Valve pressure test leakage test and operation method valve region share ranking

Valve pressure test leakage test and operation method valve region share ranking

When the pipeline is first used, there are more internal dirt, the valve can be slightly opened, the high-speed flow of the medium can be used to wash it away, and then gently closed (not fast closed, fierce closed, to prevent residual impurities from clamping the sealing surface), open again, so repeated many times, wash the dirt, and then put into normal work. Normally open the valve, there may be dirt on the sealing surface. When closing, the above method should also be used to wash it clean, and then formally close. If the handwheel and handle are damaged or lost, they should be completed immediately, and can not be replaced by movable plate hands, so as not to damage the stem quartet, opening and closing is not effective, resulting in accidents in production.
Operation method of valve
For valves, not only must be able to install and maintain, but also to operate.
(a) manual valve opening and closing
Manual valve is the most widely used valve, its hand wheel or handle, is designed in accordance with ordinary manpower, taking into account the sealing surface strength and the necessary closing force. So you can’t use a long lever or a long spinner. Some people are used to using the wrench, should pay strict attention to, not too much force, otherwise easy to damage the sealing surface, or plate broken hand wheel, handle.
Open and close the valve, the force should be smooth, not impact. Some impact opening and closing of high pressure valve components have taken into account the impact force and the general valve can not wait. For the steam valve, before opening, it should be heated in advance and the condensed water should be excluded. When opening, it should be as slow as possible to avoid the phenomenon of water strike.
When the valve is fully open, the handwheel should be reversed a little, so that the thread between tight, so as not to loose damage. For pole-stem valves, remember the position of the stem when fully open and fully closed, to avoid hitting the top dead point when fully open. And it is convenient to check whether it is normal when fully closed. If the valve does fall off, or between the spool seal embedded large debris, the position of the stem will change when fully closed.
When the pipeline is first used, there are more internal dirt, the valve can be slightly opened, the high-speed flow of the medium can be used to wash it away, and then gently closed (not fast closed, fierce closed, to prevent residual impurities from clamping the sealing surface), open again, so repeated many times, wash the dirt, and then put into normal work. Normally open the valve, there may be dirt on the sealing surface. When closing, the above method should also be used to wash it clean, and then formally close. If the handwheel and handle are damaged or lost, they should be completed immediately, and can not be replaced by movable plate hands, so as not to damage the stem quartet, opening and closing is not effective, resulting in accidents in production.
Some medium, cooling after the valve is closed, so that the valve parts shrink, the operator should be closed again at the appropriate time, so that the sealing surface does not leave a fine seam, otherwise, the medium from the fine seam high-speed flow, it is easy to wash the sealing surface. During operation, if it is found that the operation is too laborious, the cause should be analyzed. If the packing is too tight, it can be properly relaxed, such as the valve stem skew, should inform the personnel to repair. Some valves, in the closed state, the closed parts are heated expansion, resulting in opening difficulties; If it must be opened at this time, the cover can be unscrewed half a circle to a circle to eliminate stem stress, and then the plate to start the wheel.
(2) Matters needing attention
1, 200℃ above the high temperature valve, due to the installation at room temperature, and after normal use, temperature rise, bolt heat expansion, gap increase, so must tighten again, called “hot tight”, operators should pay attention to this work, otherwise prone to leakage.
2. When the weather is cold, the water valve should be closed for a long time, and the water should be removed after the valve. Steam valve after steam, also want to exclude condensate. The bottom of the valve is silky and can be opened to drain.
3, non-metallic valves, some hard and brittle, some low strength, operation, open and close force can not be too large, especially can not make strong force. Also take care not to knock things.
4, when the new valve is used, the packing should not be pressed too tightly, so as not to leak, so as not to pressure the stem too much, accelerate wear, and hard to open and close.
Valve pressure test leakage test
Pressure test refers to body strength test. Leakage test, refers to the sealing surface tightness test, these two tests are to check the main valve performance. The test medium is generally normal temperature water, and kerosene can be used for important valves. Safety valve constant pressure test, can use nitrogen more stable gas, also can use steam or air instead. For diaphragm valves, test with air.
(1) test pressure
Valve strength test pressure, and the nominal pressure has the following relationship
Nominal pressure (Mpa) strength test pressure (Mpa0.10.20.250.40.40.60.60.911.51.62.42.53.8466.49.610151624203025383248 by visible, nominal pressure from 0.4 Mpa – 32 Mpa, These commonly used pressure valves, their strength test pressure is 1.5 times. Valve seal test pressure, equal to the nominal pressure.
(2) Test methods
Pressure test and leakage test are carried out on the test bench. The structure of the test bench (as shown in Figure 5-1) is that there is a pressing part above the test bench and a pipeline connected with the pressure test pump below. After the valve is pressed, the pressure test pump works. From the pressure gauge of the pressure test pump, the valve can be read out the number of pressure. When the pressure test valve fills with water, the air in the valve should be drained. The pressure plate on the upper part of the test bench has an exhaust hole and is opened and closed with a small valve. A sign that the air is cleared is that all water comes out of the vent. After closing the vent, start boosting the pressure. The boost process should be slow, not sharp. After reaching the specified pressure, keep for 3 minutes, pressure does not become qualified.
Pressure test leak test procedure can be divided into three steps:
1, open the valve path, fill the valve cavity with water (or kerosene), and boost the pressure to the strength test requirements, check the valve body, valve cover, gasket, packing for leakage.
2, close the valve road, pressure on one side of the valve to the nominal pressure, check whether there is leakage from the other side.
3. Turn the valve upside down and test the opposite side.
Valve regional share ranking valve production base more than what?
Many friends have been confused than do not know what manufacturers to find valves, what brand, where the quality is better, some people said Shanghai, some people said Zhejiang, some people said Jiangsu, xiaobian in this car polite.
Valves are various and there are statistical popular type of valve is more than eight thousand, and one 5 is no statistics, have a plenty of specially designed for an enterprise, have a plenty of tailored for a particular project, not * * * used by the market, but a small portion is eliminated, always say a lot, is a mess, directly to the point that we, The following content is just a corner of the horizon, statistics of the cow hair, detailed or field visit, use good (more detailed classification of brands and regional brands please pay attention to the following article). Below we will analyze the main manufacturers around the valve classification and in the market share of the description, the data is based on the statistics of the National Bureau of Statistics (manufacturers with production licenses, the number of sales and annual tax statistics results).
Valve market share ranking:
Zhejiang: 53%
1. Oubei Town, Yongjia County, Wenzhou: 23% (ordinary valves, cast steel valves, American standard valves, etc.)
2, Wenzhou Longwan District: 15% (low-end valves, stainless steel valves, etc.)
Yuhuan County: 6% (copper valves, etc.)
Ningbo: 2.5% (plastic valves, copper valves, etc.)
Lishui: 2% (cast steel valves, American standard valves, etc.)
Hangzhou: 1.5% (regulating valve, etc.)
Yueqing: 0.5% (Marine valves, etc.)
Zhuji City: 0.5% (copper valves, fire accessories, etc.)
Yuyao: 0.5% (solenoid valve)
Remaining 1% (Ruian, Tongxiang, Taizhou)
Yancheng City, Jiangsu Province: 12.5% (joint venture valve, instrument valve, hydraulic valve, high pressure valve, etc.)
Shanghai: 7% (imported valves, ** valves, power station valves, automatic control valves, etc.)
Tianjin: 5% (low pressure valve, soft seal butterfly valve, etc.)
Guangdong Province: 4% (joint venture valves, etc.)
Fujian Province: 2.5% (ductile iron valves, fire valves, water valves, etc.)
Henan City: 2% (low pressure valves, cast iron, ductile iron valves, etc.)
Beijing: 2% (high pressure valves, etc.)
Zigong, Sichuan province: 1% (high pressure valves, power station valves, etc.)
Shandong Province: 1% (groove valves, fire valves, etc.)
Hebei Province: 1% (cast iron, ductile iron valves, etc.)
Chongqing municipality: 0.5% (solenoid valve, etc.)
The rest: 9%
The above statistics are divided according to the number of enterprises, sales, and product quantity. If there is any deviation, please refer to the actual situation.