What do you need to know about pumps and their bearings?

Understanding the different components that make up a pump allows you to implement effective and best practice maintenance procedures. 

In this blog, our team shares their knowledge about bearings and how important they are to the successful operation of your centrifugal pump. We answer the questions you care about most, so check out these answers.

 

What is a bearing?

A bearing is a mechanical assembly consisting of a rolling element, cage and inner and outer rings used in rotating shaft or linear shaft applications.

Bearings are a small part of the pumping system, but they play a vital role. The assembly carries the load of the pump and allows rotation. They must be properly lubricated and monitored for temperature to prevent bearing failure.

 

What happens to the bearings when the pump is running?

When your pump is running, the bearings are subjected to high axial loads, edge lubrication, and high operating temperatures and vibrations. All the time, these bearings are trying to minimize friction. 

 

What are the different types of bearings available?

There is a wide range of bearings suitable for centrifugal pumps, and different types are selected depending on the conditions of use or the preference of the end user. There are several different types of bearings depending on the application, including ball or roller bearings, linear bearings, and mounting versions that can use rolling element bearings or plain bearings.

Depending on the type of pump you have, there are a number of bearings that may be suitable.

1. Roller bearings use cylindrical rollers between moving parts to reduce friction and support radial and axial loads.

2. Ball bearings use balls to support the movement of the parts, and although simple in design, they are suitable for high speeds and are easy to maintain.

3. Pasteurized bearings are sleeve bearings coated with pasteurized alloy and are commonly used in motors, pumps, turbine generators and fans.

4. Sleeve bearings are suitable for high speeds. These bearings are only suitable for radial loads and are designed to float.

5. Pivot tile bearings, also known as tilting tile bearings or Kingsbury bearings, are suitable for axial loads and are installed as thrust bearings in high-power centrifugal pumps.

6. Angular contact bearings with inner and outer ring raceways, which are displaced relative to each other in the direction of the bearing axis. These bearings are designed to carry loads. 

 

How do bearings fail?

The most common cause of pump bearing failure is not actually fatigue. Thrust bearings in centrifugal pumps sometimes fail before the theoretical life specified by API or ANSI standards for the following reasons.

► Contamination: This comes from three potential sources; liquids, metal particles, and dirt or dust. Exposure to dust or dirt can be reduced if the bearings remain in their original packaging and are not exposed to the components prior to installation. Also, when handling bearings, do not contaminate them with dirty or greasy hands. 

► Inadequate or ineffective lubrication: Proper lubrication of bearings prevents direct metal-to-metal contact, reduces friction, wear, rust and corrosion, and extends service life. However, inadequate or ineffective lubrication can lead to bearing failure and increase the amount of heat and friction generated. Most lubrication failures occur due to the use of the wrong lubricant, too little or too much grease/oil, and contamination of grease/oil with objects or water. 

►Incorrect mounting or installation: During mounting and installation, the operator must avoid misalignment or shaft deflection and be aware of radial internal clearance. 

► Operating stress and bearing selection: If the load becomes high, overload and early fatigue may occur. If the load is too low, improper sliding and rolling element loading may occur. The first indication of these problems is usually abnormal noise and/or elevated temperatures. 

► Environmental effects: If the operating environment is not taken into account, lubrication and mounting failures can occur. These environmental influences may include

❋ Dust and dirt contaminating the bearing

❋ Corrosive media or water

❋ Ambient operating temperatures

❋ Current path or electrolyte corrosion

 

Want to know more about the Bearings, Pumps series? Contact SGB today! Our team is dedicated to ensuring the reliability, durability and longevity of your pumps and their components.