There is a gap in one or two end surfaces. This phenomenon indicates that the distance between the two end surfaces is too large. The common cause of end face separation is the rapid evaporation of imported mechanical sealing medium. For example, water, especially in hot water systems or liquids containing condensed water, expands when it evaporates, thus separating the two ends. Pump cavitation phenomenon coupled with the sealing block may also be the cause of sealing end face gap. In this case, it is not due to the vibration and coupling not caused by this champions league, as this is not enough to make the end face gap. Reducing the temperature of the end face is a common method to prevent the end face from being damaged by the rapid evaporation of the medium. At the same time,   USES the materials with good thermal conductivity is also good, such as with nickel-based carbide and leaching of copper and graphite group, in addition, the balance type mechanical seal, or the use of special corrosion resistant mechanical seal gland from external injection liquid cooling, or directly to the cooling chamber seal, and so on, is very effective to reduce the temperature of the seal face.
  Failure of mechanical seal, friction pair end face often leave very fine radial crack, or radial crack with blister mark, or even crack. This is caused by overheating of the seal, especially ceramic, hard alloy sealing surface easy to produce this kind of damage. Poor lubricity of medium, high overload, high operating temperature, velocity, improper matching material combination, etc., including any kind of factor, or is the superposition of several factors, can produce excessive friction heat, if frictional heat can't send out in time, will generate dyeing mechanical seal of hot crack, resulting in excessive wear and high leakage. Solve the problem of overheating seal, in addition to changing the area of the end face, reduce the load, but also can use static seal and guide the flow sleeve forced cooling circulation fluid guide sealing surface, or open a hydrodynamic groove on the sealing end face to solve. There are many small hot spots and isolated discoloration areas on the friction end face, which indicates that the seal is distorted and distorted by high pressure and heat. For the thermal deformation of the end face, the general calculation method is not allowed, the finite element method should be used to improve the design of the sealing ring.
  The surface spraying hard material seal ring, whether it is spraying Marine mechanical seal ceramic or hard alloy, the surface layer under the thermal load may be its scales or peeling on the substrate. This phenomenon, the seal appears dry friction.

2019-08-12

Thermal load damage to mechanical seal end face material

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