1. Diagnose the cause of the leak
First, it is necessary to accurately diagnose the cause of the leak. Leakage may be caused by a variety of factors, such as wear of the sealing surface, aging of the material, improper installation, operating errors or corrosion of the medium. The source of the leak can be quickly locked by using detection tools and methods, such as ultrasonic leak detectors, visual inspections and pressure tests, to provide a strong basis for subsequent repairs.
2. Solutions for different leaking parts
1. Leakage caused by the detachment of the closing part
Reason: Poor operation causes the closing part to get stuck or exceed the upper dead center, and the connection is damaged and broken; the material of the connecting part is not selected, which cannot withstand the corrosion of the medium and mechanical wear.
Solution: Operate the valve correctly to avoid excessive force that causes the closing part to get stuck or damaged; regularly check whether the connection between the closing part and the valve stem is firm. If there is corrosion or wear, the connecting part should be replaced in time; select a connecting part material with good corrosion resistance and wear resistance.
2. Leakage at the sealing ring connection
Reason: The sealing ring is not rolled tightly; the welding quality of the sealing ring and the body is poor; the threads and screws of the sealing ring are loose or corroded.
Solution: Use adhesive to fix the rolled part of the sealing ring; repair and re-weld the poorly welded parts; replace corroded or damaged threads and screws in time; re-weld the sealing ring joints according to the specifications.
3. Leakage of valve body and valve cover
Reason: The casting quality of cast iron parts is not high, and there are defects such as sand holes, loose structures, slag inclusions; cold cracking; poor welding, slag inclusions, unwelded, stress cracks and other defects; the valve is damaged after being hit by heavy objects.
Solution: Improve the casting quality and conduct strength tests before installation; insulate or heat-treat valves with low temperatures, and remove water from valves that are out of use; weld according to the welding operating procedures, and conduct flaw detection and strength tests; it is forbidden to push and place heavy objects on the valve, and avoid hitting cast iron and non-metallic valves with hammers.
4. Leakage of sealing surface
Reason: The sealing surface is not ground flat; the connection between the valve stem and the closing part is suspended, incorrect or worn; the valve stem is bent or assembled incorrectly; the sealing surface material is improperly selected.
Solution: Select the gasket material and type according to the working conditions; carefully adjust the valve to ensure smooth operation; tighten the bolts evenly and symmetrically, and use a torque wrench to ensure that the preload meets the requirements; repair, grind and color the static sealing surface to ensure that it meets the relevant requirements; pay attention to cleaning when installing the gasket to avoid the gasket falling to the ground.
5. Leakage at the packing
Reason: Improper selection of packing; incorrect installation of packing; aging of packing; low precision of valve stem; damage to components such as gland and bolts.
Solution: Select the appropriate packing material and type according to the working conditions; correctly install the packing according to the specifications; replace the aged and damaged packing in time; straighten, repair or replace the bent and worn valve stem; the damaged gland, bolts and other components should be repaired or replaced in time; comply with the operating procedures and operate the valve with uniform speed and normal force.
III. Preventive measures
1. Regular inspection and maintenance: formulate a reasonable maintenance plan according to the frequency of use of the valve and the working environment. Including cleaning the inner and outer surfaces of the valve, checking whether the fasteners are loose, and lubricating the transmission parts. Through scientific maintenance, potential problems can be discovered and dealt with in time, extending the service life of the valve.
2. Select high-quality valves: To fundamentally reduce the risk of valve leakage, high-quality valve products need to be selected. From material selection, structural design to production process, valve products that have been strictly controlled can ensure the best performance. Correct operation and installation: Follow the operating procedures and operate the valve correctly. During the installation process, pay attention to the installation position and direction of the valve to ensure that the valve can be opened and closed normally. At the same time, avoid applying excessive force on the valve or hitting the valve.