High temperature gear pump due to corrosion caused by mechanical seal failure

High temperature gear pump due to corrosion caused by mechanical seal failure: a) pitting corrosion of the sealing surface, or even penetrate b) due to the tungsten carbide ring and stainless steel seat welding, the use of stainless steel seat easy to produce intergranular corrosion; c) welding metal corrugated Tube, spring, etc. Under the joint action of stress and medium corrosion, the rupture is easy to occur. The mechanical seal due to the high temperature effect fails: a) The thermal crack is a high temperature gear oil pump such as residue pump, refueling pump, , Etc. The most common failure phenomena are radial cracks in the torus due to dry friction, sudden interruption of cooling water, entrance of impurities into the sealing surface and evacuation of the sealing surface. B) Carbonization of graphite is achieved by carbon-graphite rings If the graphite ring exceeds the permissible temperature (generally -105 ~ 250 ℃) in use, the resin will precipitate on the surface of the graphite ring, and the resin near the friction surface will carbonize. When the agent, it will foam and soften, so that the sealing surface leakage increases, the seal failure; c) Auxiliary seals (such as fluorine rubber, ethylene propylene rubber, rubber) exceeds the allowable temperature, it will quickly aging, cracking, Hard missiles now used Flexible graphite has high temperature resistance and good corrosion resistance, but its resilience is poor, and it is easy to be brittle and easily damaged during installation. The sealing failure due to the wear of the sealing face: a) The materials used for the friction pair are poor in wear resistance, friction Coefficient, the end surface than the pressure (including the spring pressure) is too large, will shorten the life of mechanical seals on the commonly used materials, according to the order of wear resistance: silicon carbide - carbon graphite, carbide - carbon graphite , Ceramic - carbon graphite, ceramic sprayed - carbon graphite, silicon nitride ceramic - carbon graphite, high speed steel - carbon graphite, hardfacing carbide - carbon graphite b) For medium containing solid particles, sealing surface into Solid particles are the main reasons leading to failure of the seal.The solid particles into the friction side of the surface from the role of abrasive, severe wear and tear seals failure, reasonable clearance of the sealing surface, and mechanical seal balance, as well as seal the end of the liquid film Flash and so on are the main reasons for the opening of the end surface to make the solid particles enter c) The degree of balance β of the mechanical seal also affects the sealing wear Generally, the balance degree β is about 75% , Operation or equipment itself caused by the error caused by the mechanical seal leakage: 1, due to poor installation, resulting in mechanical seal leakage mainly in the following areas: 1) dynamic and static contact ring surface uneven, bruised during installation, damage; 2) moving, static ring seal size is wrong, damaged or not compressed; 3) moving, stationary ring surface foreign body; 4) moving, static ring V-ring installed in the opposite direction, ) Leakage at the sleeve, seals are not installed or pressing force is not enough; 6) uneven spring force, a single spring is not vertical, the length of the spring varies; 7) sealed chamber end face and the shaft perpendicularity is not enough; 8) There are corrosion points in the sealing ring 2, Equipment in operation, the mechanical seal leaks are mainly due to: 1) the axial displacement of the gear pump impeller exceeds the standard, the shaft vibration occurs periodically and the process operation is not stable, sealed chamber 2) When the friction pair is damaged or deformed and can not run together to cause leakage; 3) Improper selection of seal material, swelling bullet; 4) Large spring steering is wrong; 5) When the device is running Vibration is too large; 6) moving, static ring and the shaft between the formation of scale so that the spring Lost and can not compensate for wear and tear on the sealing surface; 7) Cracking of the sealing ring.