Original Title: Overview of Development of Titanium and Titanium Alloy Longitudinal Welded Pipe in China Review on Development of Titanium and Titanium Alloy Longitudinal Welded Pipe in China Abstract: In this paper, the development course, application, production technology and product standard of titanium and titanium alloy longitudinal welded pipe in China are introduced and commented in detail, and the future development trend is predicted. This paper introduces the current production process of a single 6m long titanium and titanium alloy straight welded pipe. The titanium welded pipe produced by this process not only ensures the uniform wall thickness, but also reduces the splicing circumferential weld in pipeline installation. It fills in the domestic blank of big bore single 6m long titanium and titanium alloy straight welded pipe production. This paper points out that the product standard of big bore titanium and titanium alloy welded pipe has not been formulated and issued so far, which has a certain impact on the development of big bore titanium and titanium alloy welded pipe industry. Introduction Along with that development of industrial technology and the introduction of new technology in our country, the problem of pipeline corrosion is a very serious destructive factor that affect the development of modern industry. Pipeline corrosion in industrial and chemical enterprises cause running, emitting, dripping and leak, which not only affects the normal production, but also reduces the product quality, pollutes the environment, wastes energy and increases the probability of security risks. The long-term existence of the above problems has seriously hindered the progress of China's industrialization. Therefore, the emergence of a pipeline with the characteristics of corrosion resistance, high strength, wear resistance, low cost, low pollution and easy maintenance is imperative. Titanium and titanium alloy longitudinal welded pipe (hereinafter referred to as "titanium welded pipe") has high strength, light weight, good heat transfer and corrosion resistance, as a substitute for steel and stainless steel pipes, and the use of big bore titanium welded pipe in industrial pipelines has also been recognized by the market. Although that investment cost of the titanium weld pipe is higher than that of a common fluid transmission pipeline, the cost of the titanium weld pipe is lower than that of a titanium seamless pipe by about 15 to 25 percent And that service life of the pipeline is prolon to reduce the production cost. Up to now, titanium has been widely used in chemical, petroleum, petrochemical, vacuum salt, pharmaceutical, desalination, power and other industries. In particular, titanium can better resist the erosion of chloride ions, so titanium materials are widely used in chlorine-related media. For example, titanium materials have been widely used in manufacturing equipment, pipelines and pipe fittings in the production of ion-exchange membrane caustic soda. In addition, titanium pipelines are used to transport media in formic acid, acetic acid, propylene oxide and other chemical projects to solve the problem of pipeline corrosion and prolong the service life of pipelines. In the titanium pipe,titanium plate gr7, the chemical composition, mechanical properties and process performance of titanium welded pipe and titanium seamless pipe are basically the same.However, titanium welded pipe has the advantages that titanium seamless pipe does not have in practical application.Titanium welded pipe can achieve big bore and ultra-large diameter flow transmission.In addition, the economy and applicability of titanium welded pipe are easier to be promoted and used. As a relatively unique form of titanium pipe product, titanium welded pipe is a kind of product which is made by rolling titanium plate or titanium coil into pipe shape and then using tungsten inert gas welding to weld the gap. Because of its excellent corrosion resistance and high specific strength, it has attracted wide attention and use in the industrial field since its development. At present, small bore titanium welded tubes (nominal size DN100 and below) have been used in various condensers and heat exchangers to gradually replace titanium seamless tubes as the preferred material for heat exchange tubes, while big bore titanium welded tubes (nominal size DN100 and above) are also widely used as industrial pipelines in chemical, petroleum, petrochemical, salt making, pharmaceutical and marine engineering industries. Expand the full text I. Development Course of Titanium Welded Pipe in China In the early days of the founding of the People's Republic of China, titanium was only used in the military industry and belonged to the national strategic control materials. It was not until the 1970s that titanium was used in the chemical field of civil industry. So far, it has a history of more than 40 years. As an excellent corrosion-resistant structural material,titanium plate gr7, titanium has established its irreplaceable position. As an ideal material for transporting corrosive media in chemical pipelines, Titanium welded pipe has also attracted more and more attention and use of equipment and pipeline designers. 1. Working condition of titanium welded pipe As we all know, titanium welded pipe is often used in corrosive environment because of its excellent characteristics. When the liquid with corrosive medium flows through the titanium welded pipe, the corrosive medium will cause weak erosion and corrosion on the inner wall of the welded pipe. With the difference of medium and its concentration, the corrosion degree of titanium welded pipe is also different. In general, the corrosion rate of high concentration medium is greater than that of low concentration under the same medium, the corrosion rate of boiling medium is greater than that of room temperature, the corrosion rates of halogen-containing medium are greater than those of other salt solutions, and the corrosion rates of titanium materials with high inner wall bearing pressure are greater than those of titanium materials with low inner wall bearing pressure under the same wall thickness and medium. Therefore, the service life of titanium welded pipe mainly depends on the corrosive medium in contact with it, the use environment and the bearing pressure. 2. Development Process of Titanium Welded Pipe Due to the constraints of raw materials and processing technology, the production technology of titanium welded pipe has been in the hands of professional manufacturers in Japan, the United States, France, Russia and a few other countries for many years. Therefore, compared with other titanium processing products, China's titanium welded pipe started late and developed slowly in the early stage, which directly affected the standardization of titanium welded pipe products. So far, the national standard of titanium welded pipe is not perfect. China began to develop titanium welded pipes in the 1980s. In 1985, the former Baoji Nonferrous Metal Processing Plant (now Baoji Titanium Group Co., Ltd.) Introduced China's first complete automatic production line of small bore titanium welded pipes from the United States, ending the history that China could not produce titanium welded pipes. However, due to the multiple effects of technology introduction and digestion and difficulties in purchasing raw materials, the production line did not really have production capacity until the end of the 1990s, with an annual capacity of only about 200 tons. In the mid-1990s, Changzhou, Titanium welding pipe ,6al4v titanium bar, China and Valtimet Company of France jointly established Falinuo Great Wall Welded Pipe Co., Ltd. and introduced three small bore welded pipe production lines to produce titanium welded pipes. However, most of the raw materials in the early stage were imported from Japan and the United States due to the poor production technology of titanium coils in China. Limited by quality and output, the domestic titanium welded pipe market had not really formed at that time. With the breakthrough of domestic titanium strip production technology, Xi'an Baotai Meitefalinuo Welded Pipe Co., Ltd. has successfully realized mass production by adopting the cold-rolled strip produced by Baotai Group, and the welding technology of thick-walled titanium welded pipe developed by it has filled the gap of domestic welded pipe production technology. At the same time, the use of titanium strip coil in Baotai Group also fills in the blank of domestic titanium strip production of titanium welded pipe. At the beginning of this century, with the appearance of the problems such as leakage, dripping and dripping caused by corrosion in industrial pipelines, the demand for corrosion-resistant big bore titanium welded pipes in industrial pipeline systems is increasing day by day. Some titanium equipment manufacturers use rolling method to produce short big bore titanium welded pipe (single length is not more than 3 meters), but because of the immaturity of production technology, there are problems such as small production, low productivity, unstable product quality and unfavorable installation. 3. Brief Introduction to Production Process of small bore Titanium Longitudinal Welded Pipe The processing of small bore titanium welded pipe is based on titanium strip coil as raw material, which is extruded on special roller continuous forming machine after uncoiling, and the final product is completed on the whole production line. The method is continuous production, and has the advantages of large production capacity, high productivity, good molding quality, labor saving and the like. Among them, there are many forming methods of roller continuous forming machine, and the titanium welded pipe is mostly formed by W bending method. 4. Brief Introduction to Production Process of big bore Titanium Longitudinal Welded Pipe The production of domestic big bore titanium welded pipe is limited by technical level and market demand, and the intermittent production process is mostly used. The production raw material adopts a titanium coil or a titanium wide plate, and the titanium coil or the titanium wide plate is pressed and formed by special equipment. There are several forming methods for big bore titanium welded pipe forming equipment. For titanium welded pipe, the commonly used methods are single-radius bending deformation method and multi-radius bending deformation method. Compared with the single-radius bending deformation method, the multi-radius bending deformation method is not limited in the forming diameter, and the single-radius bending formation method is only applicable to the outer diameter size of a standard pipe and is not applicable to the production of a non-standard pipe. At present, the demand for big bore titanium welded pipe in China is still relatively low, which is related to its production cost, production technology and product standardization. 5. Application of Titanium Welded Pipe Titanium welded pipe was first used in aerospace field because of its extremely high specific strength, which can not only reduce the weight of aircraft, but also prolong the service life and reduce maintenance time. At the beginning of this century, the civil market of titanium materials and products was formed, and titanium welded pipes were widely used in petrochemical, salt making, pharmaceutical and other industries because of their excellent corrosion resistance and thermal conductivity. With the rapid development of modern industry, the natural environment and water resources have been greatly polluted, so that copper and copper alloy pipes and stainless steel pipes, which have excellent performance in pure water and clean seawater, are prone to serious corrosion leakage, so titanium welded pipes as a substitute for other metal materials are also used in seawater desalination equipment. Although the price of titanium welded pipe is slightly higher, the service life of the whole titanium pipe is greatly improved, the maintenance cost of shutdown is reduced, and the environmental pollution is small, which meets the overall requirements of building a conservation-oriented and environment-friendly society. II. Brief Description of Standards and Specifications for Titanium Welded Pipe in China The production technology of titanium welded pipe in China develops slowly and starts late, so the standards and specifications of titanium welded pipe are still developing and improving. In 1984, the national standards GB4367-84 Welded and Welded-Rolled Titanium Tubes and GB4368-84 Welded-Rolled Titanium Tubes for Heat Exchangers and Condensers were compiled by the former Baoji Nonferrous Metal Processing Plant and approved by the State Bureau of Technical Supervision. . This standard has been implemented for nearly In the past 11 years, it has guided and standardized the production and manufacture of small bore titanium welded pipes at that time. The promulgation of these two standards represents the beginning of the standardization of small bore titanium welded pipes in China, and is the main reference document for the production, distribution, design and construction of titanium welded pipes in China. With the development and maturity of titanium welded pipe manufacturing technology, in order to make the standard better and more effectively guide the production and manufacture of titanium welded pipe in China. In October 1995, China revised and issued the national standards GB/T 3624-1995 Titanium and Titanium Alloy Tubes (replacing GB 4367-84) and GB/T Titanium and Titanium Alloy Tubes for Heat Exchangers and Condensers (replacing GB 4368-84). These two standards effectively merge titanium seamless pipe and titanium welded pipe into one standard, which represents that the production and manufacture of small bore titanium seamless pipe and titanium welded pipe in China has entered a normal level of development. III. Prospect of Titanium Welded Pipe At present, the application of titanium in civil industry accounts for more than 80% of the total titanium consumption in China. In the Twelfth Five-Year Plan, the state has increased the investment and reconstruction of energy, chemical industry, marine engineering and other projects. It is planned that the equipment of petroleum, chemical industry, synthetic fiber, salt making, alkali making, marine engineering and other industries in China is in a new period of development, renewal and transformation. In the past, petroleum and chemical equipment mostly used ordinary steel or stainless steel, and the equipment structure was obsolete, which affected the quality of products. Most of the anticorrosive materials used in new modern devices are required to have strong corrosion resistance, such as sodium ions and chloride ions in ionic membrane caustic soda devices, which have strong acidity and alkalinity after being separated by ionic membrane method or diaphragm method, and the temperature is about 80 ℃. It is difficult to resist the corrosion of the medium when pipes are made of ordinary steel and stainless steel materials. Therefore, a large number of titanium materials are used to replace steel or stainless steel materials to make electrolytic cells, separators, containers, pipes, pipe fittings and pump valves at home and abroad, and good use value and economic benefits are obtained. About 300 to 500 tons of titanium materials are used in the caustic soda plant with an annual output of 1 million tons, including 60 to 100 tons of titanium pipe fittings. The titanium welded pipe will also gradually expand the scope of application, such as offshore platforms, desalination plants and saline cooling devices in power plants and other corrosive media pipeline transportation. Because of the high cost of titanium, there are certain restrictions on the wide application of titanium welded pipes. In order to reduce the cost of titanium pipes,titanium seamless tube, some domestic manufacturers have successfully developed titanium/steel composite pipes (base pipe material is steel, lining or inner cladding material is titanium) with reference to SY6623-2005 "Bimetal Composite Pipe". The cost of titanium/steel composite pipe is 30 ~ 50% less than that of titanium pipe, and composite pipe will be the development direction of anti-corrosion pipeline in the future. Contact us Back to Sohu to see more Responsible Editor:. yunchtitanium.com