With the leaping progress of polymer material technology, the development and utilization of plastic pipe is also deepening. In the past two decades, China's plastic pipe village development, research and production and promotion have achieved significant results. Nowadays, has developed plastic pipes can be used for water supply pipeline project has UPVC pipe, PE pipe, PB pipe, PEX pipe, PP-C pipe, PP-R pipe and metal - plastic composite pipe. The nature of these pipe tree materials are not the same, the production process has its own characteristics, the main scope of application are also different, but the application of water supply pipeline project its light weight, easy to transport and installation, pipe wall smooth resistance coefficient is small, good corrosion resistance, water quality does not constitute a secondary pollution but are **** through. This paper synthesizes the relevant information on the current market commonly used in water supply pipeline project of new plastic pipe tree material properties, production standards and production processes, application scope, etc. for some introduction, for peer reference.
One, hard polyvinyl chloride pipe (UPVC) pipe
Hard PVC pipe is the dominant product of the current domestic plastic pipe. UPVC water supply pipe fittings in 1983 included in the country's "Seven. Five" scientific and technological research projects, after more than a decade of technological development and application practice, both in the production of products or in the actual engineering applications, have accumulated a lot of theoretical and practical experience.
1, material S4 nature and production process of hard polychlorinated ethylene belongs to thermoplastics, its manufactured UPVC pipe material is light, density of 1350 (n1460k8/m3 (steel 7800kg/m3), Vicat softening temperature of 86 ℃, tensile, flexural, compressive strength is high, but the impact strength is relatively low.
UPVC pipe commonly used extrusion molding process, the extruder is divided into single-screw, twin-screw, as far as the extrusion process, double-screw straw extruder is better than single-screw straw extruder.
At present, the domestic production of UPVC pipe more than 400 manufacturers.
2, production standards
Currently the domestic UPVC water supply pipe manufacturers, the vast majority of national standards for the production of pipe, but there are still a considerable number of manufacturers by the introduction of equipment limitations or product exports, the use of British Standard (BS), Japanese Standard (JIS), the German standard (DIN) or IS0 standards for the production of pipe. For users, different standards for the production of pipe, its outer diameter and wall thickness are different, which must be noted in the selection. China's UPVC water supply pipe design, construction, acceptance procedures expressly provided for the selection of pipe must be produced in accordance with China's national standards.
China in 1988 developed a national standard for UPVC water supply pipe GB10002.1-88, 96 years of revision of the standard, promulgated a new national standard GB/T10002.1-1996, non-equivalent to the adoption of the IS04422: 1990 international standards. Pipe fittings standard GB10002.1-88 is now being revised. According to the current national pipe standards, pipe caliber diameter (OD) 20mm to the diameter of alcoholism 0mm *** 28 diameter specifications, pressure level 0.6Mpaol1.6Mpa, *** 5 levels.
According to the experience of many domestic water companies, outdoor UPVC pipeline should be selected pressure class 1.0Mpa. UPVC water supply pipe design, construction, acceptance procedures for the caliber classification of 20mm "630mm, and the caliber classification of the national standard of the pipe was deleted, in order to facilitate the water supply enterprises to prepare for the preparation of materials.
3, connection, fittings
UPVC water supply pipe connection and fittings has been an important factor restricting its application in the project. After more than 10 years of application practice, pipe connection technology and the development of fittings have made great strides in development and progress.
At present, the domestic production of flexible interfaces with a caliber greater than or equal to 63mm (R-R) pipe, caliber below 63mm can also be used to connect the flexible living joints. It can be said that the bonding interface (T-S) mode will gradually be replaced by flexible interface mode, which is the general trend. Fittings, the early 90's handmade fittings have been basically eliminated, in recent years, manufacturers have produced the use of adhesive connection of tees, elbows, etc., but also the use of steel-plastic fittings instead of. 99 years in April, Jiangsu, a factory has been successfully developed a flexible interface of the full plasticization of the tee, elbows and other fittings, caliber 100mm, 150mm, 200mm three kinds of basic to meet the needs of community UPVC water supply Piping project needs.
4, the scope of application
UPVC water supply pipe is mainly used for outdoor buried water supply pipeline, the domestic water statistics show that the selection of caliber more in 250mm and below. In the building water supply (indoor water supply) UPVC pipe is also applied, but the effect is not ideal. In recent years, with the rise of polypropylene, polybutylene, cross-linked polyethylene, aluminum-plastic composite pipe, UPVC pipe will quickly talk about the field of building water supply projects.
Two, polyethylene pipe (PE pipe)
Polyethylene pipe in the gas pipeline project for many years, there are successful theoretical and practical experience. In recent years, there are also a large number of applications in rural water supply projects. A large number of foreign applications in the municipal buried water supply pipe, several domestic enterprises have been committed to the development of this research work, 'overall is still in the initial stage.
1, material 94 properties and production process
Polyethylene is also a thermoplastic, can be molded many times.
Density is one of the important performance indicators of polyethylene, high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE) points. The higher the density, the higher the relative hardness, softening temperature, tensile strength, but increased brittleness, decreased flexibility, decreased resistance to cracking ability. High-density polyethylene is generally used for water supply piping, and high-density and medium-density polyethylene is generally used for gas piping.
High-density polyethylene density 950kg / m 'lighter than UPVC, the softening temperature of 120 ℃ higher than UPVC pipe. Its flexibility, impact resistance are higher than the UPVC pipe, the connection is superior to the UPVC pipe can basically ensure that the connection does not leak (is the body connection). In addition, polyethylene itself is a non-toxic plastic. Europe and the United States the amount of HDPE water supply pipe increases year by year, the amount of UPVC pipe decreases year by year. The general view is that in the water supply piping project, HDPE pipe will eventually replace the UPVC pipe.
Polyethylene pipe village with UPVC pipe, commonly used extrusion molding production process, pipe fittings using injection molding production process.
At present, the domestic production of polyethylene pipe village manufacturers about more than 10 or so, in terms of technical conditions and production capacity, Hebei Yaday Plastic Products Company Limited, Shandong Shengli Plastic Company session of the leading enterprises.
2, production standards
China in 92 years promulgated the water supply with high density polyethylene (HDPE) pipe national standards GB/T13663-13664-92, is now being revised, the revised draft has been submitted to the State Bureau of Technical Supervision.
The current national standards, caliber 16mm to 315mm **** 18 levels, pressure level 0.25Mpaoo1.0Mpa **** 4 levels.
3, connection, fittings
Polyethylene at a temperature of 190 ℃ n 240 ℃ will be melted, the use of this feature, the pipe (or fittings) two melted part of the full contact, and maintain the appropriate pressure, the two will be able to solidly fused into one after cooling. Therefore, the connection of PE pipe is different from UPVC pipe, usually using electric fusion connection and heat fusion butt two ways.
Electrothermal fusion connection is to be connected to the two ends of the insertion of buried electric wire casing, the electric wire energized, to be connected to the pipe, pipe fittings heated to the melting temperature, fixed until the interface cooled, thus forming a tight and solid joints.
Hot fusion butt joint is perpendicular to the pipe axis of the two corresponding end and the heating plate contact to the melting temperature, the two melting port compression connection. Heat fusion butt joints are suitable for pipes with a caliber greater than 90mm.
PE pipe and metal pipe connection, you can use steel-plastic transition joints.
PE pipe manufacturers have developed a variety of specifications of injection molded fittings, special fittings can also be handmade by welding.
4, the scope of application
PE pipe is suitable for outdoor buried water supply pipelines, but also for indoor water supply pipelines. In general, to the current stage of engineering practice is not much. Compared with UPVC pipe, there is no perfect design, construction, acceptance procedures to comply with, which is also the promotion of the application of PE water supply pipe is facing a major problem.
In fact, in addition to UPVC water supply pipe, the existing variety of other plastic water supply pipe are no perfect design, construction, acceptance procedures, in addition to UPVC, PE pipe, and even no national standards for pipe. Similar to the early development and application of UPVC pipe, the tireless efforts of various plastic pipe manufacturers will also promote the technical progress in the field of water supply pipe, promote the development of the industry.
PE pipe can be applied to the old pipe renovation, foreign countries have been widely used, the domestic Dalian also began pilot applications. Third, polybutylene pipe (Yang tube)
Polybutylene is also a thermoplastic, from which the production of PB pipe, is currently the world's most advanced hot and cold water, heating pipe one.
1. Material properties and production process
Polybutylene odorless, non-toxic, high temperature resistance performance is good, the material is flexible and at the same time has good tensile and compressive strength, softening temperature of 121 ℃.
PB pipe density of 930kg / m:, similar to PE pipe.
2, production standards
Currently there are not many domestic manufacturers of PB pipe. Guangdong Foshan, Wuhan has introduced production lines to produce PB pipe. China has not yet formulated the national standards of PB pipe, the production company's corporate standards are generally equivalent to the introduction of the production line of the country's national standards, such as Foshan, Guangdong, a factory is the production of British standards according to BS7291.
PB pipe caliber (outside diameter) of the existing domestic 10mm, 15mm, 22mm, 28mm four specifications, foreign caliber to l10mm PB pipe.
PB pipe pressure capacity and the wall thickness of the pipe, and through the medium - water temperature, especially the temperature of the medium should be specified to the manufacturer when ordering.
3, connection, fittings
PB pipe can be mechanically clamped (insertion) connection or hot melt connection. Manufacturers have developed a variety of types of fittings, can basically meet the needs of engineering applications.
4, the scope of application
As mentioned earlier, PB pipe is suitable for indoor hot and cold water supply system. There are no national standards for pipe village and no national standards for design, construction and acceptance.
Four, cross-linked polyethylene (PEX) pipe
Cross-linked polyethylene is in the ordinary polyethylene raw materials to add organic silane joining technology materials, linear molecular structure modified into a three-dimensional crosslinked mesh structure, changes in the molecular structure of ordinary polyethylene, thereby changing its performance.
1, material 94 properties and production process
PEX and PE pipe, non-toxic, odorless, pressure resistance, stability and durability, and its unique temperature resistance (-70 ℃ cnl10 ℃), so that it has become the indoor hot and cold water supply of the recommended pipe.
PEX pipe density 950kg/m3.
PEX pipe production process is based on polyethylene as the base resin, silane as the bonding bridge material, raw materials through a precision metering system, into the specially designed reaction extruder, the vinyl silane and polyethylene one-step completion of grafting and molding, constituting a three-dimensional three-dimensional molecular network. This one-step production process is currently widely used in the international production of variable linkage polyethylene pipe, the domestic introduction of the production line is also a one-step production work***2, production standards
Domestic production of PEX pipe manufacturers are not many, their production technology are introduced from abroad, the standards used are also based on international standards to develop their own corporate standards and reported to the local government for approval.
PEX pipe caliber (outside diameter) of the existing 16M, 20mm, 25mm, 32mm, 40mm, 501m, 63mm7 specifications.
3, connection, fittings
PEX pipe connection between the manufacturer's supporting the provision of copper connectors and fastening ring, reject the clamp or ferrule type way to connect the PEX pipe and other metal piping connection, the use of special external threaded clamp or ferrule type connecting fittings.
4, the scope of application
PEX is suitable for indoor hot and cold water supply piping. The working pressure of the system is equal to 0.6Mpa, and the long-term working temperature is less than or equal to 75℃ (Building Water Supply and Drainage Code).
Shanghai engineering construction standardization office at the end of 98 issued a recommended local application standards "building water supply crosslinked polyethylene (PEX) pipeline engineering technical specifications", covering the design of PEX pipe, construction, acceptance of three aspects.
Five, polypropylene **** polymer PP-R, PP-C pipe
Polypropylene is colorless, odorless, non-toxic with white waxy particles of material, with excellent heat resistance and high strength, but low melt viscosity, there are low-temperature brittleness defects, it must be modified to meet the needs of pipe production. Currently commonly used modification method is to make PE and PP (polypropylene) in the molecular chain level **** polymerization, the product is called polypropylene **** polymerization, the production of pipelines in the production of raw materials, processing, waste disposal process will not cause harm to human beings and the environment, and therefore is known as the green tree.
Currently, the domestic market PP pipe tree has PP-C, PP-R two kinds, are PP and PE **** polymer. The difference between the two is: ① PP-C, its polyethylene content of 7 (nll ground; ② PP-R, polyethylene content of 3 (n5%; ② PP-C wall thickness is thinner than the same specifications of PP-R; ④ according to the current German classification, PP PP-C is the second generation (type II), PP-R is the third generation (type III); ⑥ PP-R impact resistance is better than PP-C. PP-C, PP-R physical and chemical properties, the scope of application is basically the same. PP-C, PP-R physical and chemical properties, applications are basically the same, so the following is only introduced
Three types of polypropylene (PP-R).
1, material 94 properties and production process
PP-R non-toxic, hygienic, recyclable. PP-R Vicat softening temperature of 131 ° C, the maximum operating temperature of 95 ° C, the long-term use of the temperature of 70 ° C, is a heat-resistant, heat preservation and energy-saving products. Its density 900k8/m:.
PP-R pipes are produced by extrusion molding process, PP-R pipe fittings are produced by injection molding process.
2, production standards
Currently, the country has not yet formulated a unified national pipe standards. PP-R production lines are mostly introduced from Germany, PP-C production lines are mostly introduced from South Korea. Manufacturers mostly refer to the German standard to develop their own corporate standards.
PP-R production specifications from 20mm to 95mm a variety of pipe diameter categories.
3, connection and fittings
PP-R pipe and fittings between the use of heat fusion connection. PP-R and metal fittings connection, the use of polypropylene fittings with metal inserts as a transition, the fittings and PP-R using heat fusion connection, and metal pipes using The fittings are connected with PP-R by heat fusion, and with metal pipe by wire fastening.
4, the scope of application
PP-R pipe is suitable for building indoor hot and cold water supply system, also widely used in heating systems. Europe in the building hot and cold water supply system, the use of PP-R is more common, has risen to become the leading product.
Jilin Provincial Department of Construction, Jilin Provincial Bureau of Technical Supervision in July 98 issued a local standard in Jilin Province, "modified polypropylene (PP-C) radiant floor heating, building water supply and hot water supply technical standards (for trial implementation). Shanghai Engineering Construction Standardization Office in December 1998 issued a recommended local standard "building water supply polypropylene piping (PP-R) engineering technical specifications".
Six, metal-plastic 94 compound table tube
Metal-plastic composite tube is a lot of steel-plastic pipe, copper-plastic pipe, aluminum-plastic pipe, steel skeleton plastic pipe, etc.. Aluminum-plastic composite tube is a new type of rapid development in recent years, this article on the aluminum-plastic composite tube for some introduction.
Material properties and production process
Aluminum-plastic composite tube is an aluminum alloy as the skeleton, aluminum tube inside and outside the plastic tube have a certain thickness. There is a layer of adhesive layer (affinity layer) between the plastic tube and the aluminum tube, which makes the aluminum and plastic combined into one and cannot be peeled off.
Currently used in aluminum-plastic composite pipe plastic are almost all PE pipe, PE pipe is divided into HDPE or PEX. HDPE or general-purpose aluminum-plastic composite pipe, for water temperature stem 40 ℃; PEX said inside and outside of the crosslinked polyethylene aluminum-plastic composite pipe, for water temperature stem 75 ℃.
Aluminum-plastic composite pipe outside the genus polyethylene thickness of not less than 0.4mm, the inner layer of polyethylene is not less than 0.8mm (2 times the thickness of the outer layer), the thickness of the aluminum tape 0.2oo0.25mm. glued layer of the adhesive used (hot melt adhesive) is mainly used **** polymethylene modified polyethylene or chemically grafted polyethylene.
Aluminum-plastic composite pipe has good metal properties and non-metallic properties.
Aluminum-plastic composite tube production of the existing two processes: *** extrusion composite, step-by-step embedded. *** extrusion composite is inside and outside the plastic (including hot melt adhesive) and aluminum tube extrusion molding, generally applicable to the caliber of 32mm below the pipe c step-by-step composite by extruding plastic tube. Extrusion of internal rubber a wrapped aluminum tube an extrusion of external rubber an extrusion of external plastic tube step-by-step process, applicable to the caliber of more than 32mm pipe.
Domestic has now developed a similar to give **** extrusion composite aluminum-plastic composite tube production equipment.
2, production standards
At present, there is no Chinese national standard for aluminum-plastic composite pipe. The current situation is that manufacturers refer to foreign standards to develop their own corporate standards for production.
Aluminum-plastic composite pipe caliber of the current specifications are mostly in the following 100mm (outer diameter), its specifications code and other plastic pipe is slightly different, such as specifications "2025" refers to the inner diameter of the pipe 20mm, the pipe outer diameter of 25mm, the pipe wall thickness of 2.5mm.
3, the connection mode and fittings
Aluminum-plastic composite pipe can be finished coil packaging. Pipes and fittings shall be connected using the manufacturer's special connectors. Different manufacturers to provide special connectors of the connection method and principle are not the same.
4, the scope of application
Aluminum-plastic composite pipe is suitable for hot and cold water supply system in buildings, as mentioned above, general-purpose aluminum-plastic composite pipe for cold water supply, inside and outside the crosslinked polyethylene aluminum-plastic composite pipe for hot water supply.
The country has not yet formulated the design, construction and acceptance specifications for this type of pipe. In recent years, Guangdong, Shanghai and other pipe manufacturers with the relevant design and research units to the local government submitted the aluminum-plastic pipe engineering specifications.
Seven, other plastic pipes
At present, the new varieties of plastic pipes continue to appear. The following other plastic pipes launched in recent years to make some brief introduction.
1, fiberglass reinforced plastic pipe (FRP pipe)
Fiberglass reinforced plastic pipe is a thermosetting plastic pipe, 1950 in the United States, research success, 1955, and gradually used in municipal water supply projects.
FRP pipe is currently produced by two processes: centrifugal casting molding method (H0BAS) and fiber winding method (VER0C). Domestic production of FRP pipe manufacturers at present more, such as Beijing North Star, Zhejiang East (the introduction of H0BAS equipment and technology), Hebei Zhongyi (Veroc) and so on.
Fiberglass reinforced plastic pipe is lightweight (about l / 2 of the steel pipe, high pressure capacity, smooth inner wall, corrosion resistance, easy construction and installation, but the price is higher than the steel pipe (about 1.5 times). It is reported that the United Kingdom, Italy, large-caliber water supply pipes using FRP pipe accounted for 40%, Sweden, Norway accounted for 50%, Japan accounted for 25%. Domestic Beijing has used FRP pipe more than 60km (caliber 600 - 900mm), Daqing use of FRP pipe nearly 20km (caliber 621 - 800mm), Shenzhen Port raw water pipeline 2200mm is also used in FRP Pipe.
2, impact-resistant UPVC pipe (Hl-3P)
Impact-resistant UPVC pipe is the existing UPVC pipe through physical and chemical treatment, the formation of a high-density rigid center layer and impact-resistant inside and outside the three-layer structure of the genus of rigid to improve the low-temperature impact of the ordinary UPVC pipe resistance to low-temperature impact strength of the defects, experiments have confirmed that this three-layer structure of the pipe than the cast iron water supply pipe. Experiments have confirmed that this three-layer structure of the pipe has higher impact strength and tensile strength than cast iron water supply pipe.
HI-3P pipe developed by South Korea G0LEE Corporation, has been introduced into the country. Caliber specifications to 16mm to 400mm.
3, steel skeleton plastic composite pipe with steel wire for the reinforcement, plastic (high-density polyethylene HDPE) as a substrate, the use of steel wire spot welded into the network and extrusion of plastic vacuum filling in synchronization, in the production line of continuous film molding.
Steel skeleton plastic composite pipe to overcome the steel pipe pressure resistance is not corrosion-resistant, corrosion-resistant plastic pipe is not pressure-resistant, steel-plastic pipe is easy to delamination and other defects.
Beijing Huachuang Tianyuan company produces steel skeleton plastic composite pipe, caliber 50mm to 500mm
4, lined with plastic aluminum tube
Sichuan Chengdu Kay withdrew from the production of aluminum lining aluminum alloy tube by the aluminum alloy outer and polypropylene inner layer of the composite by mechanical processing. Its performance is similar to the aluminum-plastic composite tube.
VIII, a comparison of various types of plastic pipe
l, the main performance of various types of plastic pipe comparison
2. Comparison of prices of various types of plastic pipe
Nine, health standards
Prepared for the raw materials selected by the plastic pipe, in addition to the UPVC must control the content of the VCM, the other are non-toxic. But how about the health performance of its manufactured products? How to evaluate? This is also the user is more concerned about the problem.
Generally speaking, the current plastic pipe for drinking water quality is no negative impact. For safety reasons, the user in the purchase of pipe tree should require manufacturers to provide relevant test reports. State Bureau of Technical Supervision, the Ministry of Health in October 1998 promulgated the national standard GB / T17219-lg98 "living drinking water transmission and distribution equipment and protective materials for the safety evaluation standards". The standard health requirements are as follows:
1, where contact with drinking water transmission and distribution equipment and protective materials shall not contaminate the water quality, the pipe network must be consistent with the quality of water GB5749-85 requirements.
2, drinking water transmission and distribution equipment and protective materials must be connected to the provisions of the requirements of the immersion test, the test results must be consistent with the requirements set out in the standard.
3, must be mutagenic test, the result should be negative.
4, the production of drinking water transmission and distribution equipment and protective materials need to use food-grade raw materials.
References:
2, Fang Juan Yu "gas (water) with polyethylene pipes" Building Industry Press 1997
3, Luo Hesheng "practical polypropylene" Guangdong Science and Technology Press 1997
4, Luo Hesheng "practical polyethylene" Guangdong Science and Technology Press 1997
5, the National Chemical Building Materials Coordination Group, the Ministry of Construction, Science and Technology Division, "National Symposium on the Promotion and Application of Plastic Pipes Proceedings," 1999
6, He Weihua, "water supply network pipe review" Chengdu Water Supply Company, 1998
7, the relevant national standards and norms
8, the pipe manufacturers to provide samples of information and technical data.
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