Chemical plant butterfly valve switch not in place case analysis introduction

1 Overview

The type of regulating valve is butterfly valve, the specification is DN100, PN2.0MPa.


2 There is a problem

The regulating valve is not in place during the switching process, that is to say, the rotation of the butterfly valve cannot meet the requirement of 0°-90°. The regulating valve is a two-position air opening valve. During the joint school, it was found that the fully open position did not reach 90°, and the adjustment was made online. The limit bolts at both ends of the actuator were rotated outward to adjust, and the valve opening degree satisfies 90°. However, the valve did not return to the closed position when it was closed.


3 Reason analysis

When the actuator is adjusted, it is adjusted according to the traditional piston actuator. That is to say, the limit bolt of the conventional piston actuator can only limit the distance of the piston to the outward displacement. At the same time, it has not been adjusted, but it is not known that FLOWSERVE has improved the limit form of the actuator.


    4 treatment methods and results

Pass the compressed air from the P2 end to the actuator to open the valve, then rotate the left bolt inward, then cut off the P2 end air supply, and open the compressed air from the P1 end to the actuator to close the regulator. Check the adjusted angle. Whether the requirements are met.


5 Summary of experience

The lack of understanding of the structural form leads to the phenomenon that the valve cannot be fully closed. However, this inspection found that this type of actuator can be shown on the soft-seal butterfly valve because the soft seal, especially the rubber-sealed coaxial butterfly valve, when it is closed, reaches 0°, then it is turned on. Will open the beating. In fact, the soft sealing butterfly valve can ensure its sealing performance when it does not reach 0° during operation. The opening jump can be eliminated by limiting the actuator. In addition, if the cylinder piston is to be disassembled during maintenance, it must be marked. Do not install the pistons at both ends. Otherwise, the rotation direction of the shaft inside the cylinder will change.