Solution to the problem of metal bellows sealing
Metal corrugated pipe is a kind of multi-functional thin-walled shell parts with transverse bellows and flexibility, which can produce axial, angular, lateral and combined displacements under the action of external forces and torques. It is widely used in machinery, aerospace, petrochemical, electric power, automobile, ship and nuclear industries.
The usage of metal bellows mechanical seal was fully investigated by bellows manufacturers, and the failure seal was fully analyzed from the aspects of structural design, material and auxiliary system layout, and three major problems were found.
1. Sealing friction pair end face wear seriously. Due to the high viscosity and poor fluidity of residual oil, and the residual oil medium contains granular and powdery coking materials, there are inevitably coking materials around the friction pair, which is quite harmful to the friction pair. Once the coking material enters the sealing end face, it will soon strain the sealing end face and produce scratches due to the high-speed rotation of the friction pair. With the continuous entry of polymer and impurity particles into the friction end face, the sealing surface will be gradually worn away, finally resulting in sealing leakage failure.
2. Corrugated Steel Pipe assembly loses its elasticity. In the actual use process, in order to achieve the sealing function in high temperature, high pressure state, contact bellows seal generally use a large amount of compression, so that the sealing end face ratio pressure will be greatly increased, friction pair of end face wear serious, and generate a lot of friction heat. If friction heat cannot be taken away in time, under the long-term action of high temperature, the bellows stiffness or elasticity will gradually reduce or even disappear, that is, the bullet is lost, and the higher the temperature, the greater the load, the faster the bullet is lost. If the bellows lose their elasticity, the sealing end face is opened immediately under the medium pressure, that is, a large number of leakage occurs.
3. Large consumption of flushing oil and cooling water. In order to prevent the temperature of sealing parts from rising and causing coking, measures such as external flushing and cooling must be adopted to reduce the friction temperature rise, prevent coking, hot cracking and aging and lead to sealing failure. Therefore, a large amount of flushing oil and cooling water must be consumed, resulting in high operating costs.
Some domestic corrugated pipe factory has used the rubber ring 0 outsourcing one or two layers of tetrafluoroethylene, this structure on the one hand, solves the tetrafluoroethylene 0 ring elasticity bad problems, at the same time solve the problem of deformation of the rubber seal ring 0, aging, to this kind of ring, we conducted on pumping test, the result is good.
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