Hydraulic systems can contain many different fluids that can have drastically different properties. Depending on the machine or equipment, the seal may be containing grease, transporting caustic fuel, or pressurizing water. There are many different elements a seal may be exposed to while machines operate. OEMs need the seals in their systems to last long, contain systems, and prevent friction. By understanding why seals degrade when exposed to aggressive fluids, OEMs can help prevent the material in the seals from failure. This guide will help you identify seal swell and understand the underlying causes. Preventing seal failures can help an OEM reduce Maitenence costs and improve equipment reliability.
Why Seal Swell is a Major Issue for OEMs
The Hidden Cost of Seal Swell – The major concern for any seal is leaks. If a seal swells, it will contort and allow liquid to escape from it where it normally would not. The softened seal can also increase friction from the extra pressure. If the wrong polymer absorbs liquid and the seal is swelling, the cost could rack up quickly replacing the seal repeatedly.
Industries Most Affected by Seal Swell – Some industries struggle with fluid compatibility as they deal with transporting liquid. Oil and gas, chemical processing, food and beverage, and hydraulic systems all move large amounts of liquid. The more a seal encounters a liquid, the more likely it will be to absorb and swell.
The cause of seal swell is straightforward, but understanding the polymer limitations, identifying the problem, and setting up a maintenance system to identify problem areas.
What Causes Seals to Swell and Degrade?
Fluid Absorption and Polymer Breakdown
Certain oils, fuels, and solvents can diffuse into rubber seals. The expansion of the seal causes a myriad of problems including leaks, friction, and depressurization. Polymers can be designed and built to resist this swell, but the seal needs to be calculated before being used in the machines. Work with a seal manufacturer to determine the best matchup for whichever fluids you have in your systems.
You’ll notice a seal might gain a gummy texture, expand in size, or lose its elasticity completely. There may be some discoloration depending on the fluids diffusing into the seal, but normally oil, gas, and solvents do not cause a major discoloration.
Chemical Reactions and Incompatibility
Your systems may contain acids, oils, and fuels. Thos chemicals are harsh on any polymer, but some elastomers are developed to withstand that degradation for longer. Traditional rubber seals will break down when exposed to such caustic elements.
This acidic breakdown can look like cracking, hardening, or pitting in the surface of the seal. The caustic fluids are breaking apart the seals and they begin to flay and lose their elastic nature.
High-Temperature Fluid Exposure
Why does heat accelerate seal swell? When rubber is heated it expands, likewise when it is cooled it compresses. If a seal is experiencing high temperatures for too long, fluctuating from high to low temperatures, or is kept in low temperatures the seal may lose it’s efficacy. Heat specifically causes the pores in any rubber to expand open with the heat. These expanded pores allow more of the caustic chemicals to seep into the seal.
When you start to notice blistering on the seal, severe warping, or the seal is becoming brittle and snaps easily it could mean the seal is coming into contact with acidic compounds and experience too high of a temperature all at once. Make sure to check for small blisters at the lip of the seal, and to test the seals regularly to see if certain joints or systems in the machine are experiencing high-temperature problems.
Additives and Lubricants in Hydraulic Systems
We mentioned gases and oils degrading seals. It’s important to note that many lubricants are petroleum based. These lubricants will eat away at the seal even if it is working with compatible fluids. Some additives in lubricants also degrade seals much faster than regular use. It’s important to review what lubricants are being used with which seal. You will want to look for discoloration, residue buildup, or softening of the polymer. These can lead to leaks, seals ripping apart, or metal-on-metal contact is a seal softens too much. The most impactful step you can take in preventing material degradation with aggressive fluids is to schedule a routine maintenance system to double check seals throughout the month.
Best Practices for Preventing Seal Swell and Material Breakdown
When installing a new seal in your equipment it’s always important to match the seal polymer and fluid compatibility. You can always double check, absolutely free, with the System Seals Fluid Compatibility form. This should give you a good idea of what polymers can handle what fluids. Certain seal compositions resist certain acidic fluids better than others, so it’s always a good idea to double check before installation.
The second most important thing an OEM can do to prevent seal failure due to seal swell is to create a monitoring and checking system. It could be beneficial to schedule a routine check for seal swell in your machines every few weeks to once a month, depending on how aggressively the machine is operating. If your equipment is running most of the time you may want to check it even more than that. Catching seal swell before the seal fails is a great way to ensure your machine runs longer with fewer problems.
Lastly, check with your seal manufacturer and ask about barrier coatings for the seals in your equipment. These types of coatings can help target which acidic compound may seep into the seal and help prevent that diffusion. Think of it like sealing your seals. Also ask them about advanced formulations as many seal manufacturers spend a lot of time and money researching and developing advanced sealing solutions for niche scenarios.
How OEMs Can Reduce Downtime and Maintenance Costs
We’ve mentioned it before, but it cannot be reiterated enough: Checking your seals is the best way to prevent seals failing from seal swell. Creating a routine maintenance schedule is a bit of work, but the return on investment jumps through the roof if it helps prevent the catastrophic failure of an important piece of equipment.
Partnering with a reputable seal manufacturer will also open a lot of doors for your company. And OEM that builds a good relationship with a seal manufacturer will have access to cutting edge designs, advanced polymers and elastomers, and personalized service. Many Seal manufacturers will develop guides on installing seals or even come to your facility and install the seal properly themselves.
Investing into modern-day advanced sealing solutions will also save you money in the long run. The up-front cost of a state-of-the-art seal will inevitably be more, but the lifespan of some advanced sealing solutions can be nothing short of incredible. A seal like that could cost three times as much, but last five times longer than normal.
Conclusion: The Key to Reliable Sealing in Aggressive Environments
Using the wrong material in a seal can cause catastrophic failures in your machines, and it wastes production time that OEMs do not have. Having a major shutdown on a key piece of equipment can set you back for the entire production timeline. Seal Swell is notorious for sneaking up on operators, and a seal may not show signs until it is close to failing.
Make sure to invest in higher-quality seals for high problem areas. If you notice a specific machine, or segment of a machine, is burning through seals too quick or has failed multiple times, take the extra time and invest in higher quality seals from a reputable manufacturer and help avoid those sudden pauses in production.
Hopefully this guide has prompted you to begin routinely checking your seals in your cornerstone equipment and set up guardrails for maintenance practices. If you ever have any questions about identifying seal swell, installing seals correctly, or checking fluid compatibility, make sure to reach out to us here at System Seals.
