Performance comparison of water supply parts
With the acceleration of China's urbanization process and the enormous pressure of population, resources and environment, in order to ensure the sustainable development of the national economy, the Chinese government has increased investment in urban infrastructure year by year, and the construction of municipal public pipelines has been accelerating. The specifications are constantly enriched, the output is increasing, the quality is constantly improving, especially the plastic tube development is faster, and it has become a hot spot of investment today.
In 1933, the British ICI company first discovered PE. It has been developed that PE is produced by a variety of processes, and a wide range of resins with a variety of structures and characteristics and a variety of uses, has accounted for one-third of the world's synthetic resin production, ranking first. One of the best uses of PE is that it can be used to produce pipes for transporting any medium other than strong acid and alkali. According to foreign data spinning, the annual consumption of PE pipes in the world's water supply pipelines is about 1 million tons. Widely used in water supply, gas transportation, sewage, agricultural irrigation, fine particle solids transportation, and oil, chemical and postal communications.
Type of water supply pipe
In the past, the pipes used for water supply were mainly cast iron pipes. The outdoor mainly uses sand mold cast iron pipe, the interior uses galvanized cast iron pipe, and can be divided into cold (electric) galvanizing and hot galvanizing. China has stipulated that the sand-casting pipe fittings and cold-galvanized cast iron pipes will be eliminated on June 1, 2000, and the use of hot-dip cast iron pipes will be gradually restricted, and aluminum-plastic composite pipes and plastic pipes will be promoted.
Therefore, there are three main types of pipelines currently in use. The first category is metal pipes, such as hot-dip cast iron pipes, steel pipes, stainless steel pipes, etc. The second category is plastic-plastic pipes, such as plastic-coated steel pipes and aluminum-plastic composite pipes. The third category is plastic pipes, such as PP-R (crosslinked polypropylene high density mesh engineering plastics). The state also stipulates that all kinds of pipes and fittings involving drinking water pipelines must be approved by the health department before they can be sold.
Commonly used plastic code and meaning in water supply pipeline:
PP-R cross-linked polypropylene high-density mesh engineering plastic PE high-density polyethylene PP polypropylene PB polybutene PEX cross-linked polyethylene water supply pipeline comprehensive performance requirements: As a water supply pipeline, it is required to be hygienic, safe, energy-saving and convenient. Therefore, testing a pipeline should be investigated from four aspects. That is, hygiene: pipes and fittings must be free from any damage to the human body.
Safety: It has sufficient strength and excellent mechanical properties as well as anti-aging and heat resistance.
Energy saving: the inner wall is smooth, corrosion resistant, low in fluid resistance and good in heat preservation performance. Convenient: connection, construction is convenient, reliable, and has the possibility of promotion and use. If the above four requirements are not met, it will damage the user's physical health and property safety.
Introduction to several water supply pipes:
1. Aluminum-plastic composite pipe Aluminum-plastic composite pipe is the first water supply pipe to replace cast iron pipe. Its basic composition should be five layers, that is, plastic, hot melt adhesive, aluminum alloy, hot melt adhesive and plastic from the inside to the outside. The aluminum-plastic composite pipe has good thermal insulation performance, and the inner and outer walls are not easy to corrode. Because the inner wall is smooth, the resistance to the fluid is small; and because it can be bent at will, the installation and construction are convenient. As a water supply pipe, the aluminum-plastic composite pipe has sufficient strength, but if the lateral force is too large, it will affect the strength, so it should be used for the construction of the pipe or buried in the wall, but it should not be buried in the ground. The connection of the aluminum-plastic composite pipe is ferrule type, so the first one in the construction is to pass the strict pressure test to check whether the connection is firm. The second is to prevent frequent vibration and loose the ferrule. Third, the length should be sufficient to install, so as not to pull off.
2. Plastic copper tube plastic copper tube is made of pure copper (copper) as pipe fittings and covered with PE plastic. From the perspective of comprehensive performance, the plastic copper tube is slightly better than the aluminum-plastic composite tube. For example, the strength is better, the life is longer, and the heat resistance is better. However, the insulation performance is slightly worse. Pure copper has a very high corrosion resistance. After a period of use, a layer of green oxide will appear on the inner surface. But it has little effect on the life, flow, and resistance to the fluid. The patina is not detrimental to human health and has a certain ability to kill bacteria. The installation method of the plastic copper tube is ferrule type and welded type, and the welding type is more reliable.
Copper pipe, stainless steel pipe: In addition to poor insulation performance, other indicators such as strength, life resistance to fluid resistance are good, and should be used as cold water pipe. If used for hot water delivery, insulation jacket should be added. The connection method is mainly ferrule type, and the copper tube can also be welded. Internal plastic galvanized cast iron pipe: It is a layer of plastic on the inner wall of ordinary galvanized pipe, which has the characteristics of corrosion resistance, low resistance and good heat preservation, and has the characteristics of high strength of galvanized pipe itself. This tube is connected by a rib.
Plastic pipe: Plastic pipe can have sufficient strength, longevity, safety and hygiene as long as the material selection meets the requirements of the standard. It is the best insulation performance of all pipes. The plastic pipe is hot-melt welded, and the reliability is high. As long as the construction is correct, the pipe welding at the normal pressure test will not leak and fall off.
The "National Chemical Building Materials Industry "10th Five-Year Plan" and the 2010 Development Plan Outline pointed out that the promotion and application of plastic pipes mainly consists of UPV-C and PE pipes. By 2005, in the process of new construction, reconstruction and expansion in the country, 70% of the building drainage pipelines use plastic pipes 50% plastic pipes, 60% of the building water supply, hot water supply and heating pipes use plastic pipes, and 50% of urban water supply pipes use plastic pipes. Pipes, 70% of the water supply pipes in villages and towns use plastic pipes, 20% of urban gas pipes use plastic pipes, and 80% of wire sheathed pipes use plastic pipes. First, the water supply and drainage system engineering pipe types and technical, economic and other aspects of comparison:
(1) Type of pipeline
Water supply and drainage system engineering mainly includes: polyethylene pipe (PE), steel pipe, spheroidal pipe, gray cast iron pipe, cement pipe, glass fiber reinforced plastic sand pipe, UPV-C pipe and so on.
(1) Polyethylene pipe (PE)
Polyethylene is classified into high density polyethylene (HDPE), medium density polyethylene pipe (MDPE) and low density polyethylene pipe (LDPE) according to its density. Polyethylene pipes can be divided into single-layer solid wall pipes, double-wall corrugated pipes and spiral wound pipes according to different structural forms. Double-wall corrugated pipe and spiral wound pipe are mainly processed by HDPE raw materials, mainly used in urban drainage, single-layer solid wall HDPE is mainly used in urban water supply and urban gas transportation. Single-layer solid-wall MDPE pipe is mainly used in urban gas transportation. Single-layer solid wall LDPE tubes are widely used as agricultural irrigation pipes and industrial ordinary pipes.
(2) FRP sand pipe
The glass fiber reinforced plastic sand pipe is made of short glass fiber centrifugal or long glass fiber winding, and is made by the middle sand sanding process. The pipe wall is slightly thick and the hoop stiffness is large. It can be used as a buried pipe to withstand internal and external pressure. The pipe diameter can be from 500 diameter. ~ 2600 mm in diameter, the glass fiber reinforced plastic sand tube is brittle, only suitable for large diameter, and during the construction process, mechanical collision is prone to dark injury, and the dark injury is not easy to find, affecting the service life.
(3) Rigid polyethylene pipe UPV-C pipe
The UPV-C tube has high impact resistance and chemical resistance. It can be added according to the use requirements, different additives can be added in the process, so that it has the physical and chemical properties to meet different requirements, UPV-C tube has long life, good sealing, etc., but the UPV-C tube in the process There are heavy metal stabilizers, which will gradually ooze out during use and affect the water source.
(4) Steel pipe
The biggest defects of steel pipe are short service life, strong corrosiveness, poor sealing performance, easy leakage, high price, and poor adaptability to uneven surface settlement.
(5) The cost of the spheroidal tube of the spheroidal tube is high, and the average price is 10% to 15% higher than that of the PE tube. If the angle of the connection interface is too large, it may cause leakage.
(6) Gray cast iron pipe gray cast iron pipe has short service life, large friction coefficient, poor sealing performance and easy leakage.
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