Pneumatic ball valve sealing damaged cause analysis

in high temperature and high pressure pneumatic ball valve ( 。 MPa saturated steam) , the trial process, and found a seal seat is damaged, the damaged seal seat, as shown. Through careful observation, found damaged media imported seal seat, the damaged part is the same, and the outlet seal intact. Want to make sure that in the process of seal seat in the process of the pneumatic valve opened or closed damaged, special points ball was tested. First of all, pneumatic ball valve is closed, resulting in saturated steam. MPa, preheating minutes, open the pneumatic valve, then check that the seal damaged; Then pneumatic ball valve open, resulting in saturated steam. MPa, preheat minutes later, close the pneumatic valve, then check that the seal seat is damaged, the results of two test of air inlet seal damage phenomenon. Due to the floating ball pneumatic valve sealing pressure of the medium under the principle of pneumatic valve structure, the pressure at the outlet seal seat in a certain range of displacement, so as to ensure the seal, so the import seal seat is damaged, not affect the sealing performance, the ball has certain concealment. When the pneumatic valve opening and closing action a few times, imports will partially damaged, the damage loss decrease in seal seat. Damage the seal seat
the damaged parts, on the basis of the consistency of the sealing seat and the opening and closing ceremonies will take place on the import side sealing damaged the same parts, pneumatic valve opening and closing the detailed analysis process.
as in figure a, when the pneumatic valve closing, in the medium pressure, in certain pressure displacement caused by the ball in the outlet seal seat, show, by the outlet seal seat, to ensure that the pneumatic valve seal. Air inlet seal seat backward areas, reduced the seal than the closet, into the medium pressure seal at the bottom of the seat, under pressure, with all the ball sealing surface contact, and then seal seat will not damage; When the pneumatic ball valve and open operation ( See figure b) , imported pneumatic valve A and B cavity central cavity will form A flow channel, to generate differential pressure, delta p when non-contact flow and the pneumatic ball valve seat seat, this part will lose support under pressure, bending deformation in the medium term. When the ball continue to rotate, seal seat edge bending part of the channel will be crushed and sealing performance.
pneumatic valve closing process roughly the same. As shown in figure a, when the pneumatic valve opens, the load and nonmetal sealing seat ( Much bigger non-metallic expansion ratio coefficient of expansion coefficient of metal) Thermal expansion effect, pneumatic ball valve assembly, so, could not enter the pneumatic valve cavity in the channel B, so the central channel and pneumatic valve cavity pressure difference delta P, B but in this time of the sealing pneumatic valve seat sealing surface contact with all not deformation, sealed ball; When the pneumatic ball valve closed operation ( As shown in figure b) , sphere and B channels have a cavity in the process of pressure balance, from entering the cavity channel, B with pneumatic valve seat in the flow when in contact with the ball, seat of the loss of support media, under the pressure of the part, the bending deformation. This distortion can occur in both ICONS on the may also occur in the lower left corner and the bottom right hand corner, entry seal seat is damaged, because when continue to close the pneumatic valves to figure c, the cavity between the location of the cavity, and B, B and c of the chamber between the delta P, A and B of the chamber between the imported pneumatic seat delta P, the bending deformation is relatively serious, pressure difference and between B and c cavity pressure difference cavity, the deformation of the seal seat is fixed, when turning, import the edges of the curved fairway seal seat will be part of the grinding ball, seal, and the pressure difference between the export will not be damaged.