The commonly used medium for valve pressure test is water, oil, air, steam, nitrogen, etc., and the pressure test methods of various valves are as follows.
(1) Globe valve and throttle valve For the strength test of globe valve and throttle valve, the assembled valve is usually placed in the pressure test frame, the valve disc is opened, the medium is injected to the regular value, and the valve body and valve cover are checked for sweat and leakage. Strength tests can also be performed on a single piece. The tightness test is only done for the shut-off valve. During the experiment, the stem of the globe valve is straight, the disc is open, and the medium is introduced from the bottom end of the disc to the regular value, and the packing and gasket are checked; After passing the test, close the disc and open the other end to see if there is any leakage. If the valve strength and tightness test are to be done, the strength test can be done first, and then the pressure can be lowered to the value of the tightness test rule, and the packing and gasket can be checked; Then close the disc and open the outlet to see if the sealing surface is leaking.
(2) Gate valves
The strength test of a gate valve is the same as that of a shut-off valve.
There are two methods for the tightness test of the gate valve.
(1) The ram is open to raise the pressure in the valve to the regular value; Then close the gate, take out the gate valve immediately, check whether there is leakage at the seals on both sides of the gate or directly inject the experimental medium into the plug on the valve cover to the regular value, and check the seals on both sides of the gate. The above method is called intermediate pressure test. This method is not suitable for sealing experiments on gate valves with nominal diameter below DN32mm.
(2) Another method is to open the ram to raise the test pressure of the valve to the regular value; Then close the gate, open the blind plate at one end, and check whether the sealing surface is leaking. Then turn your head and repeat the above experiment until you are qualified.
The tightness test at the gate valve packing and gasket should be performed before the gate tightness test.
(3) Ball valves
The strength test of the ball valve should be carried out under the condition that the ball is half open.
(1) Floating ball valve tightness test: the valve is in a half-open state, one end is introduced into the experimental medium, and the other end is closed; Roll the ball several times, open the closed end when the valve is in a closed state, and check the sealing function at the packing and gasket together, and there shall be no leakage. Then the experimental medium is introduced from the other end,www.sypv.comRepeat the above experiment.
(2) Tightness test of fixed ball valve: before the experiment, the ball is rolled several times without load, and the valve is in a closed state, and the experimental medium is drawn to the regular value from one end; Use the pressure gauge to check the sealing function of the introduction end, and use the pressure gauge with an accuracy of 0.5-1 grade, and the range is 1.6 times of the experimental pressure. In the rules of the question, there is no blood pressure reduction phenomenon is qualified; Introduce the experimental medium from the other end and repeat the above experiment.
Then, the valve is in a half-open state, both ends are closed, the inner cavity is filled with medium, and the packing and gasket are checked under the experimental pressure without leakage.
(3) Three-way ball valves should be tested for tightness in all directions.
(4) Plug valve
(1) When the plug valve is tested for strength, the medium is introduced from one end, the rest of the channels are closed, and the plug is rotated to the full open operation direction for the experiment, and the valve body is qualified if no leakage is found.
(2) During the tightness test, the straight-through should insist that the pressure in the cavity is equal to the passage pressure, rotate the plug to the closed position, check it from the other end, and then rotate the plug 180° to repeat the above experiment; Three-way or four-way plug valves should insist that the pressure in the cavity is level with one end of the channel, rotate the plug to the closed position in turn, and the pressure is introduced from the right-angle end and viewed from the other ends.
Before the plug test, a layer of non-acidic dilute lubricating oil is allowed to be applied to the sealing surface, and no leakage and expansion of water droplets are found within the regular time to be qualified. The test time of the plug valve can be shorter, generally according to the nominal diameter rule of l-3min.
The plug valve used for coal gas should be tested for air tightness at 1.25 times the operating pressure.
|
More on that
|
Reasons and solutions for the loose closure of the valve - Wuzhong instrument
Valves often present some troublesome problems in the process of use, such as the valve is not closed tightly, not tight, so what should I do?
Under normal circumstances, if it is not tightly closed, first admit whether the valve is closed in place, if it has been closed in place, it still exists.
|
|
The role of the filter - Wu Zhong meter
The filter is an indispensable product in the fluid pipeline, which is generally installed at the inlet end of the pressure relief valve, pressure reducing valve and water level valve set equipment, which has the effect of eliminating impurities in the medium and avoiding the phenomenon of other equipment being stuck. After the medium passes through the filter cartridge equipped with a certain standard screen, the impurities are blocked.
|
|
Types of solenoid valves and their respective principles and characteristics
Solenoid valve is an industrial equipment controlled by solenoids, and is a basic element of automation used to control fluids, which belongs to actuators and is not limited to hydraulics and pneumatics. It is used in industrial control systems to adjust the direction, flow rate, speed and other parameters of the medium. Solenoid valves can be used with different circuits to ...
|
|
The relationship between the valve diameter and the flow rate of the medium
The flow rate and velocity of the valve mainly depend on the diameter of the valve, and are also related to the resistance of the structure of the valve to the medium, and at the same time have an intrinsic relationship with the pressure, temperature and concentration of the medium of the valve.
Two...
|
|
China's control valve industry leading enterprises - Wuzhong instrument
Wuzhong is a leading enterprise in China's process industry automatic control valve industry, founded in 1959, a national third-line construction enterprise. The company has always adhered to the concept of professionalism, dedication, innovation and transcendence.
|
|
Check valve selection points - Wuzhong instrument
Check valve, also known as check valve, check valve, is a valve used to avoid the backflow of medium in the pipeline, belongs to a class of active valves, because the pump in the abort operation, the medium will flow backwards, if there is no device check valve at this moment, the water hammer effect will occur in the process of backflow, the pipeline ...
|
|
Problems and solutions of pneumatic butterfly valves - Wuzhong instrument
1. The signal valve pushed by the control box does not move. Under the condition that the positioner is installed, the pneumatically adjustable butterfly valve is equipped with a solenoid valve. The weak current of the solenoid valve affects the information output of the control box, and the valve cannot withstand the data signal and cannot work normally.
...
|
|
Matters to be paid attention to in the selection of conventional valves - Wuzhong instrument
Valve application requirements
(1) General gate valves, ball valves, and globe valves are prohibited from regulating according to their structural characteristics. However, in process design, it is widely used for mediation. Due to the conditioning application, the valve seal is in a throttling state for a long time, and the impurities in the oil wash the seal, damaging the seal.
|
|
Pneumatic control valve inspection parts and daily maintenance - Wuzhong instrument
Pneumatic control valve is one of the instruments widely used in petrochemical enterprises. It is of great significance to ensure the normal operation and safe production of the process equipment by operating accurately and normally. Therefore, it is necessary to strengthen the maintenance of pneumatic control valves.
First, the key points to check the location during maintenance
...
|
|
Wuzhong instrument control valve components
1. Valve body assembly
The valve body assembly shall have the following elements: structural type, nominal diameter, nominal pressure, connection type with pipeline, applicable temperature scale, raw materials of valve body and internals, valve seat diameter or rated flow coefficient, flow characteristics, valve seat leakage grade, etc.
...
|
|
Structural requirements for thermocouples in Wuzhong instruments
The structure of the thermocouple is to ensure the stable operation of the thermocouple, and the requirements are as follows:
The two thermoelectrodes that make up the thermocouple must be strong on the weld to maintain good quality.
|
|
Wuzhong instrument spherical core processing island
A few days ago, in a large digital workshop of Wuzhong Instrument Co., Ltd., the operators were working carefully. Every day, tens of thousands of parts orders are sent from dozens of sales outlets across the country such as Guangzhou and Hainan, and nearly 200 pieces of equipment in the workshop are processed and produced.
Because of the working conditions ...
|
|
Precautions for valve installation - Wuzhong instrument
1. Before the device, check whether the valve has notched parts, whether the type is correct, whether there are debris in the valve body, and whether the muffler is blocked.
2. Close the valve and cylinder.
3. Device the cylinder on the valve, the direction of the equipment is parallel or straightened with the valve body, and check whether the screw holes are aligned.
|
|
What valve manufacturing technologies does Wuzhong Instrument have?
1) Casting: a kind of data molding method. The molten metal liquid is placed into the mold of the desired shape, allowed to condense, cooled and then removed from the product.
2) Forging: After heating the metal profile ...
|
|
Features of pneumatic regulating stainless steel butterfly valve - Wuzhong instrument
Product features of pneumatic conditioning stainless steel butterfly valves:
1. Simple, small size, light weight, small flow resistance, large flow coefficient and good sealing performance. Large conditioning range. It is the fulfillment unit of the instrument in the automatic control system.
2、 ...
|
|
The torque of the electric actuator of the valve is faulty
1. Torque maintenance refusal
To measure the output torque of the electric actuator, there are mainly mechanical maintenance switches, motor current and voltage power measurement and calculation torque, and sensor-type maintenance devices: mechanical torque maintenance switches were used more before 2000 and were classified as a transitional product.
|
|
Wuzhong instrument gate valve movement mode
When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, only rely on the medium pressure to press the sealing surface of the ram to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves are forcibly sealed, that is, when the valve is closed, it is necessary to rely on external force to forcibly ...
|
|
How to use thermocouples in Wuzhong meters
The correct use of thermocouples can not only accurately obtain the temperature value and ensure that the product is qualified, but also save the data consumption of thermocouples, which can not only save money but also ensure product quality. Incorrect installations, errors such as thermal conductivity and time lag are the first errors in the use of thermocouples.
|
|
Technical requirements for valve assembly - Wuzhong instrument
Valve is a kind of commonly used hardware products, the valve in the assembly and installation process also has a certain skill requirements, otherwise the assembled valve may not show its own excellent performance, what are the skill requirements of the valve in the assembly process?
...
|
|
The working principle and application place of the shut-off valve - Wuzhong instrument
The shut-off valve is a kind of actuator in the automation system, which is composed of a multi-tension spring pneumatic membrane actuator or a floating piston actuator and a regulating valve, which receives the signal of the regulating instrument and controls the blocking, switching or switching of the fluid in the process pipeline. It has a simple structure, sensitive response, and ...
|
|
Contact
working hours
