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PVC PIPE SITUATION AND TREND IN CHINA

Rigid PVC pipes and fittings are among the many PVC products, showing a rapid growth trend in China, and are also the most consumed variety of various plastic pipes. After the publicity and promotion of PVC pipes in China in recent years, especially the support of relevant national policies, the production and application of PVC pipes have made great progress. The production of PVC pipes has accounted for more than 50% of the total output of plastic pipes. It is widely used in industry, construction, Agriculture and many other industries.

1 Development situation of PVC pipes

1.1 Advantages of PVC pipes

In general-purpose resin production, PVC resin has the lowest ethylene consumption and the lowest production cost. Domestic production of PVC consumes 0.5314 tons of ethylene per ton, and polyethylene consumes 1.042 tons of ethylene per ton on average. Domestic consumption of ethylene per ton of PVC resin is about 50% less than polyethylene. The raw material chlorine used in the production of PVC is an important way to balance the production of caustic soda to produce chlorine. Caustic soda is an indispensable raw material for the national economy. In addition, from the perspective of plastic products, PVC has good compatibility with various additives, and a large amount of inexpensive fillers can be added to the production of pipes, which greatly reduces the production cost.

Comparing PVC pipes with metal pipes, the production of PVC per cubic meter and the production of steel and aluminum per cubic meter, the energy consumption of steel is 316KJ / m3, the energy consumption of aluminum is 619KJ / m3, the energy consumption of PVC is 70KJ / m3, That is, the energy consumption of steel is 4.5 times that of PVC, and the energy consumption of aluminum is 8.8 times that of PVC. The processing energy consumption of producing PVC pipes is only one third of the same caliber metal pipes. At the same time, due to the smoothness of the PVC pipe wall, no corrosion tumors, and high water transfer efficiency, it can save about 20% electricity for infusion.

PVC pipe has good mechanical properties and excellent corrosion resistance. It is light in use and easy to install and requires no maintenance. The use of steel for sewage pipes in public works must be corroded during use. Frequent application of paints results in high maintenance costs. Metal pipes for general construction and public works need to be replaced in about 20 years, and PVC pipes with good processing have a service life of up to 50 years. Therefore, PVC pipe is a good plastic product with low production cost, high strength and corrosion resistance.

Generally speaking, in terms of sewage, waste water and ventilation pipes, PVC pipes save about 16-37% of installation and labor costs compared to the use of cast iron pipes; the use of wire pipes saves 30-33% of the costs compared to the use of metal wire sleeves; In terms of cold and hot water, polyvinyl chloride (PVC) pipes save 23-44% of the cost compared to using copper pipes of the same size. Therefore, due to the advantages of PVC pipes, countries are actively developing and promoting PVC pipes.

1.2 Production and consumption of PVC pipes

Since the 1980s, China has introduced thousands of different types of PVC pipe extrusion production lines, and large pipe manufacturers such as Dalian Shide, Zhejiang Yonggao and Shanghai Tomson have emerged. At present, there are more than 600 UPVC (hard PVC) pipes and fittings production plants in China, with a total production capacity of 1.1 million tons / year and more than 30 manufacturers with a production scale of 10,000 tons / year and over 0.5-1 There are more than 60 manufacturers of 10,000 tons / year, and the production equipment of UPVC pipes and fittings has basically been domestically produced.

In China, PVC pipes are developed earlier than PE pipes and PP pipes. They have many varieties, excellent performance, and are widely used. They occupy an important position in the market. By the end of 1999, there were more than 2,000 plastic pipe production lines nationwide, of which about 15% were imported equipment. In 1999, the production capacity of various plastic pipes in China exceeded 1.65 million tons per year, and the actual output was about 1 million tons, of which UPVC pipes accounted for more than 50%.

In these years, in the world PVC market application, the building materials market is the largest, and the growth rate is also the fastest. In recent years, building materials products in the United States have accounted for 60% of its total products, 62% in Western Europe, 50% in Japan, and less than 30% in China. Among the building materials products, it is mainly made of pipes and profiles, including building water pipes, agricultural irrigation pipes, gas delivery pipes, crude oil delivery pipes, etc.

The production and application of UPVC pipes in China really began to develop rapidly during the "Ninth Five-Year Plan" period, mainly due to the strong support of the government and the society's understanding of UPVC pipes.

At present, the application of plastic pipes in China has been greatly developed not only in quantity but also in varieties and specifications. For example, UPVC pipes have reached more than 90% in some urban building drainage applications, and most UPVC pipe companies have achieved very good results in recent years.

During the "Tenth Five-Year Plan" period, the popularization and application of plastic pipes were mainly UPVC and PE plastic pipes, and other new types of plastic pipes were vigorously developed. By 2005, in the national new construction, reconstruction, and expansion projects, 50% of the construction drainage pipes will use plastic pipes, 20% of the urban drainage pipes will use plastic pipes, and 60% of the building water supply, hot water supply and heating pipes will use plastic pipes. Plastic pipes are used for 50% of pipelines (below Dn400), plastic pipes for 60% of village and town water supply pipelines, plastic pipes for 50% of urban gas pipelines (medium and low pressure pipes), and 80% of construction wire threading sheath pipes. It is estimated that the demand for plastic pipes will exceed 2 million tons in 2005, most of which are PVC pipes.

In developed countries, PVC pipe consumption generally accounts for 70-80% of the plastic pipe market, while China's PVC pipe only accounts for about 50% of the total plastic pipe. China's PVC pipe has great potential for development. The consumption ratio of PVC pipes in developed countries is: water supply pipes account for 33%, sewer pipes account for 22.3%, sewage pipes account for 15.7%, irrigation pipes account for 5.2%, gas pipes account for 0.8%, and other pipes account for 22.7%. The consumption ratio of pipe fittings and pipe materials is about 1: 8.

In the construction market, there are two types of PVC pipes: one is pressure-resistant pipe and the other is pressure-free pipe. The cast iron pipes and copper pipes generally used in the past as pressure-resistant building materials not only have serious corrosion, but also require frequent maintenance and replacement, and the cost is relatively high. PVC pipes are now widely used in foreign constructions for pressure-resistant water pipes and hot water supply pipes. Small-caliber PVC pipes (UPVC pipes, CPVC pipes) have the advantages of low cost, corrosion resistance, and do not require frequent maintenance and replacement. The large-diameter PVC pressure pipe (diameter 100-900mm) replaces cast iron pipes and reinforced small mud pipes. The water supply system has good fluidity, corrosion resistance and low weight. Power saving and good water quality. The use of PVC core layer foam pressureless pipes as indoor sewer pipes and rainwater system pipes can well solve the noise problem of indoor sewer pipes. The public engineering sewage pipe adopts pressureless PVC pipe, which is corrosion-resistant, free from hydrogen sulfide, long service life, light weight, low installation cost, easy to connect and seal, and not easy to break. In addition, string pipes and underground cable protection pipes for construction are another market for PVC pipes. The varieties currently used in China are straight expansion pipes, double-wall pipes and single-wall corrugated pipes.

Agricultural pipes are another broad field of PVC applications. China is a country that lacks water resources. At present, most of the farmland in our country is still irrigated with earth channels, and water is wasted very seriously. Due to lack of water, a large amount of cultivated land is not well irrigated and crop yields are low. And irrigation with PVC pipes can save about 50% of water. The use of PVC fixed or semi-fixed irrigation systems for farming not only saves water, but also improves output and the equipment does not corrode, which greatly saves the cost of irrigation and sprinkling facilities. At present, there is no county in China that has fully implemented pipe irrigation, and most of the country lacks basic knowledge of pipe irrigation. Therefore, the potential for increasing the promotion and promotion of PVC pipe irrigation in rural areas is huge.

1.3 Some PVC pipes commonly used in China

UPVC pipe: The biggest application of UPVC pipe is in the construction industry. At present, it is popularized and applied in the water pipe system and residential water pipes of various provinces and cities in the country, and is mainly used as drainage pipes, rain pipes and threading pipes in the construction industry. UPV pipe has chemical resistance, self-extinguishment and flame retardancy, good chemical resistance, smooth inner wall, good electrical performance, but UPVC pipe has low toughness, large linear expansion coefficient, and narrow temperature range. The benefits of developing UPVC pipes are obvious. The production and use of UPVC pipes is 55-68% more energy-efficient than cast iron pipes. The production and use of UPVC water pipes is 62-75% more energy-efficient than galvanized pipes. The price per unit length of the same specification is only 1/1 of galvanized pipes 2. The installation cost is 70% lower than that of galvanized pipe. The use of 1 ton UPVC water supply pipe can replace 12 ton cast iron pipe. The application of 1 ton UPVC corrugated pipe can save 25 tons of steel.

Core layer foam tube: The core layer foam tube is the same as the ordinary UPVC tube produced by the three-layer co-extrusion process, and the middle is a new type of pipe with a low foam layer with a relative density of 0.7-0.9. The rigidity is 8 times that of ordinary UPVC pipes, and the stability of the ruler is good when the temperature changes, and the heat insulation is good. Especially the foam core layer can cross the noise transmission, which is more suitable for the drainage system of high-rise buildings.

Foam core tube can save more than 25% of raw materials compared with solid wall tube, and the inner wall compression resistance is greatly improved. In the inner wall with a number of convex spiral core foam muffler pipes, water flows freely and continuously in a spiral shape along the inner wall of the pipe. An air column is formed in the center of the drain pipe to reduce the pressure in the pipe by 10% and increase the general capacity by 10 times. The displacement is increased by 6 times, and the noise is 30-40db lower than that of ordinary UPVC drainage pipes.
PVC radial reinforced pipe: This kind of pipe is produced with special molds and forming follow-up devices. It is a heavy-duty large-caliber super-strength ring-shaped glass pipe. The characteristic is that the outer wall of the pipe is provided with radial reinforcing ribs, which can greatly improve the rigidity and compressive strength of the pipe ring, and is especially suitable for drainage in municipal engineering.

Double-wall corrugated pipe: Double-wall corrugated pipe is made by extruding two concentric pipes at the same time, and then welding the outer pipe of the corrugated pipe to the copper pipe with smooth inner wall. It has a smooth inner wall and a corrugated outer wall. It is light in weight and high in strength. It can save 40-60% of raw materials than ordinary UPVC pipes. It is mainly used for communication cable protection pipes, building exhaust pipes and agricultural drainage pipes.

PVC permeable reinforced pipe: It is made by extruding two layers of plastic inside and outside, with synthetic fibers in the middle, which has good flexibility and can be bent. PVC transparent pipe has good acid resistance, alkali resistance, oil resistance, aging resistance, can replace rubber pipes, and the price is cheap. It is widely used in the transportation of gases such as nitrogen, oxygen, carbon monoxide, and liquids such as water, dilute alkali, oil, etc. It can also be used as a conduit for water heaters, sprayers, gas stoves, etc.

CPVC pipe: CPVC pipe is a kind of plastic pipe with good heat resistance which is processed from chlorinated polyvinyl chloride with chlorine content up to 66%. The heat resistance temperature of CPVC pipe is higher than UPVC pipe by more than 30 ℃, and the dimensional stability is improved and the linear expansion coefficient is reduced. CPVC pipes are excellent in heat resistance, aging resistance and chemical resistance, and are not deformed in boiling water. They can be used for the transportation of hot water, corrosion-resistant liquids and gases. Domestic Youli Co., Ltd. produces CPVC pipes.

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