LNG ship: also called LNG ship, referred to as “LNG ship”. It refers to a “ship” that specializes in transporting LIQUEFIED natural gas. The earliest LNG carrier was the 5,100-square-meter Methane Lightor, which was converted from an old tanker in 1958. According to the structure of liquid cargo tank can be divided into independent storage tank type and membrane type. The former is the cylindrical, tank, spherical and other shapes of storage tanks placed in the ship; The latter adopts double shell structure, and the inner shell is the carrying shell of the liquid cargo tank. Compared with the independent type, the membrane type has the advantages of high volume utilization rate and light structure weight. Therefore, the new LIQUEFIED natural gas ship, especially the large one, mostly adopts the membrane structure. Liquefied natural gas carrier equipment complex, high technical requirements, high cost. In 2005, China had its first batch of 16 workers who mastered the welding technique. Steel plates as thin as paper and welding as embroidery It might take only four seconds to walk, but it took Zhang Dongwei five hours to weld a seam of that length. Zhang Dongwei said: “I burn out of the weld basically can be identified, are a molding, like fish scales more uniform, my personal pursuit is like embroidery, a needle a needle is very uniform.” Zhang Dongwei is welding the liner of China’s no. 9 LNG ship, the core of the entire ship, which requires welders to join pieces of paper-thin Yin tile steel sheet together, like clothes. Invar (also known as Yin steel) Is a nickel-iron alloy, its thermal expansion coefficient is very low, can maintain a fixed length over a wide temperature range. Its thermoelastic coefficient is virtually zero over a wide temperature range (that is, young’s modulus is constant) and its thermal expansion coefficient is low. This alloy in magnetic temperature near the Curie point significantly reduce the thermal expansion coefficient, the so-called abnormal thermal expansion occurs, which can be a very wide range of temperatures near room temperature, or even close to zero expansion coefficient is small, a face-centered cubic structure, its brand is 4 j36, its Chinese name is invar, English name is invar alloy (invar), That means the volume doesn’t change. In general, the vast majority of metals and gold are both in expands when heated, cooled volume contraction, the thermal expansion coefficient increase linearly, but the periodic table of iron, nickel, cobalt and other transition of some alloy elements, because they are ferromagnetic, at a certain temperature range, the expansion of the thermal expansion does not conform to the normal rules, Abnormal thermal expansion with the Ingvar effect, that is, its mechanism is related to chemical composition and magnetism. A LNG ship, Yin tile steel welding’s length is 130 kilometers, while 90% is automatic welding, but there are 13 km special position of weld, need welder done manually, if even a needle size funnelled to appear on the weld, it may cause the ship gas explosion, some people say that the LNG carrier can move like a bomb. In order to avoid the leakage of welding seams, Zhang Dongwei requires that there should be no pause in the welding process, so he often takes three or four hours to stop working. Practice skills to pass the examination of foreign examiners thumbs up Yin Wa welding super-strong arc light is very exciting to the eyes, and the welding foam also has certain harm to the body, at the beginning of the apprentice, many companions watched the master welding after one or two hours, but only Zhang Dongwei would not leave. Yin Wa welding requirements for welders are very high, to become Yin Wa welders need to go through strict screening and training, the elimination rate is very high, early training costs as high as hundreds of thousands, comparable to pilots, and finally through the French GTT strict examination certification before the certificate of post welding, and at present in China, There are only about 200 Yin Wa welders who have welder certificates issued by GTT. Zhang Dongwei said: “I told my teacher, I have been determined I technology must be more than teacher, my own train an apprentice, is what I want I take apprentice technology will also be able to more than I, if everyone is a step ahead, the technical aspects of the talents, our country must be succeed somebody.” Fishing practice temper hand accurate heart more stable Yin tile steel is a kind of ultra-low temperature steel, as thin as paper, easy to rust, the thinest place by hand, 24 hours after the rust will wear. Therefore, in the welding, there can not be a bead of sweat, a handprint, which requires workers in the welding, not only the hand accurate, but also to the heart stable, any emotional fluctuations of welders, may directly affect the quality of welding. To hone his mental state, Zhang spent his spare time fishing to temper himself. Due to the tight construction schedule, Zhang dongwei often returns home only once a week, but his father’s big boat has become the favorite of his two daughters. As an equipment manufacturing industry of power, if only research and development of high-end talent, it’s become a manufacturing power, therefore need Yin tile welder such powers artisans, the so-called fou 36 line out of the top, China is also have such as Yin welder these front line workers, the rapid development to become a manufacturing powerhouse.