Current status and development of pvc and pe pipes
Since the early 1980s, the state has vigorously promoted the application of upvc pipes, and has formulated a series of policies, systems, and standards, and accumulated a lot of experience. Up to today, we have already established a complete product standard, testing method standards and testing methods, construction engineering technical specifications, etc., so that the same product size and quality indicators, to achieve product interchangeability. This shows that the development of pvc water supply pipeline has entered a mature stage, and the product quality and construction quality are guaranteed, thus ensuring the use of pvc water supply pipeline.
The international standard for water supply pe pipes (ISO4427) was not officially released until 1996. In 1999, China compiled the national standard GB/T13663 with reference to ISO4427, and it was released and implemented in 2000. However, the standards and engineering specifications of pe pipe fittings are still being improved. This shows that the quality of domestic pe pipe is not stable, and the pipe fittings are not perfect, so the quality in production and construction cannot be ensured.
Comparison of mechanical properties of two kinds of pipes
Strength comparison of materials at room temperature
The short-term and long-term strength of pvc materials are much higher than that of pe materials.
Comparison of minimum required strength (MRS) and safety factor (C)
Both theoretical and practical experience show that the MRS and safety factor of pvc are much higher than pe, that is, the strength and safety of long-term use are higher than pe. Therefore, the same 75mm pipe material, pvc material is much thinner than the pipe material produced by pe material. This is because the strength and long-term strength of pe material are not as high as pvc at room temperature, and the strength can only be increased by increasing the wall thickness. If the same wall thickness is taken, the pe tube does not reach the required strength. If the same pipe diameter is taken, the pvc pipe can have a larger water delivery path than the pe pipe. On the other hand, if the same amount of water is to be reached, a larger diameter pe tube is required, and the engineering cost is significantly increased. It shows that the higher strength and rigidity of the pvc material is economical as a water supply pipe.
Life comparison
Polyvinyl chloride (pvc) is a polar macromolecule that is more stable than monomeric vinyl chloride (pe) and some small molecules, so it is less susceptible to environmental influences. However, the emergence of crosslinked vinyl chloride and other polymers will now improve in this respect.
Hygienic performance comparison
Both pvc and pe are environmentally friendly materials
Both can be recycled and reused, which is a material that saves resources and is environmentally friendly.
Pvc can achieve hygienic and non-toxic like pe
The most easily misunderstood by plastic products is the so-called "toxic and non-toxic" problem. Polyvinyl chloride is probably the deepest of these misunderstandings. Scientifically speaking, there is no toxic and non-toxic classification of plastic products, but the topic of ordinary plastics and food hygiene plastics. In fact, most plastics are non-toxic, they can be used to make food packaging, medical supplies, and even to make certain bones and organs in the human body.
Polyvinyl chloride products are available in both general and food grades. Food hygiene grade pvc products have strict requirements on the content of heavy metals in additives and vinyl chloride monomer (vcm) in pvc. However, this does not mean that ordinary grade pvc products are toxic, but not suitable for use in food hygiene. No one even thought that it could not be used or not. In general, the processing of pe material additives is small, is considered to be hygienic and non-toxic. The controversy over polyvinyl chloride is due to these two aspects. Let's do a simple analysis.
(1) Regarding the vinyl chloride (vcm) monomer problem, it does exist in the early stage of production. However, after so many years of hard work and progress, the synthesis process has become more and more perfect. Domestic chlor-alkali enterprises can produce hygienic resin with vcm content less than 5mg/kg by introducing foreign advanced technology equipment and transformation process. In addition, domestic large and medium-sized processing enterprises use advanced equipment, so the vcm content of the ultimate product will certainly not exceed 1mg/kg, which fully meets the food grade requirements.
(2) The controversy of stabilizers is mainly the topic of heavy metal content. There are different regulations for national health organizations that use different stabilizers in water supply pipelines. To date, many countries have promised to use low lead series stabilizers. They think that modern processing equipment is advanced, the amount of stable dose to be added is small, and the lead that can be dissolved from the surface of the pipe is oozing very little. The lead that can be exuded by the initial flushing during use is basically non-existent and completely safe. range. The World Health Organization (WHO) regulates the total lead content of drinking water to less than 0.01 mg/L. With the improvement of people's living standards, the pursuit of high-quality living standards, health and non-toxicity is also the direction of the development of pvc pipeline. This year, there have been stabilizer systems such as organotin, rare earth, calcium-zinc composites with better hygienic properties, making the pvc piping system completely free of lead. In 1998, the State newly promulgated the “Safety Evaluation Standard for Drinking Water Distribution Equipment and Protective Materialsâ€, which specifies that the lead content is less than 0.005 mg/L (more stringent than the WHO regulations). The production of pvc pipes with new hygienic stabilizers can fully meet the requirements of this standard.
Therefore, as long as it is through the strict requirements of the state, the pvc pipeline produced by the certified enterprise has no worries.
The use data for many years shows that the entire construction cost of upvc is 8%~10% of the main material, compared with pe pipe, the construction cost is roughly the same. Since the installation of the pe pipe is complicated, the installation site requires a construction power source to melt the joint, the technical requirements are high, and the quality requirements of the melt joint are high, and the water leakage or the joint squib is easily caused by improper operation. The pvc pipe joint is easy to install, no power supply is needed at the installation site, the installation method is simple, and it can be installed without special training, and there is little leakage or joint burst.
In summary, the plastic pipes currently used in China are still dominated by upvc pipes, which have historical reasons and scientific reasons. However, looking at the application experience and development of plastic pipes in the world, the development speed of pe pipes is obviously faster than upvc. The increasing demand for environmental protection and sanitation, as well as the country's macro-policies and market environment will stimulate the development of pe pipes and fittings. The prospects are very broad, and it is expected that the amount will gradually exceed the upvc pipe in the next few years.
Advantage of pe tube
(1) pe pipe material is non-toxic, non-corrosive, non-fouling, can effectively improve the water quality of the pipe network; pe pipe has good ability to withstand water hammer pressure, welded joint with pipe and pe pipe for underground movement and end load The effective resistance and greatly improve the safety and reliability of the water supply.
(2) pe water supply pipe special materials have been greatly developed in recent years, an important reason for the early development of pe materials is due to its uneconomical. However, after the development of high-performance polyethylene pipe special materials, the use of pe pipes has been enhanced, and the application fields of pe pipes have been expanded.
(3) The PE pipe has good flexibility and weldability, making it more convenient, economical, safer and more reliable. The pe pipe has a fast spreading speed, low damage and low maintenance cost, and can withstand the axial load without leaking and disengaging as long as the joint is good. Therefore, it is not necessary to carry out anchor points with a small degree of use at the joints and bends during the exhibition, and the support piers can be reduced in cost. The pe pipe has a unique flexibility, its elongation at break exceeds 500%, the bending radius can reach 20 to 25 times the diameter of the pipe, and it has excellent scratch resistance. Therefore, it is easy to move, bend and intersperse during the exhibition, and is suitable for various construction methods such as non-excavation pipe jacking. Moreover, the pe pipe has strong adaptability to the pipeline foundation, on the one hand, the requirements for the pipe base are reduced, and on the other hand, the pipe base changes after the exhibition, and is not easily damaged.
In a certain period of time, the pvc pipe has certain market advantages and application advantages. However, the development of the pe tube will eventually meet, even beyond the pvc tube, which is also the trend of the times. For our company, in the process of perfecting the use of pvc pipe, we must continuously improve the process level and improve work efficiency. On the other hand, we must also learn the relevant knowledge of pe pipe, cultivate relevant talents, and in the promotion and application of pe pipe, we will not be left behind, and take more obvious economic and social benefits.
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