increased. The convenience and flexibility of liquefied natural gas trade will change the independent pattern of regional natural gas markets confined to pipeline transportation and accelerate the formation of the global natural gas market. According to the forecast of ExxonMobil, the average annual growth rate of global natural gas consumption demand before 2030 is 2.0%, while the average annual growth rate of oil and coal demand is only 0.7%. The medium and long-term natural gas demand forecast issued by the International Energy Agency (IEA) shows that by 2035, the total global natural gas demand will reach 5.1 trillion cubic meters, accounting for 25% of global energy demand. In the context of fierce competition in the global transportation industry, high oil prices, and requirements for energy conservation and emission reduction, shipbuilding companies have turned their attention to green energy with lower energy consumption due to cost and social responsibility. As the fuel for ships, liquefied natural gas can not only achieve zero emissions of sulfur oxides and particulate matter, but also reduce 85% to 90% nitrogen oxides and 15% to 20% carbon dioxide emissions. Liquefied natural gas has become the world’s preferred energy source due to its advantages of green, environmental protection and high efficiency. It has grown at an annual rate of about 12% and has become one of the world’s fastest-growing energy industries. The development of liquefied natural gas needs to be transported by liquefied natural gas ships. Because there are liquefied natural gas ships to transport liquefied natural gas, some small natural gas deposits that can be reached by liquefied natural gas ships can be exploited without the limitation of pipeline transportation of natural gas.
  According to Professor Zhang Yaoguang, in 1959, the American shipyard converted a wartime standard ship into an LNG carrier, and transported LNG from the United States to the United Kingdom. This was the earliest maritime transportation of LNG. In the early 1960s, Britain, France and other countries successively built some LNG ships with a capacity of 25,000 to 27,000 cubic meters. After trial transportation, large LNG ships appeared in the 1970s. In 1978, France built a giant liquefied natural gas ship with a capacity of 130,000 cubic meters, and its main scale (see the main scale of ships) exceeded 100,000 tons of oil tankers. The growth of LNG shipping volume has promoted the rapid development of the LNG ship market and related technologies. Since the UK built the world’s first new LNG ship in 1964, the number of LNG ships in the world has continued to grow rapidly. The LNG cabin has a capacity of 25,500 cubic meters. In 2003, 15 liquefied natural gas ships were produced with a total capacity of 1.937 million cubic meters. As of the beginning of May 2007, the global LNG carrier inventory reached 230, with a total cabin capacity of 28.18 million cubic meters. At the end of October 2011, the number of global LNG ships reached 365, with a total cabin capacity of 52.42 million cubic meters.
  Why is it difficult to build a large LNG ship?
  As one of the three jewels of shipbuilding in the world, the difficulty of building large LNG ships can be described as extraordinary. There are mainly the following obstacles.
  The first is the storage tank. Since the cargo carried is a cryogenic liquid at -163°C, the cargo containment system (cargo tank) is the key to a large LNG carrier. For safe and effective transportation, the cargo containment system of large LNG carriers faces two technical difficulties: one is reliable low-temperature insulation. Because only the cargo containment system has good low-temperature insulation technology, can it reduce the introduction of external heat, reduce the evaporation and corrosion of large-scale LNG ships, and prevent the low-temperature embrittlement damage caused by the leakage of large-scale LNG ships. The second is low temperature and cryogenic resistance, because the temperature of large LNG carriers will rise from -163℃ to 5℃ (large temperature difference) when loading and unloading large LNG carriers at the receiving station, and the ship’s hull shakes the liquid cargo enclosure when sailing. The structure of the protective system generates fatigue sloshing load, so the requirements for the container material are very high. It must still have high strength, good elongation plasticity, small expansion number and certain low temperature impact toughness under low temperature transportation environment. And also to ensure that the material has good weldability and economic practicability.

  The second is special welding technology. The cargo tank is the core of a large LNG ship. Generally speaking, the length of the Invar steel (Invar steel, non-expanding steel) weld of the 147,210 cubic meter large LNG ship is 130 kilometers, and the thickness of most of the Invar steel is only 0.7 mm. If there is a welding quality problem at a point, it will lead to the replacement and re-welding of a large adjacent plate. It takes at least 1,000 hours to repair a leak. The welding process includes manual welding and automatic welding. The plate involved is Invar steel, and the welding material involved is the special welding material M93. The welding technology of Invar steel has become a technology that must be overcome in the construction of large LNG ships. |Key.
  The third is the insulated box. The cargo carried by the large-scale LNG carrier is LNG with a temperature of -163°C, and the LNG is insulated from the hull through a two-layer insulation box installed on the whole ship. On a large LNG ship of 147,210 cubic meters, 55,000 insulated boxes of more than 1,100 different types are needed, and the accuracy of the boxes must be controlled within a tolerance of 0.5 mm.
  The fourth is the prefabricated parts of Yin tile. Invar prefab is an important part of a large LNG ship. It is a connection between the membrane and the hull. It includes invar tube, invar trihedron and other invar small parts. In the past, bulk carriers, oil tankers and container ships were built. There is no such component. On the large-scale LNG ship, there are about 400 invar pipes and trihedrons, and 60,000 invar small parts. The production of all these invar preforms has not only quantitative requirements, but also strict precision control requirements. Large-scale liquefied natural gas ships must tackle key problems and solve the processing technology of these key parts.
  Looking to the future, large-scale LNG carriers worldwide in terms of production technology and will be showing some of the following trends.
  The first is the technical field. At present, the world is facing a new technological revolution. New industries such as microelectronics and computer technology, bioengineering, new materials, new energy, laser and optical fiber communications, space engineering, and ocean engineering have sprung up. This has brought new challenges to all nations in the world. The new technological era will have a considerable impact on large gas carriers. Specifically, after the outbreak of the new crown pneumonia, ships have become a major carrier of the virus. Unmanned will become an important direction for the future development of all types of ships, and large-scale LNG ships conduct more transcontinental voyages, so the development of unmanned and intelligent technologies is particularly important. Therefore, the future large-scale LNG ships will make greater progress in the field of automation and intelligence.
  The second is that manufacturers of large LNG ships will remain concentrated. In general, the world’s shipbuilding industry is concentrated in the middle latitudes of the east and west sides of the Eurasian continent with excellent harbors and water and land transportation hubs. Shipbuilding companies are mostly located in areas that consume large amounts of raw materials and are close to the iron and steel industry, machinery industry, or integrated industry. At present, manufacturers of large-scale LNG ships are mainly concentrated in the three major shipbuilding powers of China, Japan and South Korea. According to related reports from South Korea, the market for large-scale LNG ships is booming. By 2025, 60.3% of new ship orders will be large-scale LNG ships. However, the manufacturing of large LNG ships is still being further concentrated. On June 2, 2020, the three major shipbuilding giants of South Korea’s Hyundai Heavy Industries, Samsung Heavy Industries, and Daewoo Shipbuilding successfully won an order for 100 large-scale LNG ships in Qatar, with a project scale of 23.6 trillion won (about 137.4 billion yuan). On June 30, according to the Xinmin Evening News, Hudong Zhonghua Shipbuilding (Group) Co., Ltd. (hereinafter referred to as Hudong Zhonghua), PetroChina and China COSCO Shipping Group Co., Ltd. signed three large-scale LNG carriers of 174,000 cubic meters. The total amount of construction contracts and time charter contracts amounts to 3.9 billion yuan. In 2018, there were a total of 76 large-scale LNG ship orders worldwide, of which South Korea won 66 ships, while China only won 5 ships during the same period, and Japan only had one. With the shift in global energy demand to environmentally friendly energy, the shipbuilding market has also shifted its focus from coal and petroleum-powered ships to natural gas-powered ships. At present, there are 13 shipbuilding companies participating in the global LNG ship manufacturing market, of which only 8 shipyards have received orders for LNG-powered ships, including 3 Korean shipyards (Daewoo Shipbuilding, Hyundai Heavy Industries, and Samsung Heavy Industries) and 1 Chinese shipyard (Hudong China) and 4 Japanese shipyards (Mitsubishi Heavy Industries, Kawasaki Heavy Industries, Japan Maritime Union, and Imabari Shipbuilding). In the future, Japanese shipyards will likely adopt an alliance with Chinese shipyards to give play to their respective advantages in technology, capital, and cost, thereby competing with Korean shipyards. This shows that the world’s large-scale LNG ship orders are still the “Romance of the Three Kingdoms”.
  It is foreseeable that in the future oceans, more and more large-scale LNG ships will sail among them to “pump gas and fuel” for human society.