Now, with the development of the chemical industry in our country, the application of duplex stainless steel pipes is becoming more and more extensive. The domestic duplex stainless steel pipes are growing at a rate of 10% every year, and they also have great development prospects in petroleum, urea and other industries. The wide application of stainless steel heat exchanger tubes has stimulated the demand for stainless steel heat exchanger tubes in the market and the enthusiasm for investing in high-end stainless steel heat exchanger control tube machines, which has stimulated the market's demand for high-end stainless steel heat exchanger control tube machines.

       The outstanding performance of duplex stainless steel pipes is high yield strength and stress corrosion resistance, excellent weldability, and less sensitivity to welding cold cracks and hot cracks. In Japan, austenitic and ferritic stainless steel welded pipes account for 54% of the market share in piping systems in the petrochemical industry. However, my country's stainless steel welded pipes are mainly used in the decoration field, and the corrosion-resistant welded pipes used in the petrochemical field are basically blank. At present, domestic stainless steel has a certain gap in terms of variety, standard, quantity, quality, etc., no matter in terms of meeting market demand or comparing with the technical level of advanced industrial countries.

       Specific manifestations: In terms of the quantity of products, the output value of ordinary stainless steel materials for general purposes has been balanced with the overall demand of the market. For materials with higher requirements, the production capacity is insufficient, especially for industrial materials with high requirements, such as high-pressure stainless steel boiler tubes and other basic blanks; For stainless steel pipes with high diameter and high requirements, the supply in the market exceeds supply, and the gap is relatively large. For example, stainless steel pipes with large diameters above φ219mm still need to rely on imports to compensate for the shortage. Another example is super-long (greater than 15m) ultra-long passengers, which are rarely produced in China and basically rely on imports; in terms of types, compared with advanced industrial countries, there are few types of stainless steel in my country, and high-tech types are almost blank, such as Duplex steel, Hastelloy, etc. Some special stainless steel tubes with high technical difficulty and high quality requirements, such as heat exchanger tubes for power plant boilers, urea tubes for fertilizer equipment, etc., mainly rely on imports, and some with excellent corrosion resistance Duplex stainless steel pipes are rarely produced in China and basically rely on imports. To adapt to the increasingly widespread promotion and application of duplex stainless steel, the country should strengthen the popularization of duplex stainless steel welding technology and the research and development of supporting welding materials.

One: chemical and petrochemical processing industry

       This category involves a wide range, complex working conditions, and various media. It is also an earlier and more extensive use of duplex stainless steel. Now 200,000 tons, large-scale and multiple sets of small and medium-sized methanol synthesis reactors below 100,000 t use duplex stainless steel for catalyst tubes, large and medium-sized equipment use 2205 steel pipes, and more inlet pipes are used, and small-scale equipment mostly uses 18- 5Mo type domestic steel pipe. In the next 5 years, my country's petrochemical industry will develop rapidly, and large-scale petrochemical projects under construction and proposed to be constructed are spread all over the country. According to the current projects under construction and projects under construction, the annual demand for stainless steel pipes in the petrochemical industry in 2005 is about 16,000 tons . With the improvement of the quality of domestic stainless steel products and the development of special trademark products, the application of stainless steel in China's domestic petrochemical industry will continue to increase in the next five years.

  Two: duplex stainless steel pipe oil and gas industry

       This is one of the main fields of application of duplex stainless steel in foreign countries, and the oil and gas transportation pipeline has been laid for 1000km. Only a small amount is used in the South China Sea Oilfield in China, all of which are imported. In addition, duplex stainless steel welded pipes are considered to be used for the gas-gathering pipelines of the West-to-East Gas Pipeline Project starting from the Tarim Basin in the west, which have been produced and manufactured in China. The oil refining industry is the first department to use domestic duplex stainless steel. In Nanjing, Zhenhai, Tianjin, Jinan and other refining and chemical companies, it is mostly used in the top fabric (or composite plate) of the atmospheric and vacuum distillation tower, tower internals, air coolers and Water cooler, etc., the longest has been used for 20 years. For the production of small-scale duplex stainless steel seamless pipes, the country is already relatively mature, and what needs to be solved urgently at present is the production of larger-scale seamless pipes and welded pipes, and the production process needs to be developed. In addition, how to reduce the price of duplex stainless steel products is also related to the development of domestic duplex stainless steel. Although it is very important to expand the output value and produce marketable products, what cannot be ignored is the use of new technologies and new processes, the use of molybdenum oxide balls instead of metal molybdenum, nickel oxide instead of metal nickel, reducing smelting costs, and promoting the use of duplex stainless steel continuous casting technology. Improve the yield and so on.

Three: Application of duplex stainless steel pipe in chemical fertilizer industry

       The chemical fertilizer industry chooses domestic 0Cr25Ni6Mo3CuN aging-strengthened duplex stainless steel, and uses its wear-resistant and corrosion-resistant properties to use it for internal parts of high-pressure globe valves with various specifications in the main process pipeline of urea equipment, and the effect is good. At present, the CO2 gas stripping method and NH3 gas stripping method used in the production of urea mostly use high-alloy austenitic stainless steel, or even titanium materials. In China, high-chromium duplex stainless steel has been used instead of high-chromium duplex stainless steel for the ammonium pump body of large-scale urea equipment. 316L (urea grade) steel. Since the 1980s, DP-12 (25Cr-7Ni-3Mo containing trace tungsten and copper) has been selected for the three high-pressure equipment in the ACES urea new process developed by Toyo Engineering Corporation of Japan, the methyl ammonium condenser and the high-pressure differentiation tower. -N steel) and R-5 (00Cr25Ni6.5Mo1.5N) duplex stainless steel, the former is used to make stripping tubes, condensation tubes, differentiation tubes and delivery pipes, etc., while the latter is used for the shell of high-pressure equipment. In 2005, the petrochemical industry's annual demand for stainless steel pipes was about 7,800 tons, and it is expected to increase to 9,600 tons in 2010. the

       The national standard for stainless steel has not been revised for more than ten years. When revising the national standard, it is necessary to consider the acceptance and revision of duplex stainless steel. For the 2205 trademark, which accounts for 80% of the output value, foreign countries have specially formulated user inspection specifications for product factory inspection. We should also consider introducing and absorbing, and enriching existing inspection methods and specifications to promote the production and ordering of duplex stainless steel. In addition, vigorously develop the potential market of duplex stainless steel for industrial and civil use (such as construction industry-structure, bridge, concrete steel bars; such as manufacturing industry-containers, storage tanks, chemical tankers, speedboats, tankers; and for example Household equipment—high-level water tanks, electric water heaters, residential water and vapor piping, etc.), and research, development, trial, and promotion of some new types (such as low-nickel and economical duplex stainless steel) that are developed abroad and are suitable for my country’s national conditions (nickel and chromium deficiency). The promotion of duplex stainless steel in my country has a very broad application prospect.