Valve handwheel can rotate, but the trip does not make any changes, I ask, what are the reasons for this ah? Or, specifically, what are the reasons? Positioner, mechanical, pneumatic, all normal
There should be a fracture between the link between the stem and the valve.
What type of valve? Pneumatic valve? Send a picture to see.
This kind of thing can not be seen on the spot. The connection between the stem and handwheel is loose. Hand wheel idle
If the stem is rotated, it may be: 1, the lifting nut damage; 2, the stem broken,
