Can the sealing ring still be used if it has slightly deformed?

Many people think, "It's just a little crooked. It should be fine to put it back." However, the uniqueness of this sealing ring part lies in the fact that its entire value lies in that uniform and continuous sealing line. Once it deforms, even a slight deformation that is almost invisible to the naked eye, the integrity of this sealing line has already been compromised.

Let's first discuss what exactly the deformation of the sealing ring means.

When the sealing ring is in the installed state, it should be uniformly compressed between the grooves or mating surfaces. It relies on its own elastic rebound force to form a stable contact pressure band between the two mating surfaces, thereby blocking the passage of liquids and gases.

Once deformation occurs - even if it is only a local bulge, uneven pressure, or the cross-section is no longer a standard circle - it means that this contact pressure zone has become uneven. The deformed areas have insufficient pressure, while the non-deformed areas have excessive pressure. This unevenness is not to the "barely usable" level, but rather to the "already leaking" or "about to leak" level.

What specific practical problems will this bring about?

First, the seal has failed, and it is a gradual process.

There will be microscopic gaps between the deformed area and the mating surface. At rest, leakage may not be immediately noticeable. However, once the equipment starts operating, factors such as pressure fluctuations, temperature changes, and vibrations are superimposed, and the medium will begin to seep from the weakest point. Initially, it might only be oil seepage or gas dripping. Users may think "it can hold on for a while", but in reality, the leakage will increase over time until it becomes completely out of control. Many major failures of equipment occur because a "minor leakage was not taken seriously".

Second, it accelerates wear and tear, causing damage to the mating parts as well.

The contact state between the deformed sealing ring and the groove, as well as the shaft surface is abnormal. During normal operation, the sealing ring should "stick closely", with very little friction. After deformation, it becomes "pushing against each other for grinding", with local stress concentration. The sealing ring will quickly wear, age, or even tear. What's more troublesome is that the abnormal friction will also scratch the surface smoothness of the mating surface, causing scratches on the groove or the shaft surface. By then, replacing a new sealing ring will be useless because the mating surface has already been damaged and must be replaced together. The maintenance cost will directly double.

Thirdly, the deformation is irreversible and the elasticity has decreased.

When rubber materials undergo deformation, the internal molecular chain structure undergoes irreversible changes. In the industry, this is called "stress relaxation" or "permanent deformation". That is to say, if you leave it for a period of time, it may seem to "recover" to some extent, but in fact, its elasticity has significantly decreased. The next time it is subjected to pressure, its rebound force is insufficient, and its sealing reliability is much worse than that of a new piece. Therefore, there is no such thing as "it can continue to be used after being left alone".

Under what circumstances is it especially unacceptable to settle for something less?

If it occurs under conditions such as hydraulic systems, pneumatic systems, high-temperature and high-pressure environments, or in the presence of highly corrosive media, any degree of deformation must be considered as non-compliant and must be scrapped without any room for negotiation. This is because the requirements for sealing in these conditions are already very high and cannot tolerate any flaws.

Even in scenarios involving water supply, ordinary pipes and other low-pressure, low-temperature situations, slight deformation is not worth taking the risk of. Because the sealing ring is itself a low-value consumable part, ranging from a few dollars to several tens of dollars, the cost of replacing it is almost negligible. However, if doing so saves just this small amount of money leads to leakage, it will result in equipment downtime and environmental pollution in the mild cases, and even trigger safety accidents in the severe cases. In any case, this is not a cost-effective decision.

There are several key points to keep in mind when replacing.

First of all, it is essential to ensure that the model and size are exactly the same as the original. The inner diameter, outer diameter, and cross-sectional diameter must all match perfectly. Even a slight deviation could result in improper installation or excessive compression.

Secondly, the materials must match. Common ones include NBR (oil-resistant), FKM (high-temperature resistant and corrosion-resistant), EPDM (water-resistant and aging-resistant), and silicone rubber (high-temperature food-grade). Different media and temperatures require different materials. Using the wrong material will cause even the best sealing ring to fail very quickly.

Finally, during the installation process, do not forcefully insert with sharp tools to avoid causing secondary deformation during the installation. You can apply a little lubricating grease or vaseline on the surface of the sealing ring, which will not only facilitate the installation but also reduce the initial friction.

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