Valves are an important part of large-scale complete sets of equipment, mainly used for cutting, throttling, regulating pressure and changing flow direction of process pipeline media (material, water, steam, air and oil). The quality of the valve directly affects the normal production, safe operation and environmental pollution of these devices and plays a vital role. There are many kinds of valve specifications, such as gate valve, globe valve, check valve, ball valve, safety valve, pressure reducing valve, steam trap, butterfly valve and special purpose valve, etc., which have wide application and large dosage. According to incomplete statistics and rough estimates, the investment in valves in a large-scale complete plant accounts for about 3% to 5% of the total investment in equipment.
(l) Valve manufacturers and production conditions There are about 180 valve enterprises managed at the county level or above, including 19 key enterprises, and there are more than 2,000 townships and individual enterprises of a certain scale. It is difficult for small individual manufacturers to count, township enterprises and individuals. The manufacturers are mostly distributed in Jiangsu, Zhejiang and Central Plains. In the valve industry, state-owned large and medium-sized enterprises, especially backbone enterprises, still have great advantages in valve manufacturing and technical strength. Some of these manufacturers use resin sand line modeling. The main components of the valve are processed on CNC machine tools, automatic lines or combination machine tools. The sealing surface is divided into spray welding technology, the valve design uses CAD technology, and three-dimensional solid modeling. Advanced technology has promoted the improvement of valve production level and product quality, and the development of science and technology is unstoppable. However, most of the valve manufacturers cast smelting equipment outdated, mainly by hand styling, machining is mostly general machine tools and single-knife cutting, testing equipment is not perfect or does not meet the standard. In recent years, some small and medium-sized valve manufacturers have strengthened management personnel, laid the foundation, equipment and technology, and gradually improved the production technology level, product quality, product quality, market grasp, considerable economic benefits, and competition with large or key enterprises. The strength and development prospects cannot be underestimated.
(2) Product level Through the implementation of national standards, technology introduction, strengthening testing and testing methods, old product transformation and improving design and process level, China's valve product level has been greatly improved in the past 20 years, and the variety specifications have increased greatly, especially in Hard-sealed butterfly valves, hard-sealed ball valves, and slab gate valves have increased in types and products (14 categories of valves currently have nearly 2,000 series, more than 12,000 specifications). The ordinary valves with a large quantity and a large area have basically reached the level of foreign countries in the 1980s. These valves are similar in terms of product structure and materials to valves produced in foreign countries in recent years, and can be produced according to foreign standards, but only in product quality. It is not stable enough and has a certain gap with developed countries. However, in some special valves (such as automatic control valve, hard seal ball valve, minimum flow valve, ash removal slag valve, main steam isolation valve and stabilizer safety valve, etc.), high-parameter valve (such as the use temperature is higher than 700 ° C, caliber More than lm ball valve), valve material (anti-hydrogen sulfide material, urea steel and carbon fiber composite material) and valve transmission and other aspects of the gap with foreign countries, the shortage of varieties, should be through the introduction of technology (including the valve to the introduction of the device Use design) and technical research to solve it step by step. The matching capacity of domestic valves can basically meet 300,000 t/a ethylene, 300,000 t/a synthetic ammonia, 520,000 t/a urea, 60,000 t/a high pressure polyethylene, 80,000 t/a polypropylene, 60,000 tons. /a ethylene glycol, 80,000 t/a vinyl chloride, 50,000 t/a acrylonitrile, 30,000 t/a acetaldehyde, 45,000 t/a butadiene, 2.5 million t/a refinery, 30,000 m3 /h air separation, 30MW thermal power station, 30MW nuclear power plant and long-distance pipeline and other devices. The scale of large-scale foreign complete sets of equipment has been continuously expanded, and the matching level of valves has been promoted. Domestically, there is such a development trend, but the supporting capacity has a large gap compared with developed countries, mainly reflected in special valves and high Parameter valves, control systems and drive units.
1, strong, thermostable
Because CPVC compares PP-R, PE-X to be firm. Compared with PP, the PE-X tube, under the similar pressure, CPVC may use a smaller caliber to achieve the same water flow, thereby saving material costs and installation time. Compares with other thermoplastic, CPVC has the remarkable mechanical property under the different temperature, is suitable for the bearing the situation, the application temperature may reach as high as 93°C, the life may amount to 50 years.
2, easy installation
The connection method are very similar with PVC. Most commonly used and simple connection method is resolver cementation. Other connection methods are threaded connection, flange connection and electrode connections.
3, non-corrosive oxygen permeability
CPVC have the anti-oxygen, therefore the oxygen seepage from the radiator will not bring metal corrosion.
4, reducing the infiltration of additives
In order to prevent oxidation, some modified plastics needs to increase the massive antioxidant that may be infiltrated into the water supply system ,causing the ill-smelling smell.
5, without the impact of chlorine in water
A lot of polyolefin materials (including PP, PE) may be decomposed with water, while CPVC is not affected by the impact of residual chlorine in water that there is no cracks and leakage.
6, good flame retardancy
CPVC limiting oxygen index is 60, therefore it will not burn in the air. It has the characteristics : misfires the flame decoction,not to increase the fire set,restrict flame spread,low smoke generation. 7, CPVC has excellent chemical resistance to non-polar strong acid and alkali. Commonly used to substitute the metal to process the corrosive material, such as the poor quality of water, acidic material alkaline matter and other peroxide solutions.
8, the low thermal conductivity
CPVC thermal conductivity is only 1.05. heat is not easy to disseminate from the pipeline, heat loss of pipeline is low.
9, bacteria breeding is not easy
CPVC is not influenced by the impact of residual chlorine in water. So it will not result in cracks and leaks. Inner wall of pipe is smooth, not easy to breed bacteria. The research indicated that the breeding of germs in CPVC pipe is far lower than other materials such as copper, steel and other plastic pipe.
10, low thermal expansion
CPVC thermal-expansion coefficient is lower than other plastics. The tube expansion is very small when tube-pass heat, unlike other types of channels (such as PP-RRP) due to the higher temperature caused by heat expansion coefficient that could cause snake bending,the existence safe hidden danger and eyesores.
11, the test of time
none of a thermoplastic material such as CPVC,avoid the maintenance after 40 year hot water system's test, and displays its excellent performance
CPVC
CPVC Fittings,CPVC Pipes,Chlorinated Polyvinyl Chloride,CPVC Tubing
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