7 20 Case Study on the Handling of a Fault in a Duty Control Valve
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A little after 9 p.m., Teruaki came back from the small woods. I’m frustrated – why? Because only 5 were photographed tonight, whereas a few days ago dozens could be photographed each night. . . . You know, tonight there are more people with flashlights in the woods than cicadas. . . . Haha, the control room reported that the flow meter at the outlet of the pump in the spray tower showed a value of 780 kg/h with the control valve fully closed; it did not return to zero. Upon arriving on site, it was checked – it was a air-operated valve; when the air supply was cut off and air was released, the valve stem did not move down. I closed the manual valve in front of the process shut-off valve, but the flow meter didn’t change at all,,,, sweat. Then I closed the outlet manual valve as well. . . Still. . . Not at all changed. . . . . . Dizzy. Asked if the process manual valve had internal leakage; the answer was that there was no leakage, let alone leakage in both of them. . . . I suspect there is a problem with the flow meter – it might be clogged or have deposits formed on it. . . Prepare to negotiate a halt in supply for disassembly and inspection. It was found that there was a manual valve at the pump outlet; by shutting the process down further, the value returned to zero. . . . Carefully inspect the pipeline routing; it is suspected that both manual valves in the control valve and process systems are leaking internally. . . After the valve stem is lowered. Adjust the locator once more. . The mechanical one of Samson 3761. . . Open this last manual valve again; close the control valve completely, and the flow meter will not display any flow rate. OK. . Conclusion: The internal components of the control valve suffer from erosion and wear; during maintenance, it is necessary to inspect them to determine whether replacement is required. . Both manual valves before and after the process control valve are leaking internally. . . . It also needs to be replaced. . . .
Some problems seem impossible, yet they actually happen...
Internal leakage in valves often causes significant interference when trying to analyze the causes of accidents during the processing process: L:L:L:L:L
This post was last edited by zhouzurui on 2015-7-21 at 12:35. Does the control valve have a bypass, and is there a leak in the bypass? It is indeed rare for both the inlet and outlet valves to leak internally. Furthermore, if the material is not clean and contains small solid particles, these particles can get stuck inside the control valve spool as well as in the grooves of the two shutters, resulting in the situation where all three valves cannot close properly.
The control valve has no bypass. Indeed, internal leakage in both hand valves is rare; the manufacturing process itself makes it impossible. . . . Hehe. But it leaked so recklessly, and the amount of leakage was quite large.
It seems that valves really can’t be relied on at critical moments
I didn’t take many photos of the cicadas; the meter broke. After carefully checking the cause, it turned out to be the cicadas.