Best Practices: Dry Gas Seal Maintenance
Dry gas seals are critical components in rotating equipment such as compressors, providing a reliable barrier against leaks with wear. A low-friction profile is a primary advantage of the gas seal, as it results in a drastic reduction in required maintenance. Nonetheless, ensuring you get optimal performance and maximum longevity from your dry gas seal requires you to perform routine inspections and preventive maintenance as recommended by the seal manufacturer. Every situation is unique, but best practices for dry gas seal maintenance should always touch on the following:
1. Regularly Inspecting and Monitoring
Any proactive dry gas seal maintenance program should include scheduled inspections and monitoring. The manufacturer of your dry gas seal should provide guidelines for recommended frequencies of inspection and part replacement based on the particulars of your seal and system. Follow that to the letter, and you should get the longest, most productive life out of your dry gas seal.
Seal performance should be monitored through pressure, temperature, and flow readings. Early detection of performance degradation can reveal issues before they can become real problems. Your system may incorporate condition-monitoring tools, such as vibration analysis and leak detection. Use those tools to assess the health of your seal without taking it apart, or even shutting it down.
To do a thorough inspection of your dry gas seal, however, you will need to disassemble it periodically. These are the main components of your dry gas seal that need to be assessed from time to time:
Seal Faces
Though dry gas seals are subjected to far less friction than other seal types, the seal faces do experience a degree of wear through normal operations. High pressure, and contamination are the main causes of seal face wear in dry gas seals. A compromised seal face can degrade efficiency and cause leaks. Periodic inspection and part replacement can practically eliminate the chance of seal face failure.
O-Rings or Elastomeric Seals
O-rings provide a secondary seal to help prevent gas leaks. Over time, they can degrade due to exposure to harsh gases or extreme temperature fluctuations. As O-rings age, they lose elasticity, harden, and eventually begin to crack and break down. Inspection and scheduled replacement are the best ways to prevent this from happening.
Seal Support System Components (e.g., Filters)
Dry gas seals should always have filtration systems to ensure that the gas entering the seal is free of contaminants. These filters can become clogged or damaged, allowing debris into the seal area where it can accelerate wear. The filtration elements should be inspected and replaced on a regular basis, as recommended by the seal manufacturer.
Rotating and Stationary Components
Some dry gas seal designs incorporate small springs or bearings to keep the seal faces in close contact. These parts can fatigue or wear out over time, resulting in misalignment or reducing the force needed to maintain a proper seal. This can lead to seal face separation or contact failure.
Dynamic Gaskets and Bellows
Pressure changes, extreme temperature changes, and vibration can all contribute to mechanical stress on gaskets and bellows, causing them to wear and crack over time. These parts need replacing before they have a chance to degrade seal performance.
Labyrinth Seals
These secondary seals are designed to help prevent contamination from external sources. They do not rely on direct contact with moving parts, so they experience minimal wear, but they can be compromised over time by harsh environments, extreme temperature or pressure changes, or the presence of dust, dirt, or other abrasive substances. Monitoring and inspecting labyrinth seals should be part of the ongoing maintenance program.
Gas Supply System Components
These parts control the pressure and flow of the gas entering the seal. They can become blocked, damaged, or corroded, leading to poor seal performance and gas starvation. Again, optimal seal health and performance over a long working life can be assured by the regular inspection and periodic replacement of these parts.
2. Maintaining Cleanliness
Contaminants are the primary enemy of dry gas seals. Ensure that the gas entering the seal is free of dirt, dust, and moisture. Implement high-quality filtration systems to keep impurities out of the seal gas supply. Regularly inspecting and replacing filters as specified by the seal manufacturer is the best way to avoid compromises to performance.
3. Monitoring Gas Supply
The quality of the gas supply is critical. A dry, clean, and consistent gas supply ensures that the seals operate within design parameters. Moisture in the gas can lead to condensation, increasing wear and reducing the seal’s effectiveness. Monitor gas dew points and maintain systems to prevent moisture from entering the seal area.
4. Checking Alignment
Misalignment of the rotor can result in uneven wear and potential seal failure. Regularly check and adjust the alignment of rotating shafts and components. Misalignment can cause excessive vibrations, which deteriorate seal performance and lead to premature failure.
5. Controlling Operating Conditions
Ensure that the seal operates within the manufacturer’s recommended pressure and temperature limits. Operating at extremes or beyond design specifications can reduce the lifespan of the seal. Keep a close eye on both dynamic and static conditions, as pressure fluctuations or thermal shocks can stress the seal components.
6. Purging Seal Gas
Performing periodic seal gas purges helps eliminate contaminants that may have accumulated in the seal chamber. This process can extend the life of the seal by maintaining a clean environment around it. Always follow the manufacturer’s guidelines when performing seal gas purges.
7. Training Personnel
Improper handling of seals during inspections or repairs can lead to damage. Proper training of maintenance personnel is essential. Staff should be well-versed in the equipment’s operational requirements and maintenance procedures.
If All Else Fails, Ask an Expert
Again, the best thing you can do to ensure the long, productive life of your gas seal is to follow the manufacturer’s advice. As a prominent developer and manufacturer of mechanical seals for over 60 years, Stein Seal Industrial has literally written the book on dry gas seal maintenance many times over. We have provided this article as a general overview of best practices to follow for the maintenance of any dry gas seal. But the particulars of your seal, and the parameters of your operation, will determine the frequency of inspections and part replacements needed. Follow the guidelines provided by your seal manufacturer for long-term success. Alternatively, consult with an expert, like Stein Seal Industrial, to have your seal and system analyzed and determine the best approach.
