Abstract: In some rely on self-closing valve hammer the station, butterfly operation a few years later, appeared in the closing process less than fully closed position of valve related failures. For this analysis, a reliable valve automatically close the program, the program not only ensures the normal valve closure on the station’s maintenance, operation provides security, and better protect the valve spindle and bearing, extend the butterfly valve of use.
Key words: butterfly valve; off failure; cause analysis; treatment
1 Overview fault butterfly valve
Qinshan station using PDF130-WZ-280 butterfly valve, the Department of horizontal double plate valve structure. Valve assembly including valve, valve, working the main seal, bearing, arm, relay device, locking devices, hammer and bypass valve. Valve body is cast with the overall structure of welded, ring contact of the body and the work of stainless steel, extended seal life and improve sealing performance. Valve seal located in the downstream side of the sealing surface inclined structure, which has good sealing performance. 8 the bottom of the body as a fixed body with a bolt, can bear the relay device and moving upward thrust acting on the valve on the water up the pitch, but can not afford the water valve is fully closed when the thrust. To increase the water valve turned off when moving from the closing torque, according to the bias valve and valve design, the geometric center and center of rotation offset 50mm, increase the reliability of closure. Main valve rubber seal on the valve shaped by the surrounding solid, and the compression screw with a clamping ring secured to the valve, in order to ensure the seals and adjustable and adjusted position, with locking screws to be fixed. 40Cr forged steel valve shaft material, shaft sealing contact with the bearing and chrome plated Protection Agency, and the valve with a fixed cylindrical pin inserted. Sleeve bearing made of steel and copper composition tile, copper tile material is cast aluminum bronze (ZCuAl1OFe3), shaft seal ring with U-shaped support ring, sealing force can be adjustable, easy to replace.
The valve arrangement of 2 sets of 200mm diameter straight cylinder sway servomotor servomotor piston rod through the arm and the valve shaft, chrome plated piston rod. Q piston and cylinder with O-ring seal with PTFE composite seals; Sec servomotor cylinder shut-off device and the throttle has a buffer structure, the external high pressure hose connection.
Control system. Open the butterfly valve hydraulic control unit with FYZ oil supply, to promote the relay device to fully open the valve and the hammer after the use of hydraulic lock spindle, spindle lock oil source from the governor hydraulic device. When the unit normal accident or need to stop, switch lock spindle oil source was torn off valve is configured on its own two mallets (the 3.5 t) and the hydraulic action to the valve is fully closed, cutting off water flow and protection play unit effect.
2 Fault phenomena
Butterfly Qinshan station to vote in March 2000 were running, running to March 2002, found that the process of closing the valve when the valve closed until about 95% of full stroke, the butterfly arm (hammer) stop falling, butterfly can not reach the fully closed position themselves. This valve can only open and close two contradictory positions, valve position in a volatile state, resulting in a large amount of leakage, caused by strong noise, to the station’s maintenance operation has brought greater security risks.
3 Analysis of the causes
3.1 Tubing Road area
This phenomenon may be due to poor discharge of oil return line off the side relay device caused the oil has not drained the oil chamber, the resulting servomotor piston can not return to fully closed position, leading to the whereabouts of butterfly arm can not reach the maximum stroke, caused by valve not fully closed off.
In this connection, the operating oil pipeline check valves for the oil pipeline decomposition checks to ensure smooth operation of oil pipeline.
3.2 Relay structure
In the closing process to reduce the servomotor servomotor impact of oil at the bottom of the piston speed and pressure in the cylinder with Sec servomotor operation shut-off device, that is throttling the buffer structure.
Throttling of the buffer structure servomotor servomotor throttle cleaning and adjustment, increase the throttle opening, so back to the larger flow of oil, throttle before and after the pressure becomes smaller, is conducive to the servomotor the whereabouts of the piston. Also, check that the surface of the servomotor piston rod chrome plating intact, no signs of rust jam.
The above two methods, no obvious effect, butterfly valve cannot reach sexual position of reason and operating system (operating pipeline and relay device device).
After this article written: “Butterfly valve closed failure analysis and processing method (Part II)“