application

Rigid PVC pipe, pipe fittings in many PVC products, in our rapid growth trend, is also the biggest consumption of various plastic pipes.  Through the propaganda and promotion of PVC tubing in our country in recent years, especially the support of relevant national policies, the production and application of PVC tubing has made great development, the output of PVC tubing has accounted for more than 50% of the total production of plastic tubing, which is widely used in many industries, industry, construction, agriculture, etc.

1. Development of PVC pipe

1.1 Advantages of PVC pipe

In general resin production, PVC resin consumption is the lowest, production cost is also the lowest.  The ethylene consumption per ton of PVC in China is 0.5314 tons, while 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.  And the production of PVC with raw material chlorine gas, 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 and a variety of additives are good compatibility, in the production of pipes can be added to a large number of cheap fillers, so that the production cost is greatly reduced.

Compared with metal pipes, PVC pipe production per cubic meter PVC and production per cubic meter 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 that of PVC, aluminum energy consumption is 8.8 times that of PVC.  The production of PVC pipe processing energy consumption is only one third of the same diameter metal pipe.  At the same time, because the PVC pipe wall is smooth, no corrosion tumor, high water transmission efficiency, used for transfusion can save about 20% of electricity.

PVC pipe has good mechanical properties, and has excellent corrosion resistance, light weight in the process of use, easy installation, no maintenance, and the use of steel as a public sewer pipe, in the process of use because of easy corrosion, must often coated with paint, high maintenance cost.  General construction and public works with metal pipes need to be replaced for about 20 years, and the role of well-processed PVC pipes, service life of up to 50 years, etc.  Therefore, PVC pipe is a good plastic product with low production cost, high strength and corrosion resistance.

Generally speaking, in terms of sewage, wastewater and ventilation pipes, PVC pipes save about 16-37% of installation and labor costs than the use of cast iron pipes;  The cost of wire pipe is 30-33% less than that of metal wire bushing.  And the role of chlorinated polyvinyl chloride (PVC) pipe in hot and cold 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.

1.2 Production and consumption of PVC pipes

Since THE 1980S, OUR COUNTRY SUCCESSIVELY INTRODUCED DIFFERENT MODELS OF PVC pipe EXTRUSION PRODUCTION LINE OF more THAN ONE THOUSAND, which EMERGED LIKE DALIAN SHIDE, ZHEJIANG YONGGAO, Shanghai TOMCHEN AND OTHER LARGE PIPE PRODUCERS.  At present, there are more than 600 UPVC (hard PVC) pipe and pipe fittings production plants in our country, with a total production capacity of more than 1.1 million tons/year, more than 30 manufacturers with more than 10,000 tons/year production scale, and more than 60 manufacturers with a scale of 0.5-10,000 tons/year, production equipment of UPVC pipe and pipe fittings is basically realized domestically.

In OUR COUNTRY, PVC PIPE IS DEVELOPED EARLIER THAN PE PIPE AND PP PIPE, more varieties, excellent performance, widely used, occupies an important position in the market.  By the end of 1999, there were more than 2000 plastic pipe production lines in China, among which the imported equipment accounted for about 15%.  In 1999, the production capacity of all kinds of plastics tubing in our country exceeded 1.65 million tons/year, the actual production of about 1 million tons, and UPVC tubing accounted for more than 50%.

Over the years, in the world PVC market application, building materials market as the largest, and the fastest increase in speed.  In RECENT YEARS, American BUILDING MATERIALS PRODUCTS ALWAYS TAKE UP 60% OF THEIR TOTAL PRODUCTS, Western Europe 62%, Japan 50%, our proportion is less than 30%, rising room.  In building materials products, and pipe and profile mainly, including building water pipe, agricultural irrigation pipe, gas pipe, crude oil pipe, etc.

The production and application of UPVC pipes in China began to develop rapidly during the Ninth Five-Year Plan period, which mainly benefited from the government’s strong support and society’s understanding of UPVC pipes.

At present, the application of plastic pipe has been greatly developed 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 urban buildings, and most UPVC pipe enterprises have achieved good benefits in recent years.

During the TENTH FIVE-YEAR Plan period, UPVC AND PE PLASTIC PIPES WERE MAINLY used IN THE promotion and application of plastic pipes, and other new plastic pipes were vigorously developed.  By 2005, in the country’s new construction, reconstruction and expansion projects, 50% of the building drainage pipes using plastic pipes, 20% of the urban drainage pipes using plastic pipes, 60% of the building water supply, hot water supply and heating pipes using plastic pipes, urban water supply pipes (Dn400 below) 50% using plastic pipes, 60% of the village water supply pipes using plastic pipes,  50% of urban gas pipes (medium and low pressure pipes) use plastic pipes, and 80% of building wire threading bushing use plastic pipes.  It is estimated that the demand for plastic tubing in 2005 is more than 2 million tons, most of which are PVC tubing.

In the developed country, PVC pipe consumption generally accounts for 70-80% of the plastic pipe market, while PVC pipe in our country only accounts for about 50% of the total amount of plastic pipe, the development potential of PVC pipe in our country is very enormous.  The consumption proportion of PVC pipes in developed countries is: water supply pipes account for 33%, water down pipes account for 22.3%, sewage pipes account for 15.7%, irrigation pipes account for 5.2%, gas pipes account for 0.8%, other pipes account for 22.7%.  The consumption ratio of pipe fitting and pipe is about 1:8.

In the construction market, there are two kinds of PVC pipes used: one is pressure-resistant pipe, one is pressure-free pipe.  Cast iron pipe and copper pipe commonly used in the past as pressure-resistant building materials are not only corroded seriously, but also need frequent maintenance and replacement, with high cost.  Foreign buildings are now widely used pressure water pipe, 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 no need for frequent maintenance and replacement.  And large caliber PVC pressure pipe (diameter in 100-900mm) instead of cast iron pipe, enhance the small mud pipe, water supply system fluidity, corrosion resistance, low weight.  Electricity saving, good water quality.  And the PVC core layer foam pressure free pipe as the indoor water pipe and rainwater system pipe, can solve the noise problem of indoor water pipe.  The utility sewage pipe is made of unpressed PVC pipe, which is corrosion-resistant and not eroded by hydrogen sulfide, has long service life, light weight, low installation cost, easy to connect and seal, and is not easy to break.  In addition, the construction of string pipe and underground cable guard pipe is another market for PVC pipes, currently the varieties used in China are direct expansion pipe, double wall pipe and single wall bellows.

Agricultural pipe is another broad field of PVC application.  Our country is short of resources, at present, most of our farmland is still using canal irrigation, water waste is very serious.  And because of the lack of water, a lot of farmland is not well irrigated, and crop yields are low.  And using PVC pipe for irrigation can save about 50% water.  The use of PVC fixed or semi-fixed irrigation system farming, not only saves water, but also can improve the output, equipment corrosion and other advantages, greatly saving the cost of irrigation and spraying facilities.  At present, our country has not yet a county complete real pipe irrigation, the vast majority of the country still lack the basic understanding of pipe irrigation, therefore, increase the publicity and promotion of PVC pipe irrigation in rural areas, its potential is very huge.

1.3  PVC pipes commonly used in China

UPVC tube: The biggest application of UPVC tube is construction industry.  At present, it is widely used in the water pipe system and residential water pipe in various provinces and cities across the country. It is mainly used as drain pipe, rain pipe and threading pipe in the construction industry.  UPV tube has chemical corrosion resistance, self-extinguishing and flame retardant, good resistance to molding, smooth inner wall, good electrical performance, but the UPVC tube toughness is low, linear expansion coefficient is large, the use of a narrow temperature range.  The development of UPVC pipe has obvious benefits. The production and use of UPVC pipe save 55-68% energy than cast iron pipe, the production and use of UPVC water supply pipe save 62-75% energy than galvanized pipe, and the price of unit length of the same specification is only 1/2 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 foam tube:  Core layer foam pipe is a three layer, a total of extrusion process in the production of inside and outside two layer is the same as ordinary UPVC pipe, the middle is the relative density is 0.7 0.9 low foaming layer of a new type of pipe, the ring to the rigid is 8 times of ordinary UPVC pipe, and the temperature changes when the feet have good stability, good thermal insulation, especially foam core layer can have cut off the noise transmission,  More suitable for high-rise building drainage system.

Compared with solid wall tube, foamed core layer tube can save more than 25% raw material, and the inner wall compressive ability is greatly improved.  And in the inner wall with a number of convex spiral lines in the core layer foam silking pipe, water flow along the inner wall of the pipe freely and continuously in a spiral shape, forming an air column in the middle of the drain pipe, so that the pipe pressure 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 adopts special mold and forming follow-up device, which is a kind of heavy-duty large-caliber super-strong rib ring glass grain pipe.  The outer wall OF the pipe is equipped with radial reinforcement, which can greatly improve the stiffness and compressive strength of the pipe ring, 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 on the copper tube with smooth inner wall.  With smooth inner wall and corrugated outer wall, light weight and high strength, compared with ordinary UPVC pipe can save 40-60% of raw materials, mainly used as communication cable guard pipe, building exhaust pipe and agricultural drainage pipe.

PVC PERMEable reinforced pipe: the inner and outer two layers of plastic extrusion molding and made of synthetic fiber sandwiched in the middle, good flexibility, bending.  PVC transparent pipe has good acid resistance, alkali resistance, oil resistance, aging resistance, can replace rubber pipe, and the price is cheap.  Widely used for nitrogen, oxygen, carbon monoxide and other gases and water, dilute alkali, oil and other liquid transport, can also 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 containing more than 66% chlorine.  The thermal temperature of CPVC tube is more than 30℃ higher than that of UPVC tube, and the dimensional stability is improved, and the linear expansion coefficient is reduced.  The CPVC tube has excellent heat resistance, aging resistance and chemical corrosion resistance, and does not deform in boiling water. It can be used for the transportation of hot water, corrosion-resistant liquids and gases.  Domestic Yunnan Dian-huai Science and Technology Development Co., LTD produces CPVC pipes.