What can cause a control valve or on/off valve to fail to close properly or to not seal tightly?
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What can cause a control valve or on/off valve to fail to close properly or to not seal tightly?
There are foreign objects in the medium; solid particles are lodged between the valve disc and the valve seat. The valve stem is not properly connected to the valve disc, causing the valve disc to be misaligned and fail to make tight contact with the valve seat.
If it’s a control valve, it’s much more complicated. The so-called control valves are mostly valves of the globe type; many of these valves are controlled pneumatically or electrically, while some are operated manually. So there are many aspects involved; it’s better to be more specific, to address each issue individually, and to share a video or a description of the problems that need to be solved for reference.
The gas source pressure is below 0.4–0.6 MPa; there are issues with the 4–20mA signal transmission, there are foreign objects in the pipeline, and the control valve has not been tested individually. Your question is too broad – there could be issues with the process engineering aspect, the instrumentation aspect, or the valves themselves
That’s a great question of yours – just take it apart and have a look, and you’ll know
The closing torque is low, resulting in poor sealing. There are countless reasons for torque: 1, 2, 3, …!
There are three reasons why a control valve or on/off valve cannot be closed properly or tightly: 1. Issues with the valve itself； 2. Signal circuit issues ； 3. Energy (power source, gas source, hydraulic source) issues. There are many reasons for each aspect.