Failure Analysis of Mechanical Seal for Centrifugal Pump
Centrifugal pump shutdown is mainly caused by the failure of mechanical seals formed. The failure of the performance are mostly leaked, leaked by the following reasons:
① dynamic ring sealing surface leakage, the main reasons are: end flatness, roughness does not reach the demand, or the appearance of scratches; end surface between the particulate matter, the formation of both ends can not be the same work; device is not in place, the method is not correct.
② compensation ring ring leakage, the main reasons are: gland deformation, preload force is not uniform; device is not correct; ring quality does not meet specifications; ring selection is wrong.
The actual use of the role of the seal component failure is the most part of the dynamic and static end of the ring, centrifugal pump seal dynamic, static ring face is a common failure of the surface representation of the main reasons:
① device sealing surface gap is too large, flushing fluid too late to take the heat of the deputy deputy of the conflict; flushing fluid leakage from the sealing surface gap, the formation of end surface overheating and damage.
② vaporization of liquid medium swells, so that both sides of the face by the vaporization of expansion and strong separation, when the two sealing surface of the force fit, the damage to the smooth surface and then form the surface appearance of overheating.
③ liquid medium, poor smoothness, coupled with operating pressure overload, the two sealing surface stare change is not synchronized. For example, high-speed pump speed is 20445r / min, the sealing surface of the middle diameter of 7cm, the line speed of the pump work up to 75m / s, when there is a sealing surface lag can not stalk rotation, instantaneous high temperature sealing surface damage.
④ seal flushing fluid orifice plate or filter blockage, the formation of water shortage, the mechanical seal failure.
In addition, the surface of the sliding surface of the sealing surface, the end surface of the gap when the gap caused by sealing element failure, the main reasons are:
① liquid medium is not clean, there are small particles of hard quality, high speed slide people sealing surface, the end surface scratches and failure.
② pump drive coaxial poor, the pump is open after the end of each revolution is shaking a collision, the work of the orbit is not concentric, forming end surface vaporization, overheating wear.
③ frequent hydraulic characteristics of the liquid medium led to oscillation pump group, the formation of sealing surface dislocation and failure.
Liquid medium on the sealing element corrosion, stress gathering, hard and soft data cooperation, erosion, auxiliary sealing 0-ring, V-ring, concave ring and liquid medium incompatibility, deformation and so on will form mechanical seal surface damage failure, Therefore, the way to analyze the damage to find out the root cause, to ensure long-term mechanical seal work.
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