How Do I Know How Much Gasket Compression is Too Much?

If you’ve never given much thought to gasket compression (gasket what?), you likely have the mindset of “clamp ‘er in there the best you can”. While this mantra may work for you in certain scenarios, it is definitely not ideal. Achieving the proper gasket compression via the torque placed on the bolts is actually a well-engineered, tested and verified process done with a specific type of gasket material.

However, as we all know, things never stay the same. Sometimes the torque values aren’t followed like they should be, or sometimes a material gets replaced, and flange surfaces change throughout the repetitive heat cycles. When this happens, you have to trust the performance of your gasket material. In some cases, over-compression can happen, and that can lead to problems. What are some of the warning signs of a gasket that is or has ever been compressed beyond what is recommended?

Too Much Compression

1. Material splits or tears

Hopefully seeing this symptom will be a cause for concern for you even if you don’t understand the reason why it is happening. Before reading this blog, you may have always chalked it up to a bad gasket or bad gasket material. You may need to take a closer look at how much compression you are putting on your gasket, especially if it seems to be happening regularly.

2. Leakage

Leaking gaskets are never a good thing. If this seems to happen more times than not, too much compression may be the culprit. Check that before scrapping your gaskets and trying something new.

3. Does not recover to it’s original configuration

A used gasket rarely looks as perfect as a new one, but it still should be recognizable. Permanent distortion suggests that a better quality product should be used to survive the conditions. To understand more about what should be expected with compression and recovery, check out our blog What is Compressibility & Recovery, and Why Do I Care?

How To Avoid This Issue

As you can see, gasket torque values and the actual compression of your gasket will have an effect on the performance of your application. If you are unable to verify the recommended torque values for the joint, talk to your trusted gasket material supplier. They should be able to (at a minimum) provide you with recommended flange loading and compression for a specific material and guidance in selecting a proper material for your application.

You may also find that you can no longer achieve a seal with the recommended torque values and your current gasket material. If compressibility is an issue, you may need to make a change in your gasket material. Again, your trusted gasket material supplier can guide you through this process.

How often can you trace back gasket issues to compressibility issues?Hi-Tex Product Comparison

The Great Gasket Debate: To Reuse or Not To Reuse

To reuse or not to reuse gasket material…that is the question. Depending on who you ask, you will almost always get differing answers and advice. Those people that are cost conscious will almost always recommend to reuse every gasket you can. (“There’s still more life in it!”) Those that are strictly focused on performance will always tell you to never reuse a gasket. (“Once you break the seal, you will never achieve the same level of performance!”)

As a trusted gasket material supplier, our recommendation is that you never reuse a gasket. (Ok, ok, we know you are probably thinking “of course they would say that…they just want to sell more material” – but hang with us on this one.) As an expert resource that knows gasket material inside and out, we’re going to break down some of the arguments for and against reusing, and what you need to consider when making that decision for your application. And maybe…there is a time or two that it really might be ok to reuse one.

Reusing a Gasket

If you’ve never been told, you’ve likely always wondered if that gasket could be reused. “It still looks ok, I wasn’t having any problems with it…I wonder if I could throw it back on there??” Here are some of the common arguments for reusing a gasket, and some situations where it might work to reuse.

  1. If the gasket hasn’t seen heat exposure yet of an operating unit, it might be ok to reuse.
  2. If the gasket hasn’t seen fluid exposure and swelling of an operating unit, it might be ok to reuse.
  3. “It looks ok” is more of a subjective approach, but might indicate that the gasket is still ok to use as long as the initial thickness is still correct and it has sufficient compressibility left in it to achieve a seal.

Replacing a Gasket

There are many people out there that would never replace a gasket. How does one really know if it is going to work the same way twice? Here are some of the common arguments for never reusing a gasket.

  1. Heat exposure: Exposure to elevated temperatures causes materials to deteriorate. Sometimes this means: dry out, stiffen up, saturate, get brittle, take a set, etc. Once this seal has “seated” in the application, it should not be disturbed. A new gasket is required to go through the initial seating phase and achieve a proper seal.
  2. Fluid saturation: Exposure to fluids sometimes causes materials to swell, impregnate, or saturate. In a seal situation, this often helps to create the seal. Reusing a gasket is not advised as the saturation and absorbancy condition can vary. A gasket should be assembled, then exposed to heat and fluid. A used gasket already having swelling due to the fluids should not be reused.
  3. Compression set: The third reason not to reuse a gasket is related to the first two. Once a gasket has taken a set (due to temperature and fluids), it should not be disturbed or reused. It would not have the same properties available to go through the initial compression provided by the joint and achieve the initial seal.

Our Recommendation

Like we’ve mentioned, our official position is to never reuse a gasket. As a gasket material manufacturer, we run our tests and certify our products when our material is at 100%. We know for a fact that our material can handle the conditions it is specified for IF the gasket (and joint) is designed properly, and installed correctly. What we don’t know is how our material will work after the seal has been disturbed or disassembled. It may work just fine, it may have been damaged in the process – we don’t know, and it would be impossible to test in enough conditions to enable us to come to a strong conclusion that we would have any confidence in.

We take pride in the quality and the performance of our material (as do many others), and we don’t believe the risk of damage to your application is worth the reward of saving a few dollars from reusing a gasket.

Replace to be safe!

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