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A Review Of The Development Of Stainless Steel Pipes In My Country In The Past 30 Years

Sep 25, 2020

In the past 30 years, my country's stainless steel pipe production technology has made great progress, the output and quality have been greatly improved, the variety has been continuously expanded, and the standards have been further improved. To this end, the China Institute of Steel Research and Strategy organized a special series of reports on the "30 Years of Stainless Steel Pipes in China" for readers.


1. The 30-year development of stainless steel pipes in my country


Throughout the development history of my country's stainless steel pipe for more than 30 years, it can be divided into the following four stages:


The first stage, the early stage of development before the 1990s. The characteristics of this stage are: the number of stainless steel pipe manufacturing enterprises is small, and most of them are in the workshop-type production stage. The representative company at that time was Shanghai Steel No. 5 Plant (now Baosteel Special Steel), which produced stainless steel seamless pipes that mainly met the special needs of the national defense industry.


The second stage, a period of rapid development between the 1990s and 2000. The characteristics of this stage are: stainless steel pipe manufacturing enterprises have sprung up like bamboo shoots after a rain, and Jiuli Group is one of the representatives. During this period, the development of stainless steel pipes is mainly concentrated in quantity. The demand for stainless steel welded pipes and seamless pipes in various industries in the national economy Rapid growth. Shanghai Steel No. 5 Plant and Great Wall Special Steel are the representative enterprises.


The third stage, the high-speed growth period from 2000 to 2008. The characteristics of this stage are: the explosive growth of stainless steel pipe manufacturing enterprises, and the emergence of industry-leading companies with a production capacity of tens of thousands of tons, such as Jiuli, Taiyuan Iron and Steel, ZTE Energy, and Wujin Stainless.


The fourth stage, the professional subdivision stage from 2008 to present. The characteristics of this stage are: the manufacturing of stainless steel pipes has been further specialized, the pipe manufacturing technology has been significantly improved, and a professional manufacturer of special specifications of pipes has emerged.


First, stainless steel seamless pipes are generally produced by extrusion process to improve quality. During the period, Taiyuan Iron and Steel, Baote, Xinxing Casting Pipe introduced 6000 tons of extruders, Jiuli upgraded 4,200 tons of extruders, Baosteel Special Steel also adjusted its product strategy, dismantled the cross-rolling and piercing units, and concentrated on producing high value-added Pressure pipe.


The second is that the production is more specialized, and even companies that take single-type products as absolute products have emerged. Typical representatives are the integrated nuclear forging main pipeline of Yantai Manuer Nuclear Power Equipment Company, and the stainless steel pipe fittings of ZTE Energy, Wujin Stainless Steel and Sanzhou Nuclear Power. During this period, world-class stainless steel pipe manufacturing enterprises emerged, such as Jiuli Special Material, which has an annual production capacity of 100,000 tons of stainless steel pipes. It is one of the few domestic stainless steel welded pipes with the most complete varieties and largest specifications. The production line also has the internationally advanced extrusion process for stainless steel seamless pipe production line, which can produce welded steel pipes of Φ8-3000mm×0.5-80mm, seamless steel pipes of Φ4-730mm×0.5-60mm, and high-alloy, difficult For deformed alloy steel pipes, a production line with an annual output of 5,000 tons is built to match the pipeline. The products are registered and used in more than 50 countries around the world, creating a brand.


2. Changes in my country's stainless steel pipe production capacity


Due to the large number of stainless steel pipe manufacturing companies and the scattered product specifications, the output statistics are very difficult. According to reports, the world's stainless steel pipe production generally accounts for about 10% of the total amount of stainless steel. At present, my country's stainless steel pipe production generally maintains this ratio.


Before the 1990s, affected by the development of the stainless steel industry, my country's stainless steel pipe production remained at a relatively low level. For example, in 1990, my country's stainless steel pipe production was about 50,000 tons. In 2001, the output of stainless steel pipes in my country was about 500,000 tons, 10 times that of ten years ago. Entering the 21st century, ushered in the great development of stainless steel pipes, and the production capacity and output of stainless steel pipes in my country increased sharply. According to incomplete statistics, there are nearly 500 stainless steel seamless steel pipe manufacturers in my country with an annual production capacity of more than 1 million tons. Most of them are small factories with an annual output of only 1,000 tons. less. There are nearly 800 stainless steel welded pipe production lines with an annual production capacity of 2 million tons. From the perspective of industry demand, the oil and gas/petrochemical industry needs about 60,000 tons of stainless steel pipes, the nuclear power industry needs 50,000 tons of stainless steel pipes, the chemical industry needs about 40,000 tons of stainless steel pipes, and the thermal power industry needs about 40,000 tons of stainless steel pipes.


3. Development of the quality of stainless steel pipes in my country


With the development of the stainless steel industry, the variety development of stainless steel pipes in my country has generally gone through the early single austenitic varieties and the current diversified varieties. Before 1990, due to the limitation of stainless steel pipe manufacturing level and process equipment, stainless steel pipe varieties were mainly 304 and 316 austenitic stainless steel types. After the development in 2000, the varieties of stainless steel pipes almost covered most grades of austenitic stainless steel and duplex stainless steel, as well as some grades of martensitic stainless steel and ferritic stainless steel. During this period, in response to the needs of the petrochemical/chemical industry, developed duplex stainless steel pipes represented by the 2205 grade; developed Cr13 super martensitic stainless steel pipes for oil and gas exploration and transportation; developed 446 for seawater power plant heat exchangers High-purity ferritic stainless steel pipes; developed 316LN integral forged pipes for the main pipeline of the third-generation nuclear power primary circuit; developed super 304H, T/P91 pipes for power station boilers; developed 2169 austenitic stainless steel for aviation oil pipelines Pipe.


In recent years, as the domestic industrial scale production of high-purity ferritic stainless steel has become a reality, a large number of high-purity ferritic stainless steel thin-wall welded pipes have appeared. Laser welding is widely used in the production of these products.


As the chemical, fertilizer, petrochemical and other industries have more and more large-diameter (Φ159mm and above) medium and low-pressure pipelines, large-diameter stainless steel welded pipes are gradually replacing imports and are used for special needs. The oil and gas/chemical industry's demand for ultra-long and large-diameter corrosion-resistant stainless steel pipes has promoted the localization of large-diameter stainless steel welded pipes. For example, the introduction of the Jiuli 630 automatic welding unit has changed the current situation of relying on imports for large-diameter stainless steel welded pipes with a length of 12 meters.


Compared with stainless steel welded pipes, stainless steel seamless pipes have higher performance requirements, more specifications, and a wider range of applications. At the same time, the manufacturing difficulty is correspondingly greater. They are mainly used for oil and gas exploration, petrochemical, energy, nuclear power, and aviation. Aerospace, ships and other fields.


stainless steel seamless pipes are involved in many types of steel, product specifications and uses, and the production processes and equipment used are very different. Therefore, the production of stainless steel pipes is very professional and has high technical requirements. In order to achieve the production of high-quality stainless steel pipes, the development trend of stainless steel pipe manufacturing technology includes three main directions: one is to use extrusion technology to develop new high-performance special stainless steel pipes; the other is to strictly require the metallurgical quality of stainless steel pipe billets, mainly super Pure smelting technology; the third is to set up a highly targeted professional production line for production.


The hot extrusion method is the best method for producing high-alloy hard-deformed alloy pipes, and it is also the most convenient method for manufacturing small batches and multiple varieties of complex cross-section profiles. The use of hot extrusion to produce high-alloy pipes has the characteristics of high deformation temperature, large single deformation, and high deformation rate, which is the trend of future development.

Extruded steel pipe production technology is one of the most important and advanced production methods for seamless steel pipes. For steel grades and alloys with low plasticity and difficult to deform and particularly important applications, such as 690 evaporator tubes for nuclear power, G3 oil well tubes, etc., the cross-rolling piercing method cannot be compared. It has greater deformation under three-way compressive stress than other pressure processing methods, can exert the maximum plasticity of metal, and can reach a compression ratio that other units cannot achieve. At present, steel grades and alloys that cannot be produced on units such as continuous tube rolling mills, Pilger mills, three-roll piercing-tube rolling mills, ACCUROLL, etc. can be produced on extruders. The hot extrusion process is especially suitable for the production of stainless steel pipes with high dimensional accuracy and high surface finish. It has great advantages in the manufacture of difficult-to-deform stainless steel pipes such as super austenitic stainless steel and super duplex stainless steel.


From the beginning of the development of special metallurgical technology, purification, solidification structure and defect control have always run through the development of this technology. Along with the above-mentioned requirements, there has been continuous development in the design and control of special metallurgical equipment and computer simulation of the smelting process. Special metallurgical process technology will continue to develop in the direction of high purity, solidification structure and defect control, smelting process automation, cost reduction and environmental friendliness. Purification smelting, including the control and removal of inclusions, the removal of harmful elements (H, O, S), impurity elements and residual elements (As, Sb, Sn, Bi, etc.), and the process of electroslag remelting due to related slag Control technology for the deviation of Al, Ti, Zr head and tail composition caused by gold reaction. Stainless steel pipes have high requirements for materials. In order to ensure that the surface quality of stainless steel pipes after multiple passes of rolling and deformation is free from defects, the grade and category of inclusions in stainless steel must be strictly controlled. For stainless steel pipes with general special requirements, such as aerospace stainless steel pipes, non-metallic inclusions must be strictly controlled below 1.5. In addition, in order to realize the manufacture of high-grade ferritic stainless steel pipes, there are strict requirements on the carbon and nitrogen content in high-chromium ferritic stainless steel, generally requiring C+N≤300ppm.


In terms of specialized production, the manufacture of integrated nuclear power main pipelines and stainless steel pipe fittings is a typical representative. Take the AP1000 main pipe as an example. Its products are straight pipe + elbow + angled nozzle. Traditional craftsmanship can only be manufactured in sections, and finally welded, resulting in the existence of weak areas of the weld. The use of integral forging can effectively avoid welding. In order to realize the overall forging, it is necessary to have a 100-ton electroslag furnace and a press capacity of 8,000 tons or more. In addition, it also involves core technologies such as stainless steel elbow bending technology. The production route of this large-size stainless steel special-shaped pipe is completely different from ordinary stainless steel seamless pipes. To this end, it is necessary to establish a professional nuclear power primary circuit main pipeline production line, and Yantai Manuer Nuclear Power Equipment Company came into being. In addition, the manufacture of a large number of stainless steel pipe fittings for petrochemical/chemical industries requires large-diameter Pilger rolling mills. For this reason, professional manufacturers of stainless steel pipe fittings such as ZTE Energy, Wujin Stainless Steel, and Sanzhou Nuclear Power have emerged. In the future, such subdivided professional stainless steel pipe production lines will appear more and more to improve product quality and production efficiency, including Tiancai Technology (the smallest diameter 0.2mm, the smallest diameter), which mainly produces capillary tubes and small-size stainless steel seamless pipes. The wall thickness is 0.05mm) and Jiuli’s fully automatic and efficient power station boiler tube production line.


4. my country's stainless steel pipe internationalization process


Before 2000, due to the weak overall quality of my country's stainless steel pipes, the products lacked international competitiveness and were rarely exported. The international market for high-end stainless steel pipes has long been occupied by Western developed countries, represented by Sumitomo, Sandvik and Outokumpu. my country needs to import a large number of high-grade stainless steel pipes every year. For example, in 2006, my country's stainless steel pipe imports were about 45,000 tons, which are basically high-grade varieties. After 2005, especially after 2010, with the increasing variety and quality of stainless steel pipes in my country, some high-quality and low-cost stainless steel pipes began to be exported, and the export volume was increasing. The exported products are mainly used in nuclear power, petrochemical, chemical, energy, shipbuilding and other fields.


In recent years, some major international engineering projects have adopted stainless steel pipes produced in my country, including the international scientific research cooperation project "International Thermonuclear Experimental Reactor (ITER) Project", SECCO 900,000 tons of ethylene cracking unit, and Yamba integrated project (600,000 tons of ethylene) and so on.


On the whole, my country's stainless steel pipe exports mainly relied on price advantages in the early days, but now they are all based on quality. As my country has become a major country in stainless steel manufacturing, the production scale and level of stainless steel pipes have gradually ranked in the forefront of the world. The global concept of stainless steel pipe manufacturing enterprises has become stronger and stronger. Enterprises in Jiangsu and Zhejiang provinces are in the forefront of the variety and quantity of stainless steel pipe exports. . Companies obtain a large amount of demand information from industry associations, international conferences, and the Internet, and actively negotiate with foreign companies to obtain orders, and then rely on large and complete stainless steel pipe production lines to provide high-quality products to meet user needs.