PVC is polymerized from vinyl chloride monomer (VCM). PVC material is non-toxic, anti-aging, acid and alkali resistant, so it is very suitable for use in chemical pipelines. A mixture composed of PVC raw materials and a certain amount of solid additives (without plasticizers) is called rigid polyvinyl chloride (UPVC). Due to its excellent economic performance and characteristics, UPVC pipes are widely used nationwide, and their superiority is gradually replacing traditional steel pipes. The advantages of using UPVC pipes in water treatment projects:
1. Stable physical and chemical properties: UPVC pipes cannot burn or support combustion, and have good water pressure resistance, impact resistance, and tensile strength. Chemical stability, corrosion resistance, wear resistance, acid alkali salt oil medium corrosion resistance. It is non-conductive and not corroded by electrolysis or current. The unique mechanical properties of UPVC material enable it to be used normally for 50 years, with reduced maintenance frequency and lower operating costs;
2. Good hydraulic performance: According to hydraulic calculations, the maximum water carrying capacity of UPVC pipes is 50% higher than that of traditional carbon steel pipes, with low resistance, high flow rate, smooth inner wall, and low fluid flow loss. It is not easy for dirt to adhere to the smooth pipe wall;
3. Convenient construction: UPVC pipes are lightweight, with a specific gravity only 1/10 of cast iron, and easy to transport. Its connection form is socket bonding, which can be connected using specific adhesive. Practice has proven to be reliable, safe, easy to operate, cost-effective, and easy to install, saving expenses and shortening the construction period;
4. Appearance: The outer wall of UPVC pipe is smooth, does not require anti-corrosion treatment, is easy to clean, has simple maintenance, and has extremely low maintenance costs. It has good visual effects and can improve the working environment of the water treatment workshop. Given the above advantages, UPVC pipes are widely used in water treatment design. Based on my practical experience in water treatment engineering, the author proposes the following points for reference by peers:
1. The quality of pipes and fittings is the material guarantee of pipeline engineering, and the procurement principle is "quality first, price follows quality". At present, there are over 400 manufacturers of various sizes producing and selling UPVC in the market, and the quality varies greatly. Some manufacturers engage in disgusting competition by arbitrarily lowering prices (focusing on raw materials and formulas). However, it is often difficult to accurately inspect the quality of UPVC pipes based on their appearance. Therefore, many users purchase inferior products only considering the price, resulting in engineering accidents and losses that greatly exceed the value of the material itself;
2. As mentioned earlier, the installation process of UPVC pipes and fittings is simple, and adhesive bonding is used. It is precisely because of this that some on-site installation workers may encounter problems such as uneven glue application and inadequate interface insertion in order to pursue project progress, resulting in leakage and dripping in a short period of time after water supply. The main reason is that on-site workers lack basic knowledge and strong sense of responsibility;
3. As a plastic product, UPVC pipes have poor rigidity and a large expansion coefficient. Therefore, it is necessary to choose supports reasonably. During construction, attention must be paid to the maximum spacing between supports and strict adherence to design and construction specifications.
