Second, natural gas needs to be transported at a very low temperature to be stored, and the characteristics of Yinwa Steel mean that it will have an advantage in building LNG ships. The thickness is only 0.7 mm, which is thinner than paper and can effectively prevent the hull from cold cracking in ultra-cold environment. Its very thin thickness also makes welding very difficult. Usually only very advanced welders can finish this job. For the first time in this country, a group of workers can weld Invar steel. Although this is a technical job, it is quite difficult to learn this skill. Even welders need to spend hundreds of thousands of dollars on training and receive strict study and education abroad.
Thirdly, the welding of silver tile steel is not a simple technical activity, which requires not only personal physical strength, but also the wisdom of technicians. The core of the ship is the inner wall of the cargo hold. The inner wall is welded by invar steel plate. The thin part is only 0.7 mm, but the welding length may reach hundreds of kilometers. After welding, all welds have to undergo strict air tightness test, which is a very tiring job. Strictly speaking, this metal is fragile, because once it is touched by a worker's hand, it may rust. As a material, silver tile steel is measured in kilograms instead of tons. There are only two factories in the world that can produce silver tile steel.
You know, most metals and alloys will expand when heated, expand when heated, and contract when cooled, so their thermal expansion coefficients will show a linear relationship. However, the thermal expansion of this Invar steel alloy does not conform to the normal expansion law and belongs to abnormal thermal expansion. Invar steel can maintain its shape stability and strength in a large temperature bandwidth, and can maintain its normal shape under high and low temperature conditions, so it is the only material for transporting and storing liquefied gas.