Managing Submersible Pump Wear: Common Causes and Solutions

Wear is one of the main factors that limits pump life and efficiency. This article explains the key types of wear, how they affect pumps, and the practical steps that can reduce damage and extend service life. For more detailed guidance, visit the Grindex Pump School 

Understanding Wear

Wear is the gradual loss of material from a surface, and in pumps it is one of the main challenges that affects performance and lifespan. In most situations more than one wear mechanism takes place at the same time, although one is usually more dominant. The process generally follows three phases:

Phase 1: The material surface deteriorates

Phase 2: Then particles are removed through the wearing mechanism,

Phase 3: these particles are either transported away by the fluid or remain trapped between surfaces.

Erosive Wear

Erosive wear occurs when solid particles or liquid droplets strike a surface repeatedly until material is lost. On brittle materials this results in fractures, while on ductile materials it takes the form of chip formation, fatigue and shear failure. In pumping applications slurry erosion is a common example, as water carries abrasive particles that impact the components. Another form is cavitation erosion, which occurs when low pressure in a liquid forms vapour bubbles. When these bubbles collapse near a surface they create powerful jets that damage the material over time.

Image: Erosive wear on a pump propeller 

Abrasive Wear

Abrasive wear takes place when hard particles or sharp edges cut into a surface. The loss of material can happen through chip formation, brittle fracture or fatigue. In two-body abrasion the damage comes from a sharp edge on one surface scratching the other, while in three-body abrasion the wear is caused by a particle trapped between two surfaces. Abrasive materials can be sand, hardened chips from deformed metals, or oxidised particles.

Image: Diagram showing two-body abrasion and three-body abrasion

Sliding and Rolling Wear

Sliding and rolling wear develops between two surfaces that move against each other. The most common causes are shear and fatigue, often made worse by oxidation or mechanical breakdown. Adhesive wear is a good example, where tips of two sliding surfaces weld together and then tear apart. Fatigue wear is another, where fragments break away after repeated rolling contact, such as in roller bearings.

* Diagram showing Adhesive wear 

Wear in Pumps

In pumps, parts such as impellers and suction covers, which are directly exposed to the liquid, are most at risk from erosive wear. To resist this, they are often made from chromium-alloyed hardened cast iron or softer but durable materials such as nitrile rubber. In some Cases, erosive corrosion, which combines erosion and corrosion, can damage cast iron pumps in a short period of time, so harder or more corrosion-resistant materials are required. Face seals, which rotate against each other, are subject to abrasive wear and generate high temperatures. For this reason they are manufactured from heat-resistant materials such as aluminium oxide, silicon carbide or tungsten carbide.

 How to Prevent Wear

To reduce wear in pumps, focus on:

1. Using wear-resistant materials (hardened metals or rubbers)
2. Applying lubrication to prevent direct surface contact
3. Designing pumps and piping to lower water velocity and minimise particle entrapment
4. Considering patented solutions like Grindex’s suction cover

Wear can be controlled in several ways. One method is to use wear-resistant materials, for example hardened metals or rubbers. Another is to prevent surfaces from coming into direct contact, usually by applying lubrication such as oil or grease. A further method is to design pumps and piping systems to reduce the risk of wear. Larger diameter pipes can be used to lower water velocity, and pumps can be designed to minimise particle entrapment. Grindex has developed a patented suction cover that helps reduce wear in this way.

*Image showing Grindex innovation of a patented suction cover which reduces wear. 

Handling Abrasive Materials

When liquids contain high levels of abrasive material, slurry pumps with hydraulic parts made from chromium-alloyed iron or lined with rubber are recommended. Mine and construction pumps do not have a strict limit on how much abrasive material they can handle, but large particles and low flow rates generally increase erosion. Dry running should also be avoided where possible to reduce unnecessary wear.

Hardness and Wear Resistance

The hardness of the pump material compared to the abrasive particles is an important factor. As a general rule, if the particles are softer than the pump material, wear will be low, while harder particles will increase wear. For example, Grindex mining and construction pumps use impellers made from chromium-alloyed cast iron containing carbides that are harder than sand and gravel, which improves their wear resistance. For rubber components the opposite applies, as softer rubber is usually more wear-resistant than harder rubber, and the hardness of the abrasive particles makes little difference.

* A scale showing the hardness of some metals, polymers and minerals.

Work Hardening and the Mohs Scale

Some metals, such as manganese steels including Hadfield steel, have the ability to work harden. In these materials the structure is not entirely stable, and under repeated wear it transforms into a hardened state, improving wear resistance over time. To compare hardness across different materials and minerals, the Mohs scale is often used. This is a non-linear scale based on the ability of one mineral to scratch another, and provides a practical way of understanding relative wear resistance in pump applications.

Pump wear can take many forms and affects both performance and lifespan, which can increase maintenance and operational costs. It can be reduced by choosing wear-resistant materials, applying lubrication, designing systems to minimise particle impact, understanding material hardness, handling abrasive liquids carefully, and using solutions such as Grindex’s suction covers, which together help extend pump life and protect your business.

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* Content for this article was sourced from the Grindex Pump Academy.