What are the effects of overheating when the mechanical seal is used

What are the effects of overheating when the mechanical seal is used

21/11/16 11:15:11

During the use of mechanical seals, if they are used for a long time, they are prone to overheating. In this regard, the next step is to understand the impact of the overheating of the equipment, so as to better use the equipment.

According to different working conditions and medium properties, there are high temperature resistant, low temperature resistant seals, high pressure resistant, corrosion resistant seals, particle medium resistant seals and seals suitable for light hydrocarbon medium that is easy to vaporize, etc., and should be used according to different purposes. Choose seals of different construction types and materials.

There is a gap on one or both end faces. This phenomenon indicates that the distance between the two end faces is too large, and when the two end faces are tightly closed, a gap will be generated. A common cause of end face separation is flash evaporation of inlet seal media. For example, water, especially in hot water systems or liquids containing condensed water, expands as it evaporates, thereby separating the ends. Pump cavitation combined with clogged seals may also be the cause of chipped seal faces. In this case, it was not due to vibration and misalignment of the coupling, as this was not enough to notch the end face.

Reducing the temperature of the end face is a common method to prevent the end face from being damaged due to the rapid evaporation of the medium. At the same time, it is also beneficial to use materials with good thermal conductivity, such as nickel-based carbide and copper-impregnated graphite, in addition, use a balanced mechanical seal, or use a special corrosion-resistant seal gland to inject liquid from the outside for cooling , or directly cool the seal in the cavity, etc., are very effective in reducing the temperature of the sealing end face.

For failed seals, very thin radial cracks are often left on the end faces of the friction pair, or radial cracks combined with blister marks, or even cracks. This is caused by overheating of the seal, especially the ceramic and hard alloy sealing surfaces are prone to such damage. Poor medium lubricity, overload, high operating temperature, high line speed, improper combination of matching materials, etc., any one of these factors, or the superposition of several factors, can generate excessive frictional heat. If the frictional heat cannot be dissipated in time, There will be dyeing and finishing mechanical seal thermal cracks, resulting in excessive wear and high leakage.

To solve the problem of seal overheating, in addition to changing the area of ​​the end face and reducing the load, it can also be solved by using a static seal and adding a guide sleeve to force the cooling circulating fluid to guide the sealing face, or opening a fluid power groove on the seal end face. There are many small hot spots and isolated discoloration areas on the friction end face, which shows that the seal is deformed and distorted under the influence of high pressure and heat. For the thermal deformation of the end face, the general calculation method is not allowed, and the finite element method should be used for calculation in order to improve the design of the sealing ring.