Seals are critical components in various mechanical and industrial systems, ensuring machinery's proper functioning and efficiency by preventing leakage, containing pressure, or excluding contaminants.
Understanding common seal failures and their prevention is essential for maintaining the longevity and reliability of these systems.
For over 60 years, Rocket Seals has been serving OEM and MRO customers worldwide. As leaders in our industry, we know the best solutions for any application, and how to optimize your equipment and ensure you get the most out of it.
To better understand how to maintain your seals and applications, we’ll explore several types of seal failures, focusing on mechanical seals and hydraulic seals, and offer insights into their causes and prevention.
Understanding Seal Failure
Seal failure can lead to system downtime, increased maintenance costs, and even catastrophic equipment failures. It's crucial to recognize the symptoms and causes of seal failure to implement effective preventative measures.
Mechanical Seal Failure
Mechanical seals are used in pumping systems to seal the interface between the rotating shaft and the stationary pump casing. These seals are prone to failure for various reasons:
Mechanical Seal Leakage Causes
- Improper Installation: Incorrect installation can lead to misalignment between the seal and the shaft, causing premature wear and leakage.
- Inadequate Material Selection: Using materials that are not compatible with the fluid being pumped or the operating conditions (temperature, pressure, etc.) can degrade the seal.
- Wear and Tear: Over time, even well-maintained seals will wear out. Regular inspection and maintenance are required to ensure they are replaced before failure occurs.
Prevention Tips
- Ensure proper training for personnel on the correct installation techniques of mechanical seals.
- Select seal materials that match the specific chemical, thermal, and pressure conditions of the application.
- Schedule regular maintenance checks to assess the wear and operational viability of mechanical seals.
Pump Seal Failure
Pump seals are critical in preventing fluid leaks in pump systems. The failure of these seals can be catastrophic, leading to significant downtime and repair costs.
Common Causes of Pump Seal Failure
- Cavitation: This occurs when vapor bubbles form in the liquid being pumped, causing violent collapse near the seal faces and leading to damage.
- Chemical Attack: Exposure to aggressive chemicals can degrade seal materials, leading to failure.
- Thermal Deterioration: Excessive temperatures can cause seal materials to deform or lose their elastic properties.
Prevention Tips
- Monitor and control pump operating conditions to avoid cavitation.
- Use seals made from materials specifically designed to resist the chemicals being handled.
- Ensure the cooling systems are adequate to maintain a safe operating temperature.
Hydraulic Seal Failure
Hydraulic seals are vital for the operation of hydraulic systems, which operate under high pressure. The integrity of these seals is crucial to maintaining system performance and preventing leaks.
Types of Hydraulic Seals
- Piston Seals: These seals prevent fluid from flowing across the piston as it moves within a cylinder.
- Rod Seals: These seals prevent leakage along the rod in hydraulic cylinders.
Causes of Failure
- Pressure Fluctuations: Sudden or extreme changes in hydraulic pressure can cause extrusion and eventual rupture of the seal.
- Side Loading: Misalignment of the cylinder components can put uneven pressure on seals, leading to premature wear and failure.
Prevention Tips
- Regularly check and maintain hydraulic fluid levels and quality to ensure proper lubrication and pressure balance.
- Align hydraulic system components properly during installation and after any maintenance.
Environmental and Operational Impact on Seal Performance
Understanding the influence of environmental and operational factors on seal performance is crucial for optimizing seal longevity and effectiveness.
Factors such as temperature extremes, contamination, vibration, and the operational cycles of the equipment can dramatically affect seal integrity.
Impact of Contaminants
- Particulate Contamination: Dirt, dust, and other particulates can enter the sealing interface, causing abrasion and premature wear of seal faces.
- Chemical Contamination: Unplanned chemical exposure can degrade seal materials, leading to loss of elasticity and seal failure.
Temperature Extremes
- High Temperatures: Can cause thermal expansion of seal components, potentially leading to deformation and loss of sealing capability.
- Low Temperatures: May reduce the flexibility of seal materials, increasing the risk of cracking and leakage.
Vibrational Forces
- Equipment Vibration: Continuous vibration can lead to dynamic loads that fluctuate, stressing the seal and potentially leading to failure.
- Operational Misalignment: Vibration can also stem from misaligned rotating parts, which increases stress on the seals and accelerates wear.
Cyclic Stress
- Frequent Starts and Stops: Equipment that starts and stops frequently imposes intermittent pressures and temperatures on seals, which can fatigue materials over time.
- Pressure Surges: Sudden changes in pressure, especially in hydraulic systems, can exceed the design limits of seals, leading to blowouts or extrusions.
Prevention Tips
- Implement rigorous contamination control measures to maintain clean operating environments.
- Choose seals with materials specifically rated for the expected temperature and pressure ranges.
- Ensure proper alignment and balance of mechanical components to minimize vibrations.
- Design operational protocols that mitigate the effects of cyclic stresses, such as gradual ramp-up and ramp-down procedures.
Seal Materials and Design Considerations
Choosing the right materials and design for seals can significantly reduce the risk of failure.
Seal Face and O-Ring Considerations
- Seal Face Material: The choice of material for the seal face affects its wear resistance and suitability for different fluids and temperatures.
- O-Rings and Metric O-Rings: These are used to create tight seals at various interface points. Metric O-rings are sized to standard dimensions, which must be accurately matched to their housings.
Material Properties
- Chemical Compatibility: The seal material must be able to resist the chemicals it will be exposed to.
- Temperature Resistance: The material must withstand the minimum and maximum temperatures it will encounter.
- Pressure Suitability: The material needs to be capable of handling the system’s pressure without deforming.
We're Here to Protect Your Seals
Understanding common seal failures and their prevention is crucial for the reliability and efficiency of mechanical and hydraulic systems. By focusing on proper installation, material selection, and regular maintenance, many of these failures can be prevented, ensuring that systems operate smoothly and last longer.
Whether dealing with pump seal failures or the intricacies of hydraulic seals, a proactive approach to maintenance and design can save both time and money while reducing the risk of downtime.
Get in touch with a member of our team if you have further questions about how to protect your seals, and to discuss how we can optimize your application today.