1. Leakage of water pump valve body and valve cover
Cause of leakage:
1. The casting quality of the cast iron parts is not high, and the valve body and the valve cover body have defects such as sand holes, loose structure, and slag inclusion.
2. Freeze cracking.
3. Poor welding, there are defects such as slag inclusion, unwelded, stress cracks and so on.
4. The cast iron valve is damaged after being hit by a heavy object.
Maintenance method:
1. Improve the casting quality, and perform the strength test in strict accordance with the regulations before installation;
2. For valves with air temperature below 0 ° and below 0 °, heat preservation or heat mixing should be carried out, and the valves that are out of use should exclude accumulated water;
3. The welding seam of the valve body and valve cover composed of welding shall be carried out in accordance with the relevant welding operation regulations, and the flaw detection and strength test shall be carried out after welding;
4. It is forbidden to push and place heavy objects on the valve, and it is not allowed to hit the cast iron and non-metallic valve with a hammer.
The specific treatment method of valve body leakage:
1. Bonding method
Taking advantage of the fast curing speed of the adhesive, the adhesive is coated with adhesive in a timely manner to establish a new solid sealing structure to achieve the purpose of stopping leakage. It is a method of plugging with pressure by using the special function of adhesive.
For the trachoma parts with small pressure medium and small leakage, you can first polish the metal gloss near the leakage point, and then use the taper pin to align with the leakage point, and drive in with appropriate strength.
During operation, the top pressure mechanism is fixed on the side of the regulating valve. The high-speed top pressure screw makes the axial direction of the top pressure screw face the leakage point. Rotate the top pressure screw and use the rivets at the end of the top pressure screw to firmly press the leak At the site, the leak is forced to stop.
2. Welding method
A) When the pressure of the leakage medium of the valve body is low and the leakage volume is small, a nut with an inner diameter more than twice the leakage point can be used to let the leakage medium flow out from the nut and weld the nut to the valve body. Add a bolt with the same specifications as the nut, place a rubber pad or asbestos pad on the bottom of the nut, screw the top of the bolt around the raw tape and screw it into the nut to achieve the purpose of preventing leakage.
For the valve body with high leakage medium pressure and large leakage volume, drainage welding method can be used. First, use an iron plate with a round hole in the middle. Weld an isolation valve commensurate with the round hole to the round hole of the iron plate. Open the isolation valve and fit the center hole of the iron plate to the leakage point and fit it to the valve body. Let the leaking medium flow out through the center hole of the iron plate and the isolation valve.
B) The leakage medium in the valve body is of high temperature and high pressure, but the adjustment valve has a large shape and size, and the leakage is not large. Welding can also be used. First, directly weld all the gaps on the valve body related to the leakage point (not weld the leakage point), and then use a length of pipe that meets the working conditions (working temperature, pressure) according to the site environment (generally about 200mm) , Its diameter should be larger than the leak point, weld a regulating valve suitable for the pipe to one end of the pipe, and fully open the regulating valve, then weld the other end of the pipe to the leak point, and close the regulating valve to stop leakage.
If the bonding surface is not good, you can place rubber or asbestos pads on the bonding surface, then weld the iron plate near the valve body, and then close the isolation valve to achieve the purpose of resealing.
2. Leakage at the packing of the pump valve
Cause of leakage:
1. Wrong choice of filler, not resistant to medium corrosion, not tolerant to high pressure or vacuum, high temperature or low temperature of the valve;
2. The packing is not installed properly, and there are defects such as small-to-large, poor spiral coiled joints, loose tightening, etc .;
3. The filler exceeds the service period, has aged, and has lost its elasticity;
4. The precision of the valve stem is not high, and there are defects such as bending, corrosion and wear;
5. The number of packing circles is insufficient, and the gland is not compressed;
6. The gland, bolts, and other parts are damaged, so that the gland cannot be compressed;
Maintenance method:
1. The material and type of filler should be selected according to the working conditions;
2. Install the packing correctly according to the relevant regulations, the packing should be placed tightly circle by circle, and the joint should be 30 ℃ or 45 ℃;
3. Packing that is too long-lived, aging or damaged should be replaced in time;
4. After the valve stem is bent or worn, it should be straightened and repaired. If it is seriously damaged, it should be replaced in time;
5. The packing should be installed according to the specified number of turns, the gland should be tightened symmetrically and evenly, and the pressure sleeve should have a preload gap of more than 5mm;
6. The damaged gland, bolt and other parts should be repaired or replaced in time;
7. Observe the operating regulations, except for the impact handwheel, operate at a normal speed and normal force;
8. The gland bolts should be tightened evenly and symmetrically. If the gap between the gland and the stem is too small, the gap should be increased appropriately; if the gap between the gland and the stem is too large, it should be replaced.
3. Leakage of the sealing surface of the pump valve
Cause of leakage:
1. The sealing surface is unevenly ground and cannot form a close line;
2. The top of the connection between the valve stem and the closing part is suspended, not correct or worn;
3. The valve stem is bent or incorrectly assembled, causing the closing piece to be skewed or out of alignment;
4. The quality of the sealing surface material is not selected properly or the valve is not selected according to the working conditions.
Maintenance method:
1. The material and type of the gasket are selected correctly according to the working conditions;
2. The bolts should be tightened evenly and symmetrically. If necessary, a torque wrench should be used. The pre-tensioning force should meet the requirements. There should be a certain pre-tightening gap between the flange and the thread connection;
3. The gasket assembly should be aligned and aligned evenly, and the stress is uniform. The gasket is not allowed to overlap and use double gaskets;
4. The static sealing surface is corroded, damaged, and the processing quality is not high. Repair, grinding, and color inspection should be carried out to make the static sealing surface meet the relevant requirements;
5. Please pay attention to clean when installing the gasket, the sealing surface should be cleaned with kerosene, and the gasket should not fall to the ground.
4. Leakage at the joint of the pump valve sealing ring
Cause of leakage:
1. The sealing ring is not rolled tightly;
2. The sealing ring is welded to the body, and the welding quality is poor;
3. The connection thread, screw and pressure ring of the seal ring are loose;
4. The sealing ring is connected and corroded.
Maintenance method:
1. Leakage at the sealing and rolling place should be injected with adhesive and then fixed by rolling;
2. The sealing ring should be repaired in accordance with the welding specifications. The original surfacing and processing should be removed when the surfacing cannot be repaired;
3. Remove the screws and wash the pressure ring, replace the damaged parts, grind the sealing surface of the seal and the connecting seat, and reassemble. Welding, bonding and other methods can be used to repair large parts damaged by corrosion;
4. The connection surface of the sealing ring is corroded, and it can be repaired by grinding, bonding, etc., and the sealing ring should be replaced when it cannot be repaired.
5. the valve closing part of the water pump falls off and leaks
Cause of leakage:
1. Poor operation makes the closing piece stuck or exceeds the top dead center, and the connection is damaged and broken;
2. The closing piece is not firmly connected, and loose and fall off;
3. The material of the connecting piece is wrong, and it can not bear the corrosion of the medium and mechanical wear.
Maintenance method:
1. For correct operation, the valve should not be closed with too much force, and the valve should not exceed the top dead center. After the valve is fully opened, the handwheel should be reversed a little;
2. The closing piece should be firmly connected to the valve stem, and there should be a retreat piece at the thread connection;
3. The fastener used to connect the closing piece to the valve stem should withstand the corrosion of the medium and have a certain mechanical strength and wear resistance.
4. Improper operation, excessive force, etc .;
5. The gland is skewed, and the gap between the gland and the stem is too small or too large, causing the stem to wear and the packing to be damaged.
Pump valve maintenance method:
1. The material and type of filler should be selected according to the working conditions;
2. Install the packing correctly according to the relevant regulations, the packing should be placed tightly circle by circle, and the joint should be 30 ℃ or 45 ℃;
3. Packing that is too long-lived, aging or damaged should be replaced in time;
4. After the valve stem is bent or worn, it should be straightened and repaired. If it is seriously damaged, it should be replaced in time;
5. The packing should be installed according to the specified number of turns, the gland should be tightened symmetrically and evenly, and the pressure sleeve should have a preload gap of more than 5mm;
6. The damaged gland, bolt and other parts should be repaired or replaced in time;
7. Observe the operating regulations, except for the impact handwheel, operate at a normal speed and normal force;
8. The gland bolts should be tightened evenly and symmetrically. If the gap between the gland and the stem is too small, the gap should be increased appropriately; if the gap between the gland and the stem is too large, it should be replaced.
