Summary Of The Main Causes Of Rubber Seal Failure

As a widely used sealing element in the industrial field, the performance and life of rubber sealing rings directly affect the safety and reliability of mechanical equipment. However, in practice, rubber seals often fail for a variety of reasons, leading to leaks, mechanical failures, and even equipment damage. The following is an in-depth analysis of the main causes of the failure of rubber seals from multiple perspectives such as materials, design, processing, use conditions,s, and external environment.

Material reasons

The performance of rubber seals is highly dependent on the physical and chemical properties of the material and its compatibility with the working medium. If the material is not selected properly, the seal may fail due to various chemical and mechanical actions.

The materials are incompatible

Rubber materials need to be adapted to the medium (e.g., oil, water, gas) and the working environment (e.g., temperature, humidity, chemicals). If the material is not selected correctly, the following problems may occur:

Swelling or dissolving: Seals can swell when exposed to certain oils, solvents, or chemicals, resulting in dimensional changes or reduced strength.

Hardening or softening: Chemical incompatibility can cause the rubber to harden (lose elasticity) or soften (lose structural strength).

Degradation or decomposition: Some rubbers decompose when exposed to high temperatures or oxidation (e.g., natural rubber is cracked under the action of ozone).

Aging of rubber materials

In long-term use, the performance of rubber materials will deteriorate due to aging, which is mainly manifested as decreased elasticity, increased hardness, and surface cracking. The main causes of aging include:

Thermal aging: At high temperatures, the molecular chains of rubber undergo thermal oxidative degradation, resulting in the loss of mechanical properties.

Oxidative aging: Oxygen reacts with double bonds in rubber molecules, causing the material to break down.

Ozone aging: Ozone causes cracks on the rubber surface, especially under dynamic conditions.

Ultraviolet aging: Ultraviolet rays from sunlight can trigger the degradation of rubber surfaces.

 Migration of material additives

Plasticizers, antioxidants, fillers, etc. added to the rubber may migrate to the surface under high temperatures and medium, thereby changing the properties of rubber, such as hardening, cracking, etc.

Design reasons

The design stage has an important impact on the failure of rubber seals, and unreasonable design may lead to insufficient sealing performance or even failure.

The design of the sealing structure is unreasonable

Excessive compression: Excessive compression of rubber seals may result in permanent deformation or tearing.

Insufficient compression: If the compression is too small, an effective seal cannot be formed.

Stress concentrations: Angular or unsmooth surfaces in the design can cause stress concentrations that can make seals susceptible to damage.

Tolerance matching issues

Unreasonable tolerances between the rubber seal and the mating may result in the seal not fitting effectively. Too loose can cause leaks, and too tight can increase frictional losses or tear the seal.

The cross-sectional size of the sealing ring is selected incorrectly

If the cross-sectional size of the sealing ring is too small, it cannot withstand high pressure; If it is too large, it may increase the difficulty of assembly and frictional losses in operation.

Ignore dynamic conditions

Failure to fully consider sealing requirements in motion (e.g., reciprocating, rotating) in the design can lead to excessive friction or insufficient wear resistance, which can accelerate failure.

Processing and manufacturing reasons

Process issues in the sealing manufacturing process are also significant contributors to failure.

Material formulation issues

The performance of rubber seals depends on the proportion of each component in the material formulation. Improper formulation design, such as the wrong amount of vulcanizer or filler, can result in substandard seal performance.

Improper vulcanization process

Insufficient vulcanization will make the rubber less elastic, and excessive vulcanization will lead to increased brittleness or accelerated aging.

Dimensional deviation

Insufficient machining accuracy may lead to the size of the sealing ring not matching the design, affecting the sealing performance.

Surface defects

Defects such as porosity, cracks, and burrs on the surface of the rubber seal will lead to reduced sealing performance, and even cause stress concentration to lead to early failure.

Reasons for the conditions of use

The failure of rubber seals in practical applications may also be closely related to the conditions of use.

Temperature overrun

Rubber materials have a temperature range, beyond which they can lead to a drastic drop in performance:

High-temperature environment: This leads to thermal aging of materials, decreased elasticity, and increased hardness.

Low-temperature environment: Cause rubber embrittlement or vitrification, loss of sealing effect.

Excessive pressure or fluctuating pressure

In a high-pressure environment, the seal may be extruded or deformed to fail; Pressure fluctuations can lead to fatigue damage.

Movement speed and friction problems

Dynamic seals can wear out, deteriorate, or fail prematurely due to the accumulation of frictional heat at high speeds or in frequent movements.

Contamination of the working medium

The presence of particles or impurities in the working medium may cause abrasion or scratches on the surface of the sealing ring.

External environmental factors

External environmental conditions also have a significant impact on the service life and performance of rubber seals.

1. Chemical erosion

Corrosive chemicals (e.g., acids, alkalis, salt solutions) can have an aggressive effect on rubber seals, causing them to decompose or degrade their properties.

2. Mechanical damage

Mechanical damage (e.g. scratches, cuts) during installation or maintenance can be the starting point for failure.

3. Particulate pollutants

Contamination from outside particles can become embedded in the sealing surface, causing scratches or abrasion.

4. Electrochemical interactions

Electrochemical reactions in special environments, such as sealing applications in conductive liquids, can accelerate the aging or damage of rubber.