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  1. Leakage of the valve body and valve cover:
  1. The casting quality of the cast iron parts is not high, and there are defects such as blisters, loose tissue, and slag inclusions on the valve body and valve cover
  . 2. Freezing cracks in the weather;
  3. Poor welding, and there are Defects such as slag inclusions, lack of welding, and stress cracks;
  4. Cast iron valves are damaged after being hit by heavy objects.
  Maintenance methods:
  1. Ensure the casting quality, and conduct strength tests strictly in accordance with regulations before installation;
  2. Valves with temperatures between 0° and below should be insulated or heated, and valves out of use should be drained of accumulated water.
  3. The welds of the valve body and valve cover should be carried out in accordance with the relevant welding operating procedures, and flaw detection and strength tests should be carried out after welding;
  4. It is forbidden to push heavy objects on the valve, and it is not allowed to hit the cast iron with a hand hammer. And non-metallic valves, large-diameter valves should be installed with brackets.
  2. Leakage at the packing (the leakage of the valve, the proportion of the packing is ****)
  1. The packing is incorrectly selected, not resistant to the corrosion of the medium, not resistant to the use of high pressure or vacuum, high temperature or low temperature of the valve;
  2. The packing is installed incorrectly, and there are defects such as small instead of large, poor spiral coiled joints, tightening and loosening, etc.;
  3. The packing has exceeded its service life, has aged, and lost elasticity.
  4. The valve stem is not high in accuracy, and is bent, corroded, and worn. Defects such as
  5. Insufficient number of packing rings, the gland is not pressed tightly;
  6. The gland, bolts, and other parts are damaged, making it impossible to tighten the gland;
  7. Improper operation, excessive force, etc.;
  8. The gland is skewed, The gap between the gland and the valve stem is too small or too large, causing the valve stem to wear and the packing to be damaged.
  Maintenance methods:
  1. The material and type of packing should be selected according to the working conditions;
  2. The packing should be installed correctly according to relevant regulations. The packing should be placed and tightened one by one, and the joints should be at 30°C or 45°C;
  3. The service life has expired Packing that is long, aged, or damaged should be replaced in time;
  4. The valve stem should be straightened and repaired after bending or wear, and those with serious damage should be replaced in time;
  5. The packing should be installed according to the specified number of turns, and the gland should be symmetrical and even The ground handle should be tightened, and the pressure sleeve should have a pretightening gap of more than 5mm;
  6. Damaged glands, bolts and other parts should be repaired or replaced in time;
  7. The operating procedures should be followed. Except for the impact handwheel, the machine should operate at a constant speed. Force operation;
  8. The gland bolts should be tightened evenly and symmetrically. If the gap between the gland and the valve stem is too small, the gap should be appropriately increased; if the gap between the gland and the valve stem is too large, it should be replaced.
  3. Leakage of the sealing surface
  1. The sealing surface is ground unevenly and cannot form a tight line;
  2. The top center of the connection between the valve stem and the closing member is suspended, incorrect or worn;
  3. The valve stem is bent or incorrectly assembled, causing the valve to close The parts are skewed or misaligned;
  4. The quality of the sealing surface material is improperly selected or the valve is not selected according to the working conditions.
  Maintenance methods:
  1. Correctly select the material and type of the gasket according to the working conditions;
  2. Carefully adjust and operate smoothly;
  3. Bolts should be tightened evenly and symmetrically, and a torque wrench should be used if necessary. The pretightening force should meet the requirements and should not be too large or small. There should be a certain preload gap between the flange and the threaded connection;
  4. The gasket assembly should be centered and aligned, and the force should be even. Overlapping of the gaskets and the use of double gaskets are not allowed;
  5. The static sealing surface is corroded and damaged. , the processing quality is not high, repair, grinding, and coloring inspection should be carried out to make the static sealing surface meet the relevant requirements;
  6. Pay attention to cleanliness when installing the gasket, use kerosene cleaning on the sealing surface, and the gasket should not fall to the ground.
  4. Leakage at the sealing ring connection
  1. The sealing ring is not rolled tightly
  2. The sealing ring is welded to the body and the surfacing quality is poor;
  3. The sealing ring connecting threads, screws and pressure rings are loose;
  4. The sealing ring is not connected properly Corroded.
  Maintenance methods:
  1. If there is leakage at the seal rolling area, adhesive should be injected and then rolled to fix it;
  2. The sealing ring should be re-welded according to the welding specifications. When the surfacing cannot be repaired, the original surfacing and processing should be removed;
  3. Remove the screws, clean the pressing ring, replace the damaged parts, grind the sealing surface and the connecting seat, and reassemble. For parts that are severely damaged by corrosion, welding, bonding and other methods can be used to repair them;
  4. If the connecting surface of the sealing ring is corroded, it can be repaired by grinding, bonding and other methods. If it cannot be repaired, the sealing ring should be replaced.
  5. Leakage occurs when the closing parts fall off:
  1. Poor operation causes the closing parts to get stuck or exceed the top dead center, causing damage and breakage at the joints;
  2. The closing parts are not firmly connected, loose and fall off;
  3. Selection of The connecting parts are made of the wrong material and cannot withstand the corrosion of media and mechanical wear.
  Maintenance method:
  1. Correct operation. Do not use too much force to close the valve. Do not open the valve beyond the top dead center. After the valve is fully opened, the handwheel should be reversed slightly;
  2. The connection between the closing piece and the valve stem should be firm, and the threaded connection should be Stop piece;
  3. The fasteners used to connect the closing piece and the valve stem should withstand the corrosion of the medium and have certain mechanical strength and wear resistance.


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The company has rich production experience and has always adhered to the management model of a modern enterprise. Relying on its high-tech advantages, it has the ability to independently develop, design and produce. Its products are widely used in electric power, hydraulic power, heating, chemical industry, kerosene, metallurgy, fertilizer, brewing, papermaking, medicine and other fields. Due to its reliable quality, reasonable price, superior performance and sound after-sales service, it is highly praised and trusted by customers at home and abroad.

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The valves are not maintained in a timely manner, resulting in disrepair, leakage or malfunctioning switches; the valves are not regularly inspected and tested for pressure, or even used for many years without cleaning, pressure testing and technical appraisal, resulting in debris deposited in the valve, lax closure, and serious leakage. Oil, oil leakage; the valve is not closed after maintenance, or the pipe opening is not blocked after the valve is removed.

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In fluid pipeline systems, valves are control components whose main functions are to isolate equipment and pipeline systems, regulate flow, prevent backflow, regulate and relieve pressure. Since it is very important to select the most suitable valve for the pipeline system, it is also important to understand the characteristics of the valve and the steps and basis for selecting the valve.

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For a single core, when the medium is flow-open, the valve has good stability; when the medium is flow-closed, the valve has poor stability. The double-seat valve has two valve cores. The lower valve core is closed and the upper valve core is open. In this way, when working at a small opening, the closed-flow valve core will easily cause vibration of the valve. This is a double-seat valve. The reason why it cannot be used for small opening work.

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