Reasons for wear of the control valve stem
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This is the valve stem for a DN80 control valve, featuring bellows sealing and designed for use with high-temperature heat transfer oil in control applications. Half a year after it was put into use, severe lagging was observed; this is what it looked like after taking it apart. Is it due to insufficient manufacturing precision or deformation caused by high temperatures? Visually appears to be 304 material, temperature 270
It is recommended to check whether the hardness difference between the valve stem and the guide sleeve is appropriate The valve stem should not be worn to this extent if its hardness is appropriate.
Personally, I think it’s still a matter of quality – the quality of processing, the quality of the materials, and so on...
Is the adjustment frequent? What is the operating pressure of the valve? What is the differential pressure?
It’s still likely that the operating conditions are not suitable. Replacing it with a cage valve should improve things a lot
The guide sleeve design is unreasonable. The valve stem experiences vibratory friction within the guide. It doesn’t affect usage, so it can be ignored
Poor design, inappropriate material selection
After half a year of use, the materials used are of inferior quality; the quality of the materials is poor
To be honest, this type of pilot-operated single-seat valve suffers from quite a few sticking problems; an imbalance in the valve spool can cause this issue, especially at low opening angles. Additionally, impurities adhering to the guide and valve stem can also cause sticking, which in turn leads to surface damage
Check whether the material meets the requirements, as well as whether there is excessive pressure difference causing vibration in the valve; uneven wear can also be observed, and the valve stem may deform due to high temperatures