General mechanical seal failure analysis Seal common cause, usually through the process of using the experience obtained in the past.
a. working gas sealed shock (splash and sputtering).
b. sealing leaks and Grand icing.
c. steady drip sealing surface.
d. sealing work screaming.
e. Grand Central outside a graphite powder accumulation.
f. pump and (or) axis vibration.
g. sealing short life.
Typical mechanical seal failure
General mechanical seal failure analysis Seal common cause, usually through the process of using the experience obtained in the past.
a. working gas sealed shock (splash and sputtering).
b. sealing leaks and Grand icing.
c. steady drip sealing surface.
d. sealing work screaming.
e. Grand Central outside a graphite powder accumulation.
f. pump and (or) axis vibration.
g. sealing short life.
Vaporization (flash)
When the sealing surface friction heat concentration, the face took place between the local film boiling.
When sealing pronunciation or to take gas (intermittent shock). Static ring bitten loss, generate comet-like texture process leads to a narrow ring outer cutting edge. The hard part of thermal cracking. Face in at the edge of a graphite dust accumulation.
Corrective measures to check seal design parameters; to improve circulation.
Dry run
Face between the liquid inadequate or no liquid.
Static symptoms of serious wear and ring groove. Traces of hard polished surface rings, or radial cracks (thermal cracking) and discoloration. Aprons sclerosis. Graphite ring with disc-shaped grooves.
Corrective measures to use balanced seal; use of high thermal conductivity of rigid material; check the exhaust situation; improve circulation.
Pimple scar
Face between the high viscosity fluid shear stress exceeds the fracture strength of graphite. When the pump stops, due to increased temperature decreases the viscosity of the liquid to the pump restart problems.
Symptoms of carbon graphite particles from the end prolapse; hard ring with polishing marks; in the small gap in the residual graphite particles.
Corrective measures to check the loop condition; with 15 ~ 30min of steam preheat or ※ low pressure steam heat.
Abrasive wear
Medium containing the grinding of solid particles.
Residual symptoms or accumulation of solid particles and small gaps, etc. in the end.
Wear-resistant material used as a corrective measure end; to improve cycling conditions: rotating liquid separator and external clean flush ... ...
Face deformation
When pump starts, the seal leakage and leakage over time. Will end on the platform light research, there are signs of deformation.
Corrective measures to natural aging deformation, re-grinding; assembled properly, carefully re-assemble; pump on the poor, bearing damage, adjust the pump.
Coke
High-temperature coking hydrocarbon failure often occurs. Hours of film leakage, seal the air side of the coking tendency there, it will obstruct the end of the following, and cause wear face.
When concentration of solid particles in the air side of the sliding parts.
Corrective measures to change the soft end to rigid end; with hot water, steam or solvent as a permanent quenching.
Slip diameter damage
Vibration and corrosion in the case, so follow the face of loss. Micro wear and electrochemical corrosion.
When auxiliary slip ring diameter, on the slip near the serious pitting and corrosion (corrosion oxide layer can not form).
Corrective measures to check the pump and motor to the neutral, to eliminate vibration, bearing failure and shaft is bent; slip diameter hardened or sprayed ceramic.
Spring deformation and fracture
Rely on spring torque transfer in a single spring seal.
When spring section Department has radial cracks. Spring and sleeve ends have the marks and because of the spring slipping the left necking.
Corrective measures to check the direction of rotation is correct.
※ broken bellows
Welding mushrooms, heat affected zone, the matrix.
Symptoms: welding broken parts of mushrooms, are welding quality. Heat affected zone fracture site is the first, because this part of the stress concentration zone, alternating load induced fatigue damage of sealing work. 316L austenitic stainless steel such as heat-affected zone in welding high temperature, the hardness decreased, leading to damage in the loading. Wave plate matrix fracture rare, and only appears in the austenite stress corrosion. Bellows in stamping, welding and other work necessary during the residual stress, in the event of halogen ions will occur along the stress direction corrosion, resulting in destruction of material strength decreases.
Corrective measures: to improve the welding quality. Change the waveform, the stress range and dispersed to avoid over-concentrated in the heat affected zone. With martensitic steel products, such as hardness, heat affected zone change material.
Avoid stress corrosion, should select the appropriate material.
Graphite ring (or ceramic) fracture
PTFE o-ring friction is small, stationary ring with the ring rotation, after contact with pins broken.
When the pin groove Department graphite ring cracking or breaking one.
Corrective measures to make the pin set; use other types of seals or static ring.
o-ring overheating
As the heat transfer is usually negative end result.
When rubber ring hardening, cracking. PTFE blue or black. Close to the seal faces the most serious situation.
Corrective measures to check seal design; check and improve circulation.
o-ring extrusion
o-ring part is forced through a small gap. Assembly or assembly of components for excessive force, or the seal gap is too large.
When o-ring has been cut or torn skin.
Corrective measures to check the assembly method.
o-ring erosion, swelling
When inappropriate material selection occurs when swelling, fracture, deformation faults.
Corrective action based on the actual condition to re-select the material.
Graphite erosion (components)
When fluid pressure is too large or contains grinding particles.
When the entrance is in the fluid component of the Department has erosion pits.
Corrective measures to reduce the fluid pressure; by rotating liquid separator.
Find time
System pressure or the seal faces volatile place to produce cavitation
Symptoms: Department dregs round face, round Zhou Chengbo striated, 0 laps out of, away from the place of static ring.
Corrective Action: change the system operation process, increase the flushing volume
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