Why Mechanical Seals fail in a Pump ?

Mechanical seals are a vital component in the design of pumps and are widely used to prevent leaks at the interface between the rotating shaft and stationary housing. Despite the advances in materials and designs, mechanical seals still fail in pumps. The failure of mechanical seals in pumps can be caused by a range of factors, including design, material choice, installation, operation, and maintenance. In this article, we will discuss some of the most common reasons for mechanical seal failure in a pump. 

1. Improper installation One of the most common causes of mechanical seal failure in a pump is improper installation. An improperly installed mechanical seal can lead to misalignment of the seal faces, uneven loading, or incorrect torque. Any of these issues can cause premature wear and tear, resulting in seal failure. In some cases, the seal faces may not mate properly, resulting in a leak. 
2. Incorrect material selection The choice of materials for the mechanical seal is another important factor that can cause seal failure. The selection of the wrong material can lead to chemical or thermal degradation, which can cause the seal to fail. In addition, materials that are too soft or too brittle may be prone to excessive wear and tear or cracking, respectively, leading to seal failure. 
3. Thermal cycling Thermal cycling is another factor that can contribute to the failure of mechanical seals in pumps. Pumps that experience rapid temperature changes can cause the seal faces to expand or contract at different rates, resulting in deformation or misalignment. In addition, thermal cycling can cause the elastomers used in the seal to degrade, leading to leakage or failure. 
4. Corrosion: Corrosion is a common cause of mechanical seal failure in pumps that handle corrosive fluids. Corrosion can lead to pitting, which can cause the seal faces to wear prematurely. Additionally, corrosion can cause the elastomers used in the seal to degrade, leading to seal failure. 
5. Abrasion and erosion Abrasion and erosion can cause mechanical seals to fail, particularly in pumps that handle abrasive fluids. Abrasion can wear down the seal faces, leading to a leak, while erosion can cause the seal to crack or deform. The choice of the right seal material and design can help minimize the impact of abrasion and erosion. 
6. Excessive vibration Excessive vibration can cause mechanical seals to fail prematurely. Vibrations can lead to misalignment of the seal faces, which can cause wear and tear. Additionally, vibrations can cause the seal faces to separate, resulting in leakage. 
7. Improper maintenance Improper maintenance is another factor that can contribute to mechanical seal failure in pumps. Inadequate lubrication, incorrect alignment, or incorrect torque can all cause premature seal failure. In addition, failing to inspect or replace the seal when required can lead to leakage or failure. 
8. Cavitation: Cavitation is the formation of vapor bubbles in a liquid that collapse when the pressure is reduced, causing shock waves that can damage the pump and seals. Cavitation can cause the seal faces to wear down and the elastomers to degrade, leading to seal failure. 

In conclusion, mechanical seal failure is a common issue in pumps and can have a range of causes, including improper installation, incorrect material selection, thermal cycling, corrosion, abrasion and erosion, excessive vibration, improper maintenance, and cavitation. To prevent mechanical seal failure in pumps, it is important to choose the right material and design for the seal, install it correctly, perform regular maintenance, and operate the pump within its recommended parameters.