For shipbuilding companies, steel is the main raw material, and the scale and efficiency of ship enterprises are evaluated. The annual steel processing volume is one of the important indicators. The level of steel quality plays an important role in the normal production work of shipbuilding enterprises. Tan Jie, Vice President of Ship Design and Research Institute of China Rongsheng Heavy Industry Group Co., Ltd. put forward at the 4th China Steel Shipbuilding and Ocean Engineering Steel Development Forum in 2012. From the current market situation of marine steel products, steel companies can In terms of improving steel standards, it will be able to take the initiative in the future market competition.
Variety, specifications need to be improved
At present, the specifications of marine steel plates produced by China's iron and steel enterprises still need to be improved. Tan Jie said that the construction of a ship involves thousands of varieties of steel for shipbuilding. In order to meet the design requirements for large-tonnage ships, the shipyard has to order goods for a single ship at several steel companies at the same time, and the width of the ship is often Can not meet the requirements, it can only be obtained by welding the desired product, which not only reduces the utilization of steel, but also increased the labor intensity of shipbuilding. The large-scale construction of ships requires that the shipboard steel plate develops to a width of 5 meters and a length of 25 meters. Its type covers almost all grades, and the quality and dimensional accuracy of marine steels are more demanding.
As China’s ability to build high-tech ships continues to increase, the demand for special-performance steels has also increased dramatically. For example, LNG ships using low-temperature pressure vessel plates not only meet the requirements of high-strength shipboards, but also satisfy 163 °C temperature resistance pressure vessel performance requirements. Ship types such as new-type container ships require that the types of ships cover almost all grades, that is, the number of varieties will reach more than 1,200, and will be developed for Class F, Class Z steel ships and profiles. In terms of marine sections, the demand for large-sized ball flat steels and large unequal thickness angle steels will also increase, and the requirements for seamless tube wall thickness uniformity and roundness accuracy will increase.
The use of marine stainless steel will increase, especially in the construction of LNG ships and LPG vessels. Stainless steel and nickel-base corrosion-resistant alloys will be used in large quantities. Currently, they are mainly imported from Germany; the former is mainly used for liquids. The cargo tank dome structure, which is mainly used for the tank maintenance system and LPG tank steel due to the extremely low expansion coefficient. At the same time, the liners of LNG and chemical tankers use a large amount of 205 bidirectional stainless steel, which weighs about 10% of the entire ship weight.
In addition, the demand for high-strength ships is also increasing. High-strength steels are generally used on large-scale bulk carriers, container ships, oil tankers and offshore engineering vessels. As the shipbuilding industry is moving toward large-scale, high-speed and multi-purpose manufacturing technologies, the demand for high-tech vessels is also increasing. Therefore, the general trend is that the amount of ordinary A-class plates will gradually decrease, and the demand for low-alloy and high-strength ship plates will increase.
Shipboard quality needs to be improved
Judging from the shipboard produced by China's steel companies, the quality of homemade shipboards cannot be compared with that of Japanese companies such as Nippon Steel and Korean POSCO. At present, the high-pressure water in most plate mills in China suffers from problems such as insufficient scale pressure, high heating temperature, long heating time, and excessive air flow in the furnace. This can easily cause pitting on the surface of the steel plate.
In addition, the automatic steel plate length measurement, width measurement, thickness measurement and other equipment of the domestic steel enterprises are not perfect, which can easily lead to the dimensional deviation of the finished steel plate, especially the deviation of the diagonal lines. Tan Jie suggested that in order to further develop the market, steel companies must improve on these key issues and continuously improve the quality of shipbuilding.
New standards, new norms need to be thoroughly understood
With the increasing global environmental problems, the International Maritime Organization (IMO) Marine Environment Protection Committee (MEPC) has accelerated the pace of formulating energy-saving emission reduction standards for ships in the maritime industry. At present, the IMO is discussing and the forthcoming convention involves the shipbuilding energy-saving emission reduction and efficiency increase mainly include the ship energy efficiency design index (EEDI), the nitrogen oxide Tiern standard and the target shipbuilding standard (GBS).
Once these green ship energy saving and emission reduction targets and relevant regulations are issued, for new ships, the original ship type and design concept will be greatly changed, and many new requirements will also be put forward for marine steel products. Therefore, in the future, steel companies must strengthen their research on new types of steel for ships, including: research and application of light composite plates for ships, application of composite materials, application of polyurethane elastic composite steel (SPS), and corrosion-resistant steel for ships. Applied research, application research of ultra-high strength steels, research on the application scope of high-strength steels, and research on lightening of innovative green ship hull structures.
Marine steel needs to break through
"Mid-term and Long-term Development Plan for Ocean Engineering Equipment Manufacturing Industry" explicitly states that it is necessary to develop marine engineering equipment and implement marine strategies to cultivate new economic growth points for China's shipbuilding industry. By 2015, the international market share of marine engineering equipment in China will reach 20%. .
At present, in addition to domestic steel products used for offshore platform jackets, the steel used in other offshore components is mainly imported. In the future, we must vigorously develop the ocean engineering equipment industry. Our steel companies are to independently research and develop marine engineering steels, including large offshore oil platforms and offshore floating oil storage vessels. The comprehensive mechanical performance required to meet the Z-direction performance requirements is also to be 120 mm. The above high-strength steel sheets, rack steels with a yield strength of 690 MPa or more, and stainless steel pipes and fittings used in marine engineering equipment, deep-water mooring chains for marine engineering, and riser systems are required.
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