Production equipment of stainless steel pipe
Sharp tools make good work. For production-oriented enterprises, equipment is undoubtedly the lifeblood of an enterprise. The quality of the equipment determines the product quality and performance, and also determines the future operation of the enterprise.
Common equipment in stainless steel pipe enterprises
Stainless steel pipe is usually divided into seamless pipe and welded pipe. And in the production process, the required equipment is not the same. The difference can be seen from the two production process flow chart.
Fig.1 production process flow of seamless pipe
The above figure shows the production process of seamless pipe. It can be seen that perforation, cold drawing (cold rolling) and detection are the key links in the whole process. Correspondingly, piercer, drawing mill, rolling mill and all kinds of testing equipment play an important role in the whole production process.
The common ones include Φ 50, Φ 90 and Φ 250 series hot-rolled piercing mills. The Φ 2000mm Julong piercing mill can pass through the solid billet with diameter of 210-1000mm, and can also pass through the hollow tube billet with diameter of 1000-2000mm twice. The rolling specification of the mill is second to none in the world, which has played a great role in promoting the development of seamless steel pipe production equipment in China and even in the world and the market progress of large caliber seamless steel pipe. The other type of tzc200 cone roll piercing mill adopts combined frame, cone roll piercing, full hydraulic quick roll change and digital display numerical control feed angle adjustment technology, which is in the domestic leading level and reaches the contemporary international level. It has been used in some large stainless steel plants in China.
In the process of pipe making and forming, cold drawing and cold rolling are two coexisting processes. The effect achieved in actual production is the same, and the seamless pipe produced has its own advantages. At present, among the stainless steel pipe making enterprises in China, ylb100t, ylb150t, ylb250t and ylb550t series high-precision hydraulic cold drawing units are more commonly used and have good reputation. Among the cold rolling mills, lg30-h, lg55-h, lg60-h, lg60-2h, lg110-h, lg250-h series cold rolling tube mills are more widely used. Lg-200 and φ 159 tandem mills are also preferred by some large steel mills. Among them, lg-200 cold rolling pipe mill can roll seamless steel pipe of φ 125-200×3.5-22×4000-10000, and φ 159 continuous pipe mill can roll seamless steel pipe with diameter of 114-159.
Fig. 2 production process flow chart of stainless steel welded pipe
The above figure shows the production process flow chart of stainless steel welded pipe. The forming and welding are the main processes for the plate (strip) to turn into a round pipe. In the welding process, the most common welding equipment are straight seam high-frequency welding equipment, straight seam double-sided welding process and spiral submerged arc welding process. Mu-25m, mu-32m, mu-57m, mu-76m, mu-159m, mu-325m series automatic welded pipe units are also common equipment in welded pipe manufacturers.
Production capacity and equipment status of steel pipe enterprises in China
According to incomplete statistics, China’s stainless steel seamless pipe production capacity reached 876000 tons in 2007, and the welded pipe production capacity reached 948000 tons. From our understanding of the expansion of enterprises, some large enterprises began to expand part of the project in 2007. By 2008, the production capacity of seamless pipe will be increased by 100000 tons, and that of welded pipe will be increased by nearly 40000 tons. But judging from the actual situation this year, except for some expansion projects which started construction last year or even earlier, there are not many new projects this year. On the one hand, the steel pipe market this year is affected by the economic environment and downstream demand, which appears to be a bit sluggish. On the other hand, the tightening of national capital lending has increased, making some enterprises lack funds for expansion plans Support, and then the impact of global demand and domestic policies, exports are not very smooth. Under multiple pressures, most of the expansion plans of enterprises have been delayed. Enterprise equipment updates have also decreased.
In the steel pipe industry, the share of enterprises of different sizes is pyramid – the number of large-scale enterprises is very small, and the small-scale enterprises occupy a considerable proportion. From a certain point of view, such industrial structure also affects the overall level of industrial equipment to a certain extent. For most of the products, the productivity of the products is relatively low due to the low efficiency of production. In addition, the enterprise’s technological level update speed is slow, which makes the enterprise’s products lack of obvious advantages in quality and competitiveness in the market.
The market competition is so fierce that enterprises must change the status quo and achieve breakthrough if they want to develop forward. The role of equipment for enterprises is the same as that of weapons for troops. Advanced equipment can improve the production efficiency, save labor costs, improve product quality, and comprehensively enhance the competitiveness of enterprises. More and more enterprises recognize this point and are cautious in introducing new equipment.
In addition to grasp the production process through production equipment, the internal inspection of product quality is also particularly important. In the past, the old-fashioned production enterprises basically guaranteed the pipe drawing machine, rolling mill, pipe welding machine and pickling equipment, but the quality inspection equipment seemed dispensable. Only some large-scale enterprises or enterprises mainly exporting would purchase them. However, with the increasing number of enterprises, the number of similar products in the market is also gradually increasing, “winning by quality” has become a magic weapon for products to stand out in the competition. Enterprises pay more and more attention to product quality inspection, especially in some newly-built factories. Enterprises strive to put all equipment in place at one time, and testing equipment has become an indispensable “quality controller” in enterprises. Eddy current testing, ultrasonic testing, hydraulic testing machine and other testing equipment have been very common in enterprises.
Production process of seamless pipe
Advanced equipment is a prerequisite for the smooth development of an enterprise. If there is a good craft to add fuel to the flames, we can get twice the result with half the effort. In the production process of seamless pipe, hot rolling, cold rolling and cold drawing are the main production methods.
Hot rolled seamless pipe is usually produced on the automatic pipe mill. It is called hot rolling, which actually includes the process of heating and piercing the solid tube blank. The hollow tube blank is formed after piercing and then rolled on the pipe rolling mill. It is an advanced method to produce hot rolled seamless steel tube by continuous pipe mill. However, this process is not very practical for the enterprises which purchase hollow tube blank for further processing.
In the cold drawing process, a welding head is welded on one end of the tube blank, and then it is drawn on a 0.5-100t single chain or double chain cold drawing machine. Cold rolling is usually carried out on a two high mill. The steel tube is rolled in the annular pass composed of variable cross-section circular groove and fixed conical plug. For most seamless pipe manufacturers, most of the tube blanks are not self-produced, but purchased from outside. Hot rolling process is difficult to achieve, and cold drawing and cold rolling process forms have become their first choice. Although the same seamless pipe production process, but the way is different, the product quality is also slightly different. Cold drawing equipment line is widely used in small enterprises, and the wall thickness of cold-rolled pipe is uniform, the inner surface is smoother and the yield is high.
Of course, the combination of cold rolling and cold drawing can produce seamless tubes with smaller size and better quality. But “pull before rolling” and “rolling after rolling” are two different combination ways.
In the process of the combination of drawing and rolling in the past, the sequence of first drawing and then rolling was mainly used. The stainless steel industrial pipe is directly produced by the tube drawing machine process, and then the cold-rolled industrial pipe is produced through the rolling mill process. Although the wall thickness of the pipe produced by this method is more uniform, the cost is relatively high, which is not acceptable to the general customers, and it is also quite difficult for the enterprise to apply it.
Recently, the way of rolling first and then pulling is becoming familiar to people. After the stainless steel tube blank passes through the rolling mill process, the stainless steel industrial pipe produced by the pipe drawing machine not only has uniform wall thickness and beautiful appearance, but also greatly shortens the production cycle. The production cost is similar to the traditional industrial pipe, which is about 2000 yuan cheaper than the traditional cold-rolled industrial pipe. At the same time, the product also has the characteristics of cold-rolled industrial pipe. To achieve the real sense of good quality and low price.
Advanced technology and mature process also need good equipment to cooperate, in order to achieve more perfect production process. The complementary relationship between process and equipment is self-evident. Just like two chopsticks, only by cooperating with each other can the greatest effect be achieved.
Source: China Stainless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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