Q
Cause analysis and treatment of mechanical seal leakage
A
Cause analysis and treatment of mechanical seal leakage
1.Leak when static pressure test
(1) when the sealing end face is installed, it is damaged, deformed and damaged.
(2) when the sealing end face is installed, the cleaning is not clean, and the particles are covered with impurities.
(3) the sealing face is not compressed due to the loosening of the positioning screw or the tightening of the gland (the stationary ring assembly is a pressure plate).
(4) the accuracy of the machine and equipment is not enough, so that the sealing surface is not completely fit.
(5) the static and dynamic ring seal is not pressed or compressed enough or damaged.
(6) the static and dynamic ring V type sealing ring is mounted in reverse direction.
(7) if the shaft is leaking, the sealing ring of the sleeve is not pressed or compressed or damaged when assembled. Processing method: assembly inspection and cleaning shall be strengthened and assembly shall be carried out in strict accordance with technical requirements.
2.periodic or paroxysmal leakage
(1) the axial thrust of the rotor assembly is too large. Processing method: adjust thrust bearing, so that the thrust of the shaft is not greater than 0.25mm.
(2) periodic vibration of rotor assembly. How to deal with it: find out the cause and eliminate it.
(3) the pressure in the sealing cavity often varies greatly. Treatment method: stable process conditions.
3.Frequent leaks
(1) frequent leakage due to defects in the end face of the seal.
①The amount of spring compression (mechanical seal compression) is too small.
②The spring is too big to compress and the graphite ring is cracked.
③The sealing end width is too small and the sealing effect is poor. Treatment method: increasing the sealing end width and increasing the spring force.
④The floating performance of the compensating seal ring is too poor (the seal ring is too hard or too long, the hardening or compression is too small, and the clearance of the sealing ring is too small). Treatment method: the gap of the compensating sealing ring is too small, and the gap of the compensating sealing ring is increased.
⑤Seam inlaid or bonded dynamic and static ring leakage (insert process, residual deformation; uneven material; adhesive uneven deformation).
⑥Damage or cracks occurred in the moving or stationary ring.
⑦The sealing face is seriously worn out and the compensation capability disappears.
⑧Dynamic and static seal face deformation (end by spring force is too large, the increase of friction and thermal deformation or partial wear; sealing parts of the irrational structure, insufficient strength, deformation; stress due to improper processing, sealing parts have residual deformation; installation force caused by uneven deformation). Handling: replace defective or damaged sealing rings.
⑨The vertical deviation of the end of the ring and the center of the shaft is too large, and the relative degree of parallelism of the end face of the moving and static ring is too large. Treatment method: adjust the sealing face.
(2) recurrent leakage caused by auxiliary sealing ring.
①The material of the sealing ring is wrong, and the wear resistance, corrosion resistance, temperature resistance and aging resistance are too bad, so that the deformation, hardening, rupture, dissolution and so on occur too early.
②O type sealing ring of the amount of compression is wrong, too large when it is easy to install broken; too small sealing effect is not good.
③Install the sealing ring of the shaft (or shaft sleeve), sealed end cap and sealing cavity, in the O sealing ring to promote the surface of burr, chamfer is not smooth or round corner is not big enough. Processing method: the burr and unsmooth chamfer should be properly trimmed and smooth, arc and chamfer should be properly increased and trimmed smooth.
④O type sealing ring breaks, breaks, breaks, rolls or distorts. Processing method: pay attention to cleaning rubber ring, do not use gasoline, kerosene; when assembling sealing ring, pay attention to straighten out.
(3) leakage due to spring defects.
①Spring end deviation.
②Multi spring type mechanical seal, the free height difference between the springs is too large.
(4) leakage caused by other parts, such as transmission, tight setting and thrust parts, is of poor quality or loose, causing leakage.
(5) leakage caused by rotor, such as leakage caused by rotor vibration.
(6) because of the frequent leakage caused by the auxiliary mechanism of the mechanical seal, such as the flow of the coolant is too small or too large, the pressure is too small or too large, the direction or position of the liquid is not correct, the quality of the liquid is poor and the impurity is in the liquid.
(7) due to the media problems caused by frequent leakage.
①The medium contains suspended particles or crystals, which are blocked between the moving ring and the shaft, the spring, the spring and the spring seat, etc., so that the compensating sealing ring can not float, and the buffering function is not compensated.
②The suspended particles or crystals in the medium are blocked between the sealing ends, so that the sealing ends are not jointed properly and are quickly worn out. Processing method: first open the flushing cooling valve before driving, over a period of time and then turning, driving, open washing cooling liquid; increasing medium entrance temperature; improve medium filtration and separation effect etc...

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