application

Hard PVC pipe and pipe fittings is a rapid growth trend in many PVC products in our country, and is also the biggest consumption variety of plastic pipe. After the publicity and promotion of PVC pipe in our country in recent years, especially the support of relevant national policies, the production and application of PVC pipe has made great development. The production of PVC pipe has accounted for more than 50% of the total production of plastic pipe. It is widely used in many industries, such as industry, construction, agriculture and so on.

The development of PVC pipe

1. Advantages of PVC pipe

In the production of universal resin, PVC resin has the lowest ethylene consumption and the lowest production cost. The ethylene consumption per ton of PVC in domestic production is 0.5314 tons, and the average ethylene consumption per ton of polyethylene is 1.042 tons. The ethylene consumption per ton of PVC resin in China is about 50% less than that of polyethylene. The raw material chlorine gas used in the production of PVC is an important way to balance the production of caustic soda to produce chlorine gas. Caustic soda is a very important raw material essential to the national economy. In addition, from the point of view of plastic products, PVC has good compatibility with various auxiliaries, and a large number of cheap fillers can be added in the production of pipes, so that the production cost is greatly reduced.

Compared with metal pipes, PVC pipe production per cubic meter of PVC and production per cubic meter of steel and aluminum calculation, steel energy consumption is 316KJ/m3, aluminum energy consumption is 619KJ/m3, PVC energy consumption is 70KJ/m3, that is, steel energy consumption is 4.5 times of PVC, aluminum energy consumption is 8.8 times of PVC. And the production of PVC pipe processing energy consumption is only one third of the same caliber metal pipe. At the same time, due to the smooth wall of PVC pipe, no corrosion tumor, high water delivery efficiency, for infusion can save about 20% of electricity.

PVC pipe has good mechanical properties, and has excellent corrosion resistance, light weight in the process of use, convenient installation, do not need maintenance, and the use of steel for public engineering sewer pipe, in the process of use because of easy corrosion, must often coated with paint, high maintenance costs. General construction and public works with metal pipes about 20 years need to be replaced, and the role of good processing of PVC pipes, the service life of as long as 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 than cast iron pipes. The cost of making a conductor tube is 30-33% less than using a metal conductor sleeve. The action of chlorinated polyvinyl chloride (PVC) pipe in cold and hot water, compared with the use of the same size copper pipe cost savings of 23-44%. Therefore, because of the advantages of PVC pipe, countries are actively developing and promoting PVC pipe.

2. Production and consumption of PVC pipe

Since 80 time, our country has introduced different models of PVC pipe extrusion production line thousand. At present, our country UPVC (hard PVC) pipe and pipe fittings production plants have more than 600, total production capacity of 1.1 million tons/year above, there are more than 30 manufacturers with the production scale of 10,000 tons/year, there are more than 60 manufacturers with the scale of 0.5-10,000 tons/year, the production equipment of UPVC pipe and pipe fittings is basically realized domestically produced.

In OUR COUNTRY, PVC PIPE IS early DEVELOPED than PE pipe and PP PIPE, there are many varieties, excellent performance, wide use, occupying an important position in the market. By the end of 1999, there were more than 2000 plastic pipe production lines in China, of which imported equipment accounted for about 15%. The production capacity of various plastic pipes in our country in 1999 was more than 1.65 million tons/year, the actual output of about 1,000,000 tons, of which UPVC pipes accounted for more than 50%.

Over the years, in the world PVC market application, building materials market is the largest, and the fastest increasing speed. In recent years, the American building materials products have accounted for 60% of its total products, 62% in Western Europe, 50% in Japan, but less than 30% in our country, with great room for rise. In building materials products, and mainly to pipe and profile, including building up and down water pipe, agricultural irrigation pipe, gas pipe, crude oil pipe and so on.

The production and application of UPVC pipe in our country begins to get rapid development during the Ninth Five-Year Plan period, which mainly benefits from the government’s strong support and the society’s understanding of UPVC pipe material.

At present, the application of plastic tube in our country has developed greatly not only in quantity but also in varieties and specifications. For example, UPVC pipe has reached more than 90% in the application of drainage in some cities, and the majority of UPVC pipe enterprises have very good benefits in recent years.

During the Tenth Five-Year Plan period, the promotion and application of plastic pipes were mainly UPVC and PE plastic pipes, and other new plastic pipes were vigorously developed. By 2005, in the new construction, reconstruction and expansion projects nationwide, 50% of construction drainage pipes shall adopt plastic pipes, 20% of urban drainage pipes shall adopt plastic pipes, 60% of building water supply, hot water supply and heating pipes shall adopt plastic pipes, 50% of urban water supply pipes (Dn400 or less) shall adopt plastic pipes, 60% of village water supply pipes shall adopt plastic pipes, Urban gas pipeline (medium and low pressure pipe) 50% use plastic pipe, construction wire threading sleeve 80% use plastic pipe. It is expected that the demand for plastic pipes in 2005 will be more than 2 million tons, the vast majority of which are PVC pipes.

In developed countries, the consumption of PVC pipe generally accounts for 70-80% of the plastic pipe market, but Chinese PVC pipe only accounts for about 50% of the total amount of plastic pipe, the development potential of PVC pipe in our country is very huge. The consumption proportion of PVC pipes in developed countries is as follows: water supply pipe accounts for 33%, sewer pipe accounts for 22.3%, sewage pipe accounts for 15.7%, irrigation pipe accounts for 5.2%, gas pipe accounts for 0.8%, other pipe accounts for 22.7%. Among them, the consumption ratio of pipe fittings and pipe is about 1:8.

In the construction market, there are two kinds of PVC pipe used: one is pressure-resistant pipe, and the other is non-pressure pipe. Cast iron pipe and copper pipe used in the past as pressure resistant building materials, not only serious corrosion, but also need frequent maintenance and replacement, high cost. Foreign buildings are now widely used pressure water pipes, hot water supply pipe mostly use PVC pipe. Small-caliber PVC pipe (UPVC pipe, CPVC pipe) has the advantages of low cost, corrosion resistance, and does not require frequent maintenance and replacement. And large diameter PVC pressure pipe (diameter in 100-900mm) instead of cast iron pipe, enhance the small mud pipe, water supply system has good liquidity, corrosion resistance, low weight. Electricity saving, good water quality. The PVC core layer foam non-pressure pipe as indoor sewer pipe and rainwater system pipe, can solve the noise problem of indoor sewer pipe. Public engineering sewage pipe adopts non-pressure PVC pipe, corrosion resistance, not by hydrogen sulfide erosion, long service life, light weight, low installation cost, easy to connect and seal, not easy to break.

In addition, construction wire pipe and underground cable pipe is another PVC pipe market, the current domestic varieties are straight expansion pipe, double wall pipe and single wall bellows.

Agricultural pipe is another broad field of PVC application. Our country belongs to a country lacking of water resources, at present, most farmland in our country is still using soil irrigation, and water waste is very serious. Due to the lack of water, a lot of arable land is not well irrigated and crop yields are low. And with PVC pipe irrigation, can save about 50% water. The use of PVC fixed or semi-fixed irrigation system planting, not only save water, but also improve the yield, equipment corrosion and other advantages, greatly save the cost of irrigation and spraying facilities. At present, there is not a complete county of solid pipe irrigation in our country, most areas of the country still lack basic understanding of pipe irrigation, therefore, increase the publicity and promotion of PVC pipe irrigation in rural areas, its potential is very huge.

3. Some PVC pipes commonly used in China

UPVC tube: The biggest application of UPVC tube is the construction industry. At present, it is widely used in the tap water piping system and residential water pipes in all provinces and cities across the country, and mainly used in the construction industry as drainage pipes, rain pipes and threading pipes. UPVC tube has chemical corrosion resistance, self-extinguishing and flame retardant, good conditioning resistance, smooth inner wall, good electrical performance, but UPVC tube toughness is low, linear expansion coefficient is large, narrow temperature range. Compared with cast iron pipe, the production and use of UPVC pipe can save 55-68% of energy, and compared with galvanized pipe, the production and use of UPVC water supply pipe can save 62-75% of energy, and the price per unit length of the same specification is only half that of galvanized pipe, and the installation cost is 70% lower than galvanized pipe. Using 1 ton of UPVC water supply pipe can replace 12 tons of cast iron pipe. One ton of UPVC bellows can save 25 tons of steel.

Core layer foam tube: Core layer foam tube is a new type of tube with inner and outer layers produced by three-layer co-extrusion process, which is the same as the ordinary UPVC tube. In the middle is a low foam layer with a relative density of 0.7-0.9. Its annular rigidity is 8 times that of the ordinary UPVC tube, and it has good stability and heat insulation when the temperature changes. More suitable for high-rise building drainage system.

Compared with solid wall tube, foam core layer tube can save more than 25% of raw materials, and the inner wall compressive ability is greatly improved. In the inner wall of the core layer foam silencer tube with a number of convex helical lines, water along the inner wall of the tube free continuous spiral flow, forming a column of air in the center of the drain pipe, so that the pressure in the pipe is reduced by 10%, the general capacity is increased by 10 times, the displacement is increased by 6 times, the noise is 30-40db lower than the ordinary UPVC drain pipe.

PVC radial reinforced pipe: The production of this pipe using a special mold and molding follow-up device, is a kind of heavy diameter super reinforced ring glass grain pipe. It is characterized by radial reinforcement on the outer wall of the pipe, which can greatly improve the stiffness and compressive strength of the pipe ring. It is especially suitable for drainage in municipal engineering.

Double-wall bellows: double-wall bellows are made by extruding two concentric tubes at the same time and then welding the outer tube of the bellows onto a copper tube with a smooth inner wall. With smooth inner wall and corrugated outer wall, light weight and high strength, compared with ordinary UPVC tube can save 40-60% of raw materials, mainly used for communication cable pipe, construction exhaust pipe and agricultural drainage pipe.

PVC time-through reinforced pipe: by the inner and outer two layers of plastic extrusion molding, sandwiched with synthetic fiber, good flexibility, can be bent. PVC transparent pipe has good acid resistance, alkali resistance, oil resistance, aging resistance, can replace rubber pipe, and the price is cheap. Widely used in nitrogen, oxygen, carbon monoxide and other gases and water, dilute alkali, oil and other liquids transportation, also can be used as water heater, sprayer, gas cooker conduit.

CPVC pipe: CPVC pipe is a kind of plastic pipe with good heat resistance, which is processed by chlorinated polyvinyl chloride with more than 66% chlorine content. The heat resistant temperature of CPVC pipe is more than 30℃ higher than that of UPVC pipe, and the dimensional stability is improved, and the linear expansion coefficient is reduced. CPVC tube has excellent heat resistance, aging resistance, chemical corrosion resistance, no deformation in boiling water, can be used for hot water, corrosion resistant liquid and gas transportation.