Ball Valve maintenance skills

With the development of social economy, Ball Valve are used more and more widely. There are many types of Ball Valve used in pipelines, with different structures. They are also the most easily damaged pipeline accessories. The maintenance of each Ball Valve should be carried out according to the specific structure. There are many types of Ball Valve used in pipelines, with different structures. They are also the most easily damaged pipeline accessories. The maintenance of each Ball Valve should be carried out according to the specific structure. 1. Inspection and repair of valve body and valve cover The valve body and valve cover are the outermost closed shell of the Ball Valve, which are used to withstand the pressure of the medium, the additional force during operation, the weight of other parts of the Ball Valve, and the tightening force of the flange or thread at the connection. The valve body and valve cover are required to have a certain strength and rigidity. Their damage is mainly caused by local defects caused by medium corrosion, erosion and mechanical damage. When the wall is thinned due to corrosion or erosion, which affects their strength and rigidity, it cannot be repaired and should be replaced. During inspection and repair, the valve body and valve cover should first be tested for water pressure strength, and then their tightness should be checked with water, compressed air, kerosene or other media. The defects of the valve body and valve cover are generally repaired by welding, and the corresponding welding rods and welding processes are selected according to the different materials. The defective metal should be cleaned before welding, and it should be inspected and trimmed after welding, and stress should be eliminated. 2. Inspection and repair of packing chamber The inspection and repair of the packing chamber includes the replacement of packing and the inspection and repair of the packing box. When selecting packing, the use conditions and the medium must be considered. Generally speaking, oil-impregnated asbestos packing is suitable for air, steam, water and heavy oil products at a certain temperature. Graphite asbestos packing can be used under high temperature and high pressure conditions, especially graphite asbestos packing with steel wire has better pressure resistance. Asbestos plus lead packing can be used for high temperature and frequently changing temperature media. For highly corrosive media, polytetrafluoroethylene asbestos packing or polytetrafluoroethylene braiding can be used.

06 November-2024

Brief description of common faults of Ball Valve

Ball Valve are frequently used in industrial production. This type of Ball Valve has the advantages of high cost performance, wide range of action, and good safety assurance. In the process of large-scale and long-term use, Ball Valve will inevitably have some large and small faults. Let's take a look at how these faults should be handled? The faults that often occur on this type of Ball Valve can often be divided into two categories. The first common fault is Ball Valve leakage. Once there is a leakage problem, you need to stop the operation of the entire machine immediately, and effectively find out the cause of the leakage of the Ball Valve and solve it accordingly. Generally speaking, the problem of leakage usually occurs because some parts in the Ball Valve have poor contact with the base, there is a gap in the middle, or some impurities in the production process run into the Ball Valve, causing obstructions and gaps, so as long as the cause of the problem is found, it can generally be easily solved by the staff. Another type of problem is that the Ball Valve does not work, that is, when the valve set pressure value is reached, the Ball Valve does not open automatically. There are usually more cases like this. For example, some may be that the Ball Valve has been used for too long, and the valve core and the valve seat may be stuck together due to oil pollution and other problems, so it cannot work. It may also be a problem with the settings above. The spring pressure value inside the Ball Valve is adjusted too large, which makes its sensing valve value relatively high, so it cannot sense normally. For this kind of problem, it is best to ask professional maintenance personnel to detect and find it, and carry out targeted repairs to restore it to normal.

05 November-2024

The installation and maintenance of the Ball Valve should pay attention to the construction and installation points of the following matters

1. Installation position, height, import and export direction must meet the design requirements. Note that the direction of the medium flow should be consistent with the direction of the arrow of the valve body, and the connection should be firm and close. 2. Before installation of the valve, the appearance inspection must be performed. The nameplate of the valve shall comply with the provisions of the current national standard "General Valve Sign" GB 12220. For a valve that is greater than 1.0 MPA and a cutting effect on the main pipe, the intensity and strict performance test should be performed before installation, and the rear is used for accumulation. 3. During the intensity test, the test pressure is 1.5 times the nominal pressure, and the duration is not less than 5min. The valve shell and the fillers should be qualified without leakage. During the tight test, the test pressure is 1.1 times the nominal pressure; the duration of the test meets the requirements of GB 50243. 4. Various Ball Valve should be installed vertically. 5. There should be no resistance at the exit of the Ball Valve to avoid compression. 6. Before installation, the Ball Valve should be tested and checked its official sealing. 7. Regular inspections should be checked on the Ball Valve in use.

04 November-2024

Selection principles of Ball Valve

1. For steam boiler Ball Valve, open full-lift spring Ball Valve 0490 series are generally used; 2. For Ball Valve for liquid media, micro-lift spring Ball Valve 0485 series are generally used; 3. For Ball Valve for air or other gaseous media, closed full-lift spring Ball Valve are generally used; 4. For Ball Valve for liquefied petroleum gas tank cars or liquefied petroleum gas railway tank cars, full-lift built-in Ball Valve are generally used; 5. For Ball Valve for oil well outlets, pilot Ball Valve are generally used; 6. For high-pressure bypass Ball Valve for steam power generation equipment, pilot Ball Valve with dual functions of safety and control are generally used 7. If the Universal Valve is required to be opened regularly, a Universal Valve with a lifting wrench should be used. When the medium pressure reaches more than 75% of the opening pressure, the valve disc can be slightly lifted from the valve seat with a lifting wrench to check the flexibility of the Universal Valve opening; 8. If the medium temperature is high, in order to reduce the temperature of the spring chamber, generally when the closed Universal Valve temperature exceeds 300℃ and the open Universal Valve temperature exceeds 350℃, a Universal Valve with a radiator should be selected; 9. If the back pressure at the Universal Valve outlet is variable and the change exceeds 10% of the opening pressure, a bellows Universal Valve should be selected; 10. If the medium is corrosive, a bellows Universal Valve should be selected to prevent important parts from failing due to corrosion by the medium.

01 November-2024

Common faults and elimination methods of Ball Valve

(1) The valve disc does not return to the seat after discharge This is mainly caused by the spring bending the valve stem, the valve disc is not installed correctly or is stuck. It should be reassembled. (2) Leakage Under the normal working pressure of the equipment, leakage between the valve disc and the valve seat sealing surface exceeds the allowable level. The reasons are: there is dirt between the valve disc and the valve seat sealing surface. You can use a lifting wrench to open the valve several times to flush out the dirt; the sealing surface is damaged. It should be repaired by grinding or turning and then grinding according to the degree of damage; the valve stem is bent, tilted, or the lever and the fulcrum are tilted, causing the valve core and the valve disc to be misaligned. It should be reassembled or replaced; the spring elasticity is reduced or lost. Measures such as replacing the spring and re-adjusting the opening pressure should be taken. (3) It does not open when the specified pressure is reached The reason for this situation is that the set pressure is inaccurate. The compression of the spring or the position of the weight should be readjusted; the valve disc and the valve seat are stuck. The Ball Valve should be manually vented or drained regularly; the lever of the lever-type Ball Valve is stuck or the weight is moved. The position of the weight should be readjusted and the lever should move freely. (4) The pressure continues to rise after exhaust This is mainly because the selected Ball Valve has a small displacement and the safe discharge volume of the equipment. A suitable Ball Valve should be selected again; the center line of the valve stem is not straight or the spring is rusted, so the valve disc cannot be opened to the required height. The valve stem should be reassembled or the spring should be replaced; the exhaust pipe is not cut enough, and an exhaust pipe that meets the safe discharge area should be adopted. (5) The valve disc jumps or vibrates frequently This is mainly due to the excessive stiffness of the spring. A spring with appropriate stiffness should be used instead; the adjustment ring is improperly adjusted, resulting in too high return pressure. The position of the adjustment ring should be readjusted; the resistance of the discharge pipe is too large, resulting in excessive discharge back pressure. The resistance of the discharge pipe should be reduced. (6) It does not open until the specified pressure is reached This is mainly due to inaccurate set pressure; the spring is aged and the elasticity decreases. The adjustment screw should be properly tightened or the spring should be replaced.

31 October-2024