Analysis of mechanical seal failure of centrifugal pump

centrifugal pump shutdown is mainly caused by the failure of mechanical sealsFailure of the performance is mostly leakage, the reasons for the leakage are the following:(1) dynamic static ring sealing surface leakage, the main reasons are: end surface flatness, roughness did not meet the requirements, or surface scratches;(2) compensation ring seal leakage, the main reasons are: the deformation of the cap, the pretension force is not uniform;the actual use of the effect shows that the sealing element failure more parts are moving, static ring end surface, centrifugal pump machine sealing, static ring end surface cracking is a common failure phenomenon, the main reasons are:(1) installation of the sealing surface gap is too large, flushing liquid can not take away the heat generated by friction;(2) liquid medium vaporized and expanded, so that the two ends of the surface by vaporized expansion force separated, when the two sealing surfaces are firmly bonded, destroy the lubrication film, thus causing the surface surface to overheat(3) liquid media lubricity is poor, coupled with the operating pressure overload, two sealing surface tracking rotation out of syncFor example, the high speed pump speed is 20445r/min, the sealing surface center diameter is 7cm, the pump is running its line speed of up to 75 m/s, when there is a sealing surface lag can not track rotation, instantaneous high temperature caused damage to the seal ingle(4) seal flushing liquid plate or filter blockage, resulting in insufficient water, so that the machine seal failurein addition, sealsurface surface slip, end surface fit when the gap caused the sealing element to fail, the main reasons are:(1) liquid medium is not clean, there are small and hard particles, at a high speed slide the seal surface, the end surface scratched and failed(2) machine pump transmission parts coaxial difference, after the pump is turned on every turn the end surface is shaken and friction once, the dynamic ring running track is different heart, resulting in the end surface vaporization, overheating wear(3) the frequent occurrence of hydraulic characteristics of liquid media causes the pump group to vibrate, causing the sealing surface to be misplaced and failedliquid media on the sealing element corrosion, stress concentration, soft and hard material syllation, erosion, auxiliary seal 0 ring, V-ring, concave ring and liquid medium is incompatible, deformation will cause mechanical seal surface damage failure, so its damage form to be comprehensive analysis, find out the root cause, to ensure long-term operation of mechanical seal