Long-distance pipeline is called long-distance pipeline, long-distance pipeline valves used on the pipeline is called pipeline valves, ball valves, gate valves, check valves, plug valves, is a kind of pipeline transportation to meet the special requirements of the special features of the special valves.
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the internal leakage problem and its cause analysis
1 improper storage caused by the ball and seat damage Ordered ball valves are generally not immediately after the arrival of the installation, if the unpacking inspection, not to take appropriate protective measures or to restore the manufacturer's factory packaging status, may cause the valve ball corrosion, and even lead to serious ball surface plating off, directly affecting the ball's abrasion resistance and corrosion resistance, shortening the service life of the valve.
2 residual hard impurities caused by the valve ball and valve seat damage Long-distance pipeline line is very long, despite the adoption of a segmented ball pressure test pipe, but in the water coupled with the initial period of oil, but still can not guarantee that the pipeline impurities have been all cleaned up, these hard impurities (such as electrode head, welding slag, welding spatter, etc.) follow the water or oil in the operation of the ball valve, once in the switching process of intermingled with the sealing surface of the sphere and the valve seat Once in the switching process in the ball sealing surface and the valve seat, it will damage the metal valve seat and soft seat, and even cause scratches on the surface of the ball. For example, the Southwest pipeline Anshun sub-transmission pumping station to collect the ball cylinder before the ball valve in operation, due to the hard inlaid valve seat sealing surface, resulting in the valve seat on the main seal (soft seal) two serious wear.
3 improper operation caused by the valve seat and ball damage switching ball valve is not allowed as a regulating ball valve, if the operation of the switching ball valve used as a regulating valve, the valve is placed in a half-open and half-closed state, then the valve seat will be subjected to direct impurities entrained in the fluid scouring, rapidly exacerbate the wear and tear of the valve seat, the fluid entrained in the hard impurities will be directly undermined the valve sealing surface, resulting in the valve to appear leakage problems.
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over-torque problem and its cause analysis
1. Valve theoretical calculation of the torque; on the other hand, the actuator output torque of the safety coefficient selection is small, resulting in the opening and closing torque required by the ball valve and the actuator output torque is far from the maximum output torque provided by the actuator is not enough to open the ball valve operated under the full differential pressure, thus causing the valve to appear over-torque faults.
2. Impurities increase the valve switching operating torque The large particles of hard impurities in the pipeline can not only damage the valve seat and valve ball, but also impede the rotation of the ball, increasing friction, sharply increasing the opening and closing torque of the valve. In addition, if a large number of small-diameter impurities in the valve body, will also increase the ball valve operating torque. Southwest pipeline Lin station over the station ball valve (bit number 02MOV013), in the full differential pressure under the over-torque problem, can not be opened, respectively, the torque required for the body of the ball valve and the actuator's output torque was detected by the test results found that the ball valve over-torque is mainly due to the actual operating torque of the ball valve body is greater than the design of the operating torque, and at the same time, the electric actuator output torque is much smaller than the output torque of the technical requirements. At the same time, the output torque of the electric actuator is much smaller than the output torque of the technical requirements, so the electric actuator is unable to control the ball valve under large differential pressure, and the problem of over-torque occurs. In addition, if the ball valve is not used for a long time, the operating torque of the ball valve is greater than the torque required for regular operation of the ball valve (after opening and closing the ball valve for several times, the operating torque of the ball valve gradually decreases and basically tends to stabilize).
