Wear parts: impeller, volute liner and liner plates explained

A slurry pump consumes its wet end. Understanding which components wear, and in what order, turns wear-part replacement from an emergency into a scheduled maintenance task.

The impeller

The impeller does the work and takes the most punishment. As the vanes and the shrouds wear, the head developed at a given speed falls and the flow drops off. A worn impeller also changes the balance of the rotating assembly. Impellers are statically and dynamically balanced before dispatch, and should be replaced when the head at the design flow has fallen beyond what the process can absorb — not when the metal is gone.

The volute liner

The volute liner is the replaceable wear surface of the casing. It bolts in, so the pressure-containing casing is not consumed. Wear is normally heaviest at the cutwater and on the outer wall opposite the discharge, and it is uneven — which is why liners are inspected rather than replaced on a fixed calendar.

Front and rear liner plates

These are the suction-side wear plates. The gap between the impeller and the front liner has a direct effect on efficiency: as the clearance opens with wear, internal recirculation increases and both flow and head fall. Checking and re-setting this clearance is one of the cheapest efficiency measures available on a slurry pump.

Clamp band and casing joint

On gravel and single-casing pumps the clamp band holds the casing halves together. It is a structural part, not a wear part, but it is removed at every rebuild — so inspect the joint faces and the bolts while the pump is open.

Bearing assembly

The bearing cartridge carries the shaft and absorbs the radial and axial loads. Supplied complete, it can be exchanged in the workshop or in the field, which keeps a rebuild inside a normal maintenance window. Oil level and seal condition decide how long it lasts.

Planning a change-out

• Record the duty point at commissioning, so a fall in performance can be measured rather than guessed.
• Inspect the wet end at fixed intervals — initially more often than you expect to need to, until the wear rate for your slurry is known.
• Hold one impeller, one volute liner and one set of liner plates as critical spares.
• Quote wear parts against the pump model and serial number, so the material grade matches the original.

Wear parts for the slurry and gravel ranges are cast in our own foundry to the original drawing, which means the material grade and heat treatment are controlled rather than reverse-engineered from a sample.