GIW has tips on how to extend the life of a slurry pump shaft.
GEORGIA – While GIW Industries’ pumps help users succeed every day, some materials can break down over time – either from misuse or from contact with abrasive or corrosive materials.
Shaft sleeves are cylindrical metal tubes designed to protect pump shafts from erosion, corrosion, and wear at critical points, such as at the stuffing box. The shaft sleeve is a wear component, like brake pads on a car, and is designed to be more time and cost efficient to replace than the shaft itself (like the entire braking system).
One GIW customer discovered during an inspection that dirty seal water had cut the shaft sleeve in half, causing a leak. As a temporary measure, the millwright tightened the sleeve and moved it inward. However, this caused a secondary wear pattern and did not stop the leak. A second tightening prevented the sleeve from rotating and caused a horizontal wear pattern in one location. By this point, the customer should have realized that the sleeve was beyond repair. If wear patterns have already formed on the shaft sleeve, moving it will only worsen the wear and cause new wear patterns to form in the area relative to its original cause.
To better understand this, think of slurry and contaminated sealing water like liquid sand paper. Both can be highly corrosive and abrasive. Moving the shaft sleeve will only relocate the groove and initiate the generation of another one. Tightening the gland compresses the packing and reduces the cooling effect of the sealing water; over-tightening it will make matters worse and can lead to component failure.
To prevent failure from occurring, users can take a few steps to diagnose and solve problems with the shaft sleeve before it wears out. Make this diagnosis a part of routine pump maintenance in order to avoid early sleeve replacement.
The first step is to inspect the sealing water system for adequate flow, pressure, and quality. GIW recommends clean sealing water at a sustained pressure of 10 psi above the discharge pressure of the pump. The higher pressure sealing water will prevent the pumped medium from weeping back into the stuffing box, thereby mitigating shaft sleeve wear. If the flow and pressure are within specifications, check the sealing water for corrosive properties and/or abrasive particulates. The shaft sealing system must be designed and applied according to the parameters for the pump.
If a user inspects the system and found that the shaft sleeve is worn beyond repair or leaking, it may be time to replace it. Fortunately, shaft sleeves are designed to be more time and cost efficient to replace than the entire shaft, making replacement a “no brainer” as far as cost and repair time are concerned. Shaft sleeves are available in different materials to combat all combinations of wear and corrosion.
Find the shaft sleeve in any of multiple material to suit every application at www.KSB.com/ksb-us/Products_and_Markets/Mining/.