We are always in the customer consultation and some actual projects encountered is the use of the use of PVC pipe or PE pipe, PE pipe and PVC pipe so what is the difference?
PE from R & D put to the market, to replace UPVC tube, occupy the market, become the most preferred choice for pipeline, this is a fundamental reason; first from the material characteristics of PE speaking, than to many other pipe quality; in addition, regular inspection of the market, the consumer market is from the experience the excellent quality of pe. The following analysis from several aspects, properties and application of PE pipe market compared to UPVC tube, thereby to determine the future prospects for the development of PE pipe.
I. mechanical properties of two kinds of pipes
Strength comparison of 1.1 materials at room temperature
The short-term and long-term strength of PVC material is much higher than that of PE material.
1.2 contrast between minimum requirement strength (MRS) and safety factor (C)
Both the theory and practical experience show that the MRS and safety coefficients of PVC are much higher than those of PE, that is, the strength and security of long-term use are higher than PE. Thus the same as the 75mm pipe, using PVC material than the pipe wall thickness of PE raw materials to produce more, this is due to the long-term strength and strength of PE material under normal temperature are less than PVC high, only by increasing the wall thickness to increase strength. If we take the same wall thickness, PE pipe is not up to the requirements of the use of strength. If we take the same diameter, PVC pipe diameter is PE pipe high water. If the quantity of water to achieve the same need, PE pipe larger diameter, the engineering costs increased significantly. It shows that the higher strength and rigidity of PVC material are economical for the water supply pipeline.
1.3 life comparison
Polyvinyl chloride (PVC) is a polar molecule, a vinyl chloride monomer (PE) and some small molecule is more stable, so it is not easily affected by the environment. But now, the emergence of crosslinked polymers such as vinyl chloride will improve in this regard.
2. hygiene performance comparison
2.1pvc and PE are environmentally friendly materials
Both can be recycled and reused. It is a material that saves resources and is environmentally friendly.
2.2pvc, like PE, can be hygienic and non-toxic
Plastic products most easily lead to misunderstanding is the so-called "toxic and non-toxic" problems. Polyvinyl chloride is probably one of the most misunderstood. Scientifically speaking, there is no toxic and non-toxic classification of plastic products, but the problem of ordinary plastics and food hygiene plastics. In fact, most plastics are non-toxic, which can be used for food packaging, medical supplies, and even for the production of certain bones and organs in the human body.
PVC products are of ordinary grade and food grade. Food hygiene grade PVC products have strict requirements on the content of heavy metals and vinyl chloride monomer (VCM) in pvc. This does not mean that ordinary grade PVC products are toxic, but are not suitable for use in the field of food hygiene. What's more, some people don't think they can't be used or touched. In general, the processing of PE materials, less additives, is considered hygiene non-toxic. The PVC dispute are derived from these two aspects, the following will make a simple analysis.
(1) the problem of vinyl chloride (VCM) monomer does exist in the early stage of production. However, after so many years of hard work and improve the synthetic process of maturing domestic chlor alkali enterprises through the introduction of foreign advanced technology and equipment, the transformation process and other methods can produce VCM content is lower than the sanitary resin 5mg/kg. In addition, domestic large and medium-sized processing enterprises use advanced equipment, so the final product VCM content will not exceed 1mg/kg, fully meet the food grade requirements.
(2) the dispute about stabilizers is mainly about the content of heavy metals. There are different regulations on the use of different stabilizers in the water supply pipeline. So far, many countries have allowed the use of low lead stabilizers. They think that the modern advanced processing equipment, to add a small amount of stabilizer, finally from the surface of the pipe is dissolved and the exudation of lead is very small, when used after the first washing can lead exudation basically does not exist, fully meet the safety range of use. The WHO (WHO) stipulates that the total amount of lead in drinking water is below 0.01mg/L. With the improvement of people's living standards, the pursuit of high-quality living standards, health non-toxic is also the direction of the development of PVC pipeline. This year there has been a better sanitation, organotin, rare earth, calcium zinc composite stabilizer system, so that the PVC pipe system is completely lead-free. In 1998, the state promulgated the safety evaluation standard for drinking water transmission and distribution equipment and protective materials, which stipulated that the lead content was below 0.005mg/L (stricter than the WHO regulations). The production of PVC pipes with a new hygienic grade stabilizer can meet the requirements of this standard.
So, as long as it is through the strict requirements of the country, certified enterprises to produce PVC pipes, there is no worries.
3. development overview
Since the Shanghai Municipal Construction Committee issued a decision on "galvanized steel pipe" to be used as a water supply pipe in 1998, many provinces and cities have made similar decisions. In 1999, the State Council forwarded the joint circular of the Ministry of construction and other 8 ministries and commissions on improving the quality of housing, and affirmed the decision. Since then, China's rapid development of new types of water pipes, the introduction of a variety of new types of pipe. The full development in Europe and Japan and other advanced industrial countries PVC, PE pipes, some literatures even asserted that 50mm and below the water supply pipe, PE pipe to PVC usage, accounting for 80% of the total to more than 90%. In our country, galvanized steel pipe is forbidden, and two kinds of pipes such as PVC and PE are also occupied in the domestic market
In our country, the plastic pipes used in the water supply network are mainly PVC pipes. The application of PE pipe relatively late, is relatively small. In recent ten years, with the development and application of PE pipeline in European water supply industry, PE pipeline has attracted people's attention. Especially recently, PVC has been the pressure of environmental protection, the content of PVC in Pb and CD will exceed the standard, all these make people pay more attention to pe. But this time, Beijing is at the forefront of the country in the application of PE pipe. Beijing city from the second half of 2003, water supply, gas supply network gradually using environment-friendly polyethylene (PE). Guangxi from 2003 onwards, in the new residential pipeline installation, application has been recognized as the water has no pollution with polyethylene (PE).
Present situation and development of 4.pvc and PE pipes
Since the early 80s of last century, the state has vigorously promoted the application of UPVC tubes, and has formulated a series of policies, systems and standards, and has also accumulated a lot of experience. To today, already have perfect product standards, standard testing methods and testing methods, construction engineering technical specifications, size and quality index which unifies the products, achieve product interchangeability. This shows that the development of PVC water supply pipeline has entered a mature stage, product quality and construction quality are guaranteed, so as to ensure the use of PVC water supply pipeline.
The international standard for PE pipes for water supply (ISO4427) was not officially released until 1996. In 1999, China compiled the national standard GB/T13663 with reference to ISO4427. It was promulgated 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, pipe fittings matching is not perfect, and therefore can not guarantee the quality of production and construction.
5. construction technical difficulty and cost
Years of use data show that the whole construction cost of UPVC is 8% to 10% of the main material, and the construction cost is roughly equal to that of PE pipe. The PE pipe installation is complex, the installation site requires the construction of power, can melt the joints, high technical requirements, high quality requirements and melting joint, prone to improper operation caused by Water Leakage or joint pipe explosion. The PVC pipe joint installation is convenient, the installation site does not need power supply, the installation method is simple, without special training can be installed, rarely leakage or joint burst.
To sum up, at present, the plastic pipes used in China are still mainly UPVC pipes. There are historical reasons and scientific reasons for them. But the application of experience and development in the world of plastic pipe, PE pipe development speed is significantly faster than upvc. While the requirements for the environmental and health improving day by day, and the national macro policy and market environment will stimulate the development of PE pipes and fittings, the prospects are very broad, is expected in the next few years the amount will gradually exceed upvc.