What are the causes of slurry leakage from the packing of the slurry pump?

Discover the key reasons for slurry leakage from packing in slurry pumps. Our article explores common causes, including improper packing installation, wear and tear, and incorrect pressure settings. Learn how to identify and prevent leaks to enhance pump performance and prolong equipment lifespan.

 

In industrial production, slurry pumps play a critical role in conveying slurry containing solid particles, serving as indispensable equipment in industries such as mining, metallurgy, and power. However, slurry leakage from the packing during operation is a common and troublesome issue. It not only causes medium waste and work environment pollution but can also affect equipment normal operation and even trigger safety accidents in severe cases. Exploring the causes of slurry leakage from slurry pump packing can be primarily analyzed from aspects such as installation and maintenance of the slurry pump, characteristics of the packing itself, properties of the conveyed medium, and the pump's operating conditions.

 

1. Factors Related to the Packing Itself: Hidden Risks from Wear and Defects.

The slurry conveyed by slurry pumps contains solid particles, which act like countless tiny "abrasives." As the slurry pump operates, the slurry carrying these particles continuously erodes the packing. Over time, this prolonged abrasion causes the material on the packing's surface to gradually detach, damaging its originally tight structure. Just as a smooth stone becomes rough and pitted after prolonged water erosion, the sealing performance of the packing deteriorates. As the wear intensifies, gaps form in the originally effective sealing barrier, allowing slurry to seep through and eventually leading to leakage.

 

Prolonged use of the packing exposes it to environmental factors such as temperature and pressure, leading to aging. For example, rubber-based packing loses its original elasticity in high-temperature environments over time, becoming stiff and brittle. This is akin to an aged rubber band that can no longer tightly wrap around an object and loses its elasticity, failing to effectively fill the gap between the shaft and the pump casing. When the gap cannot be fully sealed, slurry leaks through, causing leakage issues.

 

The quality of the packing is crucial to its service life and sealing performance. If the packing is flawed in material selection—such as lacking wear resistance or corrosion resistance—it cannot withstand the abrasion from particles or corrosion from the medium in the slurry pump. Additionally, manufacturing defects such as air holes or cracks in the packing can expand during use, making it more prone to damage. Once the packing is damaged, its sealing function fails, leading to slurry leakage.

 

2. Installation and Maintenance Factors: Risks Caused by Improper Operation.

During packing installation, the precision of the packing gland is critical. If the packing gland is installed unevenly, the packing will experience unequal pressure. Imagine closing a box lid crookedly—the contents inside cannot be tightly secured. Similarly, under uneven pressure, part of the packing undergoes significantly faster wear due to higher friction and impact. As local wear intensifies, the sealing performance is compromised, inevitably causing slurry leakage. Moreover, the amount of packing installed must be accurately controlled. Insufficient packing fails to form an effective sealing layer between the shaft and the pump casing, allowing slurry to easily leak through; excessive packing increases friction between the packing and the shaft, generating substantial heat during operation and accelerating wear, which ultimately leads to leakage.

 

The normal operation of slurry pumps relies on regular inspection and maintenance, especially for the packing as a key sealing component. If operators do not promptly monitor the wear of the packing and fail to replace it when it is excessively worn, its sealing performance will no longer be adequate, leading to leakage. Additionally, the packing requires proper lubrication and periodic adjustment during operation. Lack of regular lubrication increases friction between the packing and the shaft, accelerating wear; failure to adjust the packing tightness regularly reduces sealing effectiveness. Prolonged neglect of maintenance causes continuous deterioration of the packing's performance, eventually leading to leakage.

 

3. Slurry Pump Operating Conditions: Impacts from Abnormal Operation.

Shaft oscillation during pump operation severely damages the packing's sealing performance. When the shaft oscillates, the sealing surface between the packing and the shaft becomes unstable, subject to continuous impact and friction. This is similar to applying a shaking force between two closely fitting objects, causing their tightness to rapidly decline. Shaft oscillation can stem from various causes: bearing damage destabilizes the shaft's support, leading to oscillation; a bent pump shaft alters its normal trajectory, causing oscillation; improper coupling installation results in uneven force on the shaft during rotation, inducing oscillation. Regardless of the cause, shaft oscillation accelerates packing wear, damages sealing performance, and triggers slurry leakage.

 

Pressure fluctuations in the conveying system during slurry pump operation also affect the packing. When the system experiences significant pressure fluctuations, especially sudden increases, the pressure on the packing surges. If the pressure exceeds the packing's sealing limit, it can no longer contain the slurry, which then breaches the seal and leaks from the packing. This is analogous to a dam breaching under the immense pressure of floodwater—slurry gushes out from the packing like floodwater, causing leakage.

 

4. Medium Characteristics: Damage Caused by Special Properties

When a slurry pump conveys corrosive slurry, the packing acts as a defensive barrier exposed to a "corrosive army." Corrosive media continuously erode the packing, gradually deteriorating its material and structure. As corrosion progresses, the packing's sealing performance diminishes until it can no longer prevent slurry leakage. This is similar to metal corroding in acid, losing its strength and function—the packing likewise loses its sealing capability under corrosive media.

 

High-temperature media also negatively impact the packing. When the slurry temperature is too high, the packing's material properties change: high temperatures reduce its elasticity, making the originally soft and compliant packing stiff and unable to tightly conform to the shaft. Additionally, high temperatures increase the packing's hardness, further affecting its fit with the shaft. Reduced sealing effectiveness allows slurry to leak through the gaps between the packing and the shaft. Just as high temperatures soften and deform wax, altering its shape and properties, high-temperature media change the packing's characteristics and undermine its sealing performance.

 

Conclusion

Slurry leakage from slurry pump packing is the result of multiple factors. Whether due to wear and quality issues with the packing itself, improper installation and maintenance, abnormal slurry pump operation, or special medium characteristics, any of these can trigger leakage. Understanding these causes helps in implementing targeted preventive and corrective measures in practical production, ensuring stable operation of slurry pumps and minimizing losses and disruptions caused by leakage.