Several categories of valve products in China

There are more than 2300 valve manufacturers in the domestic market. There are several categories of valve products, more than 3500 varieties and more than 40000 specifications. Let's introduce the classification of valves! Valves for Urban Buildings: Low pressure valves are generally used in urban construction systems. At present, they are developing in the direction of environmental protection and energy saving. Environmentally friendly rubber plate valve, balance valve, midline butterfly valve and metal seal butterfly valve are gradually replacing low-pressure iron gate valve. The valves required for domestic urban buildings are mostly balance valves, soft seal gate valves, butterfly valves, etc. Valves for urban heating: In the urban heat generation system, a large number of metal hard sealing butterfly valves, horizontal balance valves and directly buried ball valves are required. Because these valves solve the problems of vertical and horizontal hydraulic imbalance of pipelines, so as to achieve the purpose of energy saving and heat generation balance. Valves for environmental protection: In the domestic environmental protection system, the water supply system mainly needs midline butterfly valve, soft seal gate valve, ball valve and exhaust valve (used to remove the air in the pipeline). The sewage treatment system mainly needs soft seal gate valve and butterfly valve. Valves for urban gas: Urban gas accounts for 22% of the whole natural gas market, with large consumption of valves and many types. It mainly needs ball valve, plug valve, pressure reducing valve and safety valve. Valves for long-distance pipeline: Long distance pipelines are mainly crude oil, finished products and natural pipelines. The valves with most demand for this kind of pipeline are forged steel three body full-diameter ball valve, sulfur resistant flat gate valve, safety valve and check valve. Valves for petrochemical plants: a. For oil refining units, most of the valves required by oil refining units are pipeline valves, mainly gate valves, globe valves, check valves, safety valves, ball valves, butterfly valves and steam traps. Among them, the demand for gate valves accounts for about 80% of the total number of valves (valves account for 3% ~ 5% of the total investment of the unit). b. Chemical fiber devices, chemical fiber products mainly include polyester, acrylic and vinylon. The required valves are ball valve and jacketed valve (jacketed ball valve, jacketed gate valve and jacketed stop valve). c. Acrylonitrile unit. The device generally needs valves produced according to API standard, mainly including gate valve, stop valve, check valve, ball valve, drain valve, needle valve and plug valve. Among them, gate valve accounts for about 75% of the total number of valves. d. Ammonia plant. Due to the different synthetic ammonia and purification methods, the process flow is different, and the technical performance of the required valves is also different. At present, domestic ammonia plants mainly need gate valve, stop valve, check valve, drain valve, butterfly valve, ball valve, diaphragm valve, regulating valve, needle valve, safety valve and high temperature and low temperature valve. Among them, the stop valve accounts for 53.4% of the total data of valves for the unit, the gate valve accounts for 25.1%, the drain valve accounts for 7.7%, the safety valve accounts for 2.4%, and the regulating valve, low temperature valve and others account for 11.4% e. Ethylene plant is the leading device of petrochemical industry, which needs a wide variety of valves. Gate valve, globe valve, check valve and lifting rod ball valve account for the majority, of which gate valve shall take the lead“ In the tenth five year plan, 6 sets of ethylene plants with an annual output of 660000 tons need to be built in China, and the demand for valves is considerable. In addition, large ethylene and high-pressure polyethylene units also need ultra-high temperature, lower temperature and ultra-high pressure valve series products. f. Air separation unit“ "Air separation" means air separation. The device mainly needs stop valve, safety valve, check valve, regulating valve, ball valve, butterfly valve and low-temperature valve. g. Polypropylene device, polypropylene is a polymer compound polymerized with propylene as raw material. The device mainly needs gate valve, stop valve, check valve, needle valve, ball valve and drain valve. Power station valves: The construction of power stations in China is developing in the direction of large-scale, so large-diameter and high-pressure safety valves, pressure reducing valves, stop valves, gate valves, butterfly valves, emergency shut-off valves, flow control valves and spherical sealing instrument stop valves are required. (according to the National Tenth Five Year Plan, in addition to Inner Mongolia and Guizhou provinces, more than 200000 kW units can be built, Other provinces and cities can only build units of m

The classification and structure of ball valves are briefly described

Ball valves include: floating ball valve, fixed ball valve, track ball valve, V-shaped ball valve, three-way ball valve, stainless steel ball valve, cast steel ball valve, forged steel ball valve, ash unloading ball valve, sulfur resistant ball valve, pneumatic ball valve, electric ball valve, ferrule ball valve and welded ball valve. According to the classification of shell / main body materials, ball valves can be divided into: 1. Metal valves: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves and copper alloy valves Doors, aluminum alloy valves, lead alloy valves, etc. 2. Metal body lined valves: such as rubber lined valves, fluorine lined valves, lead lined valves, plastic lined valves and enamel lined valves. 3. Non metallic valves: such as ceramic valves, glass valves and plastic valves. There are many domestic manufacturers of ball valves, and most of the connection sizes are not unified. It is mainly divided into the following categories: The ball of the ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure the sealing of the outlet end. Structure of ball valve: The sealing performance is good, but the load of the working medium borne by the ball is transmitted to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball medium. When impacted by high pressure, the ball may deviate. This structure is generally used for medium and low pressure ball valves. The ball of the ball valve is fixed and does not move after being pressurized. Fixed ball valves are equipped with floating valve seats. After being subjected to medium pressure, the valve seats move, so that the sealing ring is tightly pressed on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, with small operating torque. It is suitable for high-pressure and large-diameter valves. In order to reduce the operating torque of the ball valve and increase the reliability of sealing, an oil sealed ball valve appears. It not only injects special lubricating oil between the sealing surfaces to form an oil film, which not only enhances the sealing performance, but also reduces the operating torque. It is more suitable for high-pressure and large-diameter ball valves.

Precautions for ball valve maintenance

1、 Re locking at packing If there is slight leakage at the packing, the valve stem nut must be locked again. But do not lock it too tightly. Usually lock it for 1 / 4 ~ 1 turn, and the leakage will stop. 2、 Replace the valve seat and seal 1. Dismantle Keep the valve in the half open position, flush and remove the possible hazardous substances inside and outside the valve body, close the ball valve, remove the connecting bolts and nuts on the flanges on both sides, and then completely remove the valve from the pipeline. Remove the driving device - actuator, connecting bracket, lock washer, valve rod nut, butterfly spring, gnan, wear plate and valve rod packing in sequence. Remove the body cover connecting bolts and nuts, separate the valve cover from the valve body, and remove the valve cover gasket. Confirm that the ball valve is in the "off" position, which can easily take it out of the valve body, and then take out the valve seat. Gently push the valve stem down from the middle hole of the valve body until it is completely taken out, and then take out the O-ring and the packing under the valve stem. However, be careful to avoid scratching the valve stem surface and the sealing part of the valve body stuffing box. 2. Reassemble Clean and inspect the removed parts. It is strongly recommended to replace the sealing parts such as valve seat and bonnet gasket with spare parts package, assemble in the reverse order of disassembly, and cross lock the flange connecting bolts with the specified torque. Lock the valve stem nut with the specified torque. After installing the actuator, input the corresponding signal to drive the valve core to rotate by rotating the valve stem to make the valve open and close. If possible, please conduct pressure seal test and performance test on the valve according to relevant standards before reinstalling the pipeline.