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hunan neptune pump

Failure analysis and solution of mechanical seal of high tem

Source:未知|Popularity:0|release date:2020-12-16 17:15:35
The mechanical seal of high temperature water pump often leaks during operation, which leads to seal failure. The failure causes of mechanical seal of high temperature hot water centrifugal pump are analyzed from the selection of mechanical seal material, end face pressure, cooling water quality, etc., and solutions are proposed to prolong the service life of mechanical seal. The failure analysis of high temperature hot water pump and hot water circulating pump shows that
1. The seal face of moving ring is seriously worn, which may be that the specific pressure PC of the end face is too large, so that the PCV value exceeds the allowable PCV value. Under the condition of constant mechanical seal structure and constant seal medium pressure, only the spring specific pressure PSP determines the end face specific pressure PC, therefore, the seal face specific pressure is larger It may be one of the reasons for the wear of the sealing surface.
2. The cooling water chamber is seriously silted, the cooling water is insufficient or even unable to cool, and the liquid film between the sealing surfaces vaporizes, which results in the deterioration of the sealing surface and the aging of the auxiliary sealing ring. The formation of scale is that the temperature of raw water increases after heating, the soluble Ca (HCO3) 2 and Mg (HCO3) 2 begin to precipitate when heated to about 80 degrees, and Ca (HCO3) 2 and Mg (HCO3) 2 precipitate to form scale on the inner wall.

3. When the temperature of the seal chamber is too high, the seal ring of the moving ring will be thermally softened, which will be together with the shaft sleeve, causing the movable ring unable to float freely along the axial direction, so as to compensate for the wear or displacement of the moving ring. This is the main reason for the large amount of leakage of the shaft seal resulting in splashing. The material of the moving ring is aluminum oxide ceramic, which has high hardness and wear resistance, but poor heat shock resistance and brittleness. If the pump body vibrates or the rotor moves axially, the sealing surface cracks are often caused; in addition, the large temperature difference of the sealing surface is also easy to cause stress concentration and cause seal surface cracks. Therefore, the moving ring is made of tungsten carbide YG6, which has great toughness and rigidity, and good wear resistance. It is suitable for sealing high temperature water medium, reprocessing the moving ring seat and inlaying the moving ring. In order to ensure the sealing performance, based on the failure analysis of the auxiliary sealing ring, the auxiliary sealing ring must have good elasticity and high temperature resistance, and the moving ring seal ring adopts O-type fluororubber seal ring. Because carbon graphite has good self-lubricating property and high-temperature operation ability, it is better to match with cemented carbide, so the static sealing surface still retains carbon graphite, and the static seal ring agrees to use fluororubber.