Vulnerable parts of centrifugal pumps

Vulnerable parts are the most delicate components of a water pump and require special care during use, maintenance, and servicing. So, what are the vulnerable parts of a pump, and what should be noted?

Pump Casing

The pump casing is typically made of cast iron, with some specialized pumps featuring inner lining materials. It is prone to cracking due to mechanical or thermal stress. Cracking can also occur from cavitation impacts during operation or from frozen water inside the casing in winter if not drained. If the damage is severe and cannot be repaired, the casing should be replaced.

Pump Shaft

The pump shaft is generally made of carbon steel. However, it is susceptible to damage due to manufacturing quality, usage, or installation issues. Common problems include cracks, bending, wear on the shaft neck, or damaged threads, and in severe cases, shaft breakage. If the damage is too severe to repair, the shaft should be replaced.

Impeller

The impeller is a critical working part of the pump, usually made of cast iron. It is prone to damage due to manufacturing quality or operational factors. Issues may include cracks, surface pitting or perforation from cavitation, thinning or uneven wear of blades from long-term erosion, or even breakage from debris impact. Some defects can be repaired, while others may require replacing the impeller entirely.

Bearings

Sliding Bearings: The bushings of sliding bearings are typically made of copper-tin alloy, which has poor wear resistance. They are among the most prone to wear and burning. Bushings can usually be repaired or replaced.

Rolling Bearings: Rolling bearings generally have an average lifespan of 5,000 hours. However, improper installation, prolonged use, or poor maintenance can lead to wear or damage. While some individual components of rolling bearings can be replaced, the entire bearing often needs to be replaced as a whole.

Wear Rings

Also known as leakage reduction or wear rings, these are among the most easily worn parts of a pump. They can be repaired or replaced when worn. When installing new wear rings, their inner diameter should match the outer diameter of the impeller inlet. If the impeller inlet outer diameter is worn, it can be machined to remove grooves or ellipticity, after which a wear ring with a smaller inner diameter should be installed. The impeller inlet outer diameter can generally be machined up to three times.

Packing

Packing tends to harden and lose elasticity over time, leading to air or water leakage in the pump. It is generally recommended to replace old packing with new material.

Oil Seals

Oil seals are rubber components prone to wear and aging. They should generally be replaced with new ones when necessary.