One is the stainless steel seamless pipe extrusion process to improve the quality. During the period, Tisco, treasure, xinxing ductile iron pipes imported 6000 tons of extrusion press, jiuli upgraded 4200 tons of extrusion press, Baosteel special steel products strategic adjustment, demolition of piercing mill units, concentrated production of high value-added extruded pipes. 

Second, the production is more specialized, even the enterprise with the single product as the absolute product, the typical representative such as Yantai mah nuclear power equipment company's nuclear power overall forging manager road, ZTE energy, Wujin stainless steel, three continents nuclear energy stainless steel pipe fittings and so on. During this period, the world-class stainless steel pipe manufacturing enterprises, such as jiuli, with an annual production capacity of 100 thousand tons of stainless steel pipes, are the only stainless steel welded pipe production lines with the highest range of the varieties, specifications and the international advanced extrusion technology, can produce the Φ 8 - 3000 mm× 0.5 - 80 mm welded steel pipes and the specification for the seamless steel tubes with φ 4 - 730 0.5 - 60, and the alloy steel tubes with high alloy and hard deformation, and have a production line with an annual output of 5,000 tons per year. Products in more than 50 countries in the world registered trademarks and use, made the brand. 

2. The change of production capacity of stainless steel tube in China
Stainless steel tube because of the manufacturing enterprises dispersed, product specifications are numerous, so the production statistics is very difficult. It is reported that the production of stainless steel tubes in the world generally accounts for about 10 % of total stainless steel. At present, the output of stainless steel tube in our country maintains this proportion. 

Before the 1990s, the output of stainless steel tube was kept at a low level, such as the output of stainless steel pipe in China was about 50 thousand tons in 1990. In 2001, the output of stainless steel tubes in China was about 500,000 tons, 10 times that of ten years ago. Enter the 21st century, ushered in the development of stainless steel tube, the production capacity and output of stainless steel tube in our country sharply increased. According to incomplete statistics, the existing stainless steel seamless steel pipe production enterprises in China nearly 500, annual production capacity of more than 100 million tons, most of which is a small factory with an annual output of less than 1000 tons, the annual output of more than 10,000 tons of enterprises is very few. Stainless steel welded pipe production line nearly 800, annual production capacity of 200 million tons. According to the industry demand, the annual stainless steel pipe of oil / gas / petrochemical industry is about 60 thousand tons, the nuclear power industry needs 50 thousand tons of stainless steel pipe, the annual stainless steel pipe of the chemical industry is about 40 thousand tons, and the thermal power industry needs about 40 thousand tons of stainless steel pipe.

3. Development of quality of stainless steel tube in China
With the development of stainless steel industry, the variety development of stainless steel tube in our country has experienced the early single austenitic variety and the present variety stage. Before 1990, due to the limitation of the manufacturing level and process equipment of stainless steel pipe, the stainless steel pipe varieties were mainly 304 and 316 austenitic stainless steel types. After the development of 2000, the stainless steel pipe varieties almost cover the majority of austenitic stainless steel, duplex stainless steel, and martensitic stainless steel and ferritic stainless steel parts. During this period, the 2205 duplex stainless steel pipe was developed for petrochemical / chemical industry demand. For the exploitation and transportation of oil and gas, the super martensitic stainless steel pipe with cr13 type was developed. 446 high - purity ferritic stainless steel pipes were developed for the heat exchanger of sea hydropower station. According to the main circuit of the third generation nuclear power circuit, the whole forging pipe of 316 is developed. Super 304 and t / P91 pipes have been developed for power plant boilers. The 2169 austenitic stainless steel pipe was developed for the aviation oil pipeline. 

In recent years, with the domestic industrial scale production of high purity ferritic stainless steel become a reality, a large number of high purity ferritic stainless steel thin - walled welded pipe appears. These products are widely used in the production of laser welding. 

With the demand of chemical, chemical fertilizer, petrochemical and other industries to the large diameter ( Φ 159 ) low pressure pipeline, the large diameter stainless steel welded pipe gradually replaces the import, and applies to the special needs. The demand of oil / gas / chemical for super long and large diameter corrosion resistant stainless steel pipe has promoted the localization of large diameter stainless steel welded pipe, such as the introduction of jiuli automatic welding machine, and changed the status of the 12 - meter large diameter stainless steel welded pipe relying on import. 

Compared with stainless steel welded pipe, the stainless steel seamless pipe has higher performance requirements, more requirements, wider use of the field, and the manufacturing of a lot of difficulties, mainly for oil and gas exploration, petrochemical, energy, nuclear power, aerospace, naval ships and other fields.

Because of the many kinds of steel, product specifications and uses of stainless steel seamless pipe, the production process and equipment are very different, so the production of stainless steel pipe is very strong, the technical requirements are high. In order to realize the production of high quality stainless steel pipe, the development trend of the manufacturing technology of stainless steel pipe includes three main directions: one is to develop new high performance special stainless steel pipe by extrusion technology; The second is to strictly require the metallurgical quality of stainless steel tube, mainly UP smelting technology; Third, the establishment of a strong professional production line for production. 

Hot extrusion is the best way to produce high alloy difficult alloy pipes, and it is also the most convenient method for the manufacture of small batch and multi - varieties. The production of high alloy pipe by hot extrusion has the characteristics of high deformation temperature, large deformation rate and high deformation rate, which is the trend of future development. 

The extrusion steel pipe production technology is one of the most important and advanced production methods of seamless steel pipe. For the low plastic refractory steel and alloy and especially important applications, such as nuclear power 690 evaporator tube, G3 oil well pipe, etc., is not comparable to the oblique piercing method. It is more than other pressure processing method has a greater three - dimensional stress state of deformation, can play the maximum plastic metal, can achieve the other units can not achieve the compression ratio. At present, steel grades and alloys that cannot be produced on such units as the MPM plant, the pil unit, the three - roll perforated - pipe mill, accu - roll, etc. can be produced on the extruder. Hot extrusion process for the production of high dimensional precision, high surface finish of stainless steel pipe is particularly suitable for super austenitic stainless steel, super duplex stainless steel and other difficult deformation stainless steel pipe manufacturing has a greater advantage. 

From the beginning of the development of special metallurgical technology, the development of the technology is always running through the purity, solidification structure and defect control. With the above requirements, the design and control of special metallurgical equipment and the computer simulation of smelting process are continuously developed. The future of special metallurgical technology will continue to develop along the direction of high purity, solidification structure and defect control, automation of smelting process, low cost and friendly environment. Pure smelting, including inclusion control and removal, the removal of harmful elements (H, O, S ) and impurity elements and residual elements ( As, Sb, Sn, Bi, etc. ), as well as the control technology of Al, Ti, Zr and head to tail components deviation caused by the relevant slag gold reaction during ESR process. The requirement of stainless steel pipe material is very high. in order to ensure the surface quality of stainless steel pipe after multi-pass rolling, the inclusion grade and category of stainless steel must be strictly controlled. General special requirements of stainless steel pipes, such as aerospace stainless steel tubes, its non-metallic inclusions shall be strictly controlled below 1.5 level. In addition, in order to realize the manufacture of high grade ferritic stainless steel pipe, the content of carbon and nitrogen in high chromium ferritic stainless steel is strictly required, and the general requirement of c + n ≤ 300 ppm.

In the field of specialized production, the nuclear power integration manager road and stainless steel pipe fittings manufacturing are typical representatives. Take ap1000 main channel as an example, its products are straight pipe + elbow + angle tube mouth. The traditional technology can only be made in section, and finally welded, resulting in the existence of weak zone. The whole forging system can effectively avoid welding. In order to achieve the overall forging, there must be 100 tons of ESR furnace and more than 8000 tons of press capacity, in addition, also involves the stainless steel elbow bending technology and other core technology. This kind of large - size stainless steel tube, the production line is completely different from the ordinary stainless steel seamless pipe. Therefore, it is necessary to establish a professional nuclear power primary circuit pipeline production line, Yantai Nur nuclear power equipment company came into being. In addition, the large number of stainless steel pipe fittings in petrochemical / chemical industry requires large caliber pil mill. To this end, the emergence of ZTE energy, Wujin stainless steel, three continents nuclear power and other professional manufacturers of stainless steel pipe fittings. The future of this kind of subdivision stainless steel pipe professional production line will be more and more, to improve the product quality and production efficiency, including the production of capillary and small stainless steel seamless pipe - based technology ( minimum diameter of 0.2 mm, minimum wall thickness of 0.05 mm ) and jiuli automatic and efficient power plant boiler tube production line. 

4. The process of internationalization of stainless steel pipe in China
Before 2000, due to the weak overall quality of the stainless steel tubes in China, the products lack international competitiveness and few exports. The international market of high - end stainless steel pipes is occupied by western developed countries, and is represented by sumitomo, Sandvik and Otto. China needs to import a large number of high-grade stainless steel tubes every year, such as in 2006, China's stainless steel pipe imports of about 4.5 million tons, basically are high-grade varieties. After 2005, especially after 2010, with the more and more varieties of stainless steel pipes in China, the quality of stainless steel tubes is higher and higher, some of the stainless steel pipes with high quality and low price start to export, and the export volume is more and more large. Export products are mainly used in nuclear power, petrochemical, chemical, energy, ships and other fields. 

In recent years, some international major projects have adopted the production of stainless steel pipes, including international scientific research cooperation projects " international thermonuclear fusion experimental reactor ( ITER ) program ", match million tons of ethylene cracking joint plant, BASF-YPC integration project ( 600,000 tons of ethylene ), and so on. 

Overall, China's stainless steel pipe exports, early mainly rely on the price advantage, now is the quality of victory. With China has become a large manufacturing country of stainless steel, the production scale and level of stainless steel pipe is also gradually in the forefront of the world, the global concept of stainless steel pipe manufacturing enterprises is more and more strong, the enterprises in Jiangsu and Zhejiang provinces, stainless steel pipe exports and the number of the forefront. Enterprises obtain a large number of demand information from the industry associations, international conferences, internet and other ways, and actively negotiate with foreign enterprises, obtain orders, and then rely on large and complete stainless steel tube production line, to provide high-quality products to meet the needs of users.