Now with the continuous development of the chemical industry in China, use of duplex stainless steel welded pipe is also increasing, the annual demand for Chinese duplex stainless steel tube in the rapid growth, and in the oil, urea and other industries also have a very good development. The main performance of duplex stainless steel tube is high yield strength and good stress corrosion resistance. The welding performance of the duplex stainless steel tube is good, and the sensitivity of welding cold crack and hot crack is low.
In China, stainless steel welded pipe is mainly used in the field of decoration, in the field of petrochemical corrosion resistant welded pipe is relatively less. In terms of variety, specification, quantity and quality, China’s stainless steel has some differences in terms of market demand and technical level compared with advanced industrial countries. Specifically, in the number of products, the common use of ordinary stainless steel has been the basic supply and demand balance. But the high demand materials, the production capacity is not enough, especially the high requirements of industrial materials, such as high pressure stainless steel pot and so on, and a lot worse.
In product specifications, small diameter stainless steel tube for general purpose is oversupply, large aperture and high requirements of stainless steel pipe, the market demand gap is large, such as large diameter stainless steel with 219mm tube above the need to rely on imports to make up for lack of. A super length (greater than 15m) long off, China rarely production, are basically rely on imports; in terms of varieties, compared with advanced countries, China’s stainless steel less varieties, not many varieties of high technical content, such as duplex steel, Hastelloy alloy, stainless steel and special technical difficulty large, high quality requirements, such as heat exchanger tubes, boiler tubes and other devices with urea fertilizer, low yield depends on imports, some with good resistance to corrosion of duplex stainless steel tube, China rarely production, basically rely on imports. In order to adapt to the increasingly widespread application of duplex stainless steel, China should strengthen the popularization of duplex stainless steel welding technology and the development of welding materials.
Chemical and petrochemical processing industry
The field of chemical engineering is the earlier and more important area of using duplex stainless steel. The catalyst tubes for medium and small methanol synthesis reactors are made of duplex stainless steel, large and medium sized units adopt 2205 steel tubes, more imported steel pipes are used, and small scale units are made of 18-5Mo type steel pipes made in china.
The medium condition (HCI, steam) of the cooling coil pipe in the chlorination reactor of Qilu Petrochemical Industries Co’s VCM unit is very harsh. At present, the imported 2205 duplex stainless steel has been used, and the results need to be observed.
The catalyst regeneration cooler of Shanghai Petrochemical Co ethylene plant uses 00C25Ni7Mo3WCuN duplex stainless steel similar to DP3 steel as sea water cooler tube, and the seawater outlet temperature is 40T.
The coolers of pulverized coal gasification plant in Henan coal chemical plant are made of imported 2205 steel pipes.
Petroleum and natural gas industry
This is one of the main applications of duplex stainless steel in foreign countries. For the production of small size duplex stainless steel welded pipe, China has been more mature, but the production process of large size seamless pipe and welded pipe needs to be developed. In addition, how to reduce the price of duplex stainless steel products is also related to the development of China’s duplex stainless steel. Is to expand production and production of marketable marketable products is very important, can not be ignored is to adopt new technology, using spherical molybdenum oxide instead of metal molybdenum, nickel oxide instead of metal nickel, reducing the smelting cost, promote the use of duplex stainless steel casting technology, improve yield rate etc..
The main use of the chemical fertilizer industry China production enhanced duplex stainless steel 0Cr25Ni6Mo3CuN with aging, the wear corrosion resistance, high pressure cut-off valve for the main process of urea plant piping specifications in parts, the effect is good. The production of urea CO2 stripping and NH3 stripping is the high alloy austenitic stainless steel, and titanium, China has adopted high chromium stainless steel to replace 316L in Methylamine Pump on large scale urea plant (urea) steel. Since 80s, the Toyo Project Corporation to develop new technology of ACES urea in stripper, ammonium carbamate condenser and high-pressure decomposition tower three high-pressure devices using the DP-12 (25Cr-7Ni-3Mo-N Steel Containing Trace Tungsten and copper) and R-5 (00Cr25Ni6.5Mo1.5N) duplex stainless steel, the former is used to manufacture gas pipe, condenser tube, tube decomposition and pipelines the latter, housing for high voltage equipment.
Source: China Duplex Stainless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)