WCB Triple Eccentric Lug Butterfly Valve Pindee Valve

Pindee Valve is a branch from PINDEE INDUSTRIAL which manufacture WCB Triple Eccentric Lug Butterfly Valve .In a nuclear power plant, the pneumatic butterfly valve fails to open many times during the operation of the unit (the operation specification requires the opening time of the valve to be ≤120 s). At the beginning of valve opening, there is no action within 2 ~ 3 min. After the valve starts to operate, it can reach the fully open state within 30 ~ 40 s, but the valve is jammed at 20% ~ 40% opening. After testing, all parts of the valve run well, and there are no body faults such as jams and damage. In order to completely eliminate the valve opening delay and jam failure, a series of analyses, calculations and related tests were carried out on the valve and system, to find out the causes of valve failure, and to formulate the valve improvement scheme.Welcome to Pindee Valve,send us an inquiry request to our email address:sales@pindee.com

Structural property
The valve is composed of a rubber-lined butterfly valve and a pneumatic device (Figure 1). A rubber-lined butterfly valve is composed of the valve body, butterfly plate, valve seat and valve stem, etc. The valve is sealed by the interference between the butterfly plate and the rubber valve seat. The pneumatic device is a fork-type single-acting cylinder, with air intake at the cylinder side, the piston pushing the fork to rotate, the output torque closing the valve, and compressing the spring to store energy. The air intake at the cylinder side is stopped, and the spring is reset, pushing the piston to drive the fork to rotate, and the output torque opens the valve. The butterfly valve has a nominal size of DN600 and a working pressure of 1. 2MPa.

Increase rod mechanism of the valve stem

A pull rod mechanism is added to the upper and lower valve stems to reduce the influence of system pressure on the offset of the upper and lower valve stems, improve the coaxiality of the upper and lower valve stems, and eliminate the blockage in the middle position caused by the misalignment of the valve stems. Eccentric Lug Butterfly Valve,A small ball structure is designed at the joint between the lower valve stem and the butterfly plate, which can position and prevent the lower valve stem and the butterfly plate from rotating, and the upper and lower valve stems can rotate synchronously to ensure that the threads at the joint between the upper and lower valve stems will not loosen.

Cylinder improvement

Considering the space limitation of the site, only the piston cylinder and the matched spring are improved. WCB Triple WCB Triple Eccentric Lug Butterfly Valve. After calculation, the cylinder diameter D = 450 mm, and the effective number of turns of the outer spring is 10. 5, the total number of turns 12, the full compression pressure 20. 1 kN, the effective number of turns of the innerspring 10. 5, the total number of turns 12, and the full compression pressure 20. 2 kN are selected. After the improvement, the maximum opening torque of the cylinder increases by 1. 4 times, reaching 7 550 N m, and the designed safety factor reaches 1. 75, which can avoid the valve jam caused by turbulence, vibration and bearing wear.

Conclusion

After the improvement of the rubber-lined butterfly valve, after field application, the 120s delay in the opening of the valve completely disappeared, the valve could be opened within 30-50 s, and the 20% ~ 40% opening jam completely disappeared, and the valve was verified as qualified. After replacing a large number of similar valves in the system, its performance is good, and there is no jam or delay in opening, which guarantees the normal operation of the system.