Gate valve is the most common kind of industrial valve, widely used in petroleum, petrochemical, power station, long-distance pipeline and shipbuilding and other industrial fields. As fluid control equipment, gate valve opening and closing member is the gate plate, through the up and down movement of the gate plate, switch open and closed state, so as to achieve the function of cutting off or connecting the medium in the pipeline. If the gate valve leaks, it is easy to bring hidden danger to the pipeline and equipment facilities, and even affect the safety of human life and equipment safety. Understanding the gate valve structure and operating principle can help us operate the gate valve correctly and better grasp the gate valve operating condition. Once the gate valve leakage, the first time to take the correct disposal method to reduce economic losses and reduce the probability of accidents. Gate valve leakage is generally divided into internal leakage and external leakage, resulting in gate valve leakage for a number of reasons, requiring in-depth analysis and research in order to take appropriate disposal measures. The next gate valve supplier will explain the causes of gate valve leakage.
Wedge seal can be divided into two categories, the first hard seal, also known as the metal wedge ring; the second is a soft seal, also known as the composite graphite wedge ring. If the precision of the wedge seal ring is low, it is easy to cause internal leakage of the gate valve.
Valve production and operation process conditions are unstable, the pressure and ambient temperature may change significantly, which makes the seal ring to withstand the larger impact pressure, scouring force and deformation, resulting in the seal ring and the gap between the valve body is growing, resulting in valve leakage.
Staff disassemble the valve for overhaul process, the installation of the wedge seal ring when the sealing surface is not cleaned up, leaving some fine particles and impurities, these fine impurities in the valve operation process may scratch the sealing surface, once the sealing surface to form a penetrating scratch, it will trigger the valve leakage.
In the design of the wedge seal ring need to pay more attention to the strength and corrosion resistance of the seal ring, the surface hardness of the seal ring to be smaller than the hardness of the valve cover sealing layer, but also in line with the role of external conditions can occur under the plastic deformation, the media may also corrode the wedge seal ring during prolonged operation, thus triggering the gate valve leakage.
Gate valve switch is controlled by the actuator, the actuator relies on liquid, gas, electricity or other energy and through the motor, cylinder or other devices will be transformed into a driving role to drive the valve to the fully open or fully closed position. Actuator open or close is not in place, will lead to the gate valve can not be fully open or closed, resulting in internal leakage of the valve.
Cast valve body often casting defects, such as porosity, slag, cracks, sand eyes, etc., if these defects are not found in the plant, or found without taking the correct repair measures, the valve will leak in the process of field use.
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