Calculation and Design Standards
Design and calculation standards are well-established and widely recognized, often following industry standards such as EJMA (Expansion Joint Manufacturers Association), ASME (American Society of Mechanical Engineers) and European Standards.
Design and calculation standards are available but may not be as standardized or universally accepted as those for metal expansion joints. Engineers may need to rely on manufacturer-specific data and guidelines, which can vary between suppliers. The Fluid Sealing Association handbook is a compilation of standards of construction and a guide for rubber non-metallic expansion joints.
Temperature Resistance
Suitable for high-temperature applications, often exceeding °C ( °F).
Limited temperature resistance, typically up to 150 °C (300 °F) or lower.
Pressure Resistance
Excellent pressure resistance, suitable for high-pressure systems.
Moderate pressure resistance, suitable for low to moderate-pressure systems.
Corrosion Resistance
Good resistance to corrosion, especially when made from stainless steel and other corrosion resistance metals.
Good corrosion resistance properties but is vulnerable to corrosion in aggressive environments.
Chemical Resistance
Can be designed for specific chemical resistance but may require additional coatings or linings or special materials.
Can be chemically resistant depending on the rubber material but may degrade over time in aggressive chemicals. PTFE lining is possible.
Fire Resistance
Offers good fire resistance.
Varies based on rubber material; may not provide fire resistance.
Resistance to Abrasion
Resistant to abrasion, suitable for applications with abrasive/erosive media using right materials and/or linings.
Vulnerable to abrasion and may wear out faster in abrasive environments.
Chemical Compatibility
Can be customized for specific chemical compatibility but may require additional measures.
Limited chemical compatibility compared to metals; may deteriorate in the presence of certain chemicals.
UV Resistance and Sunlight Exposure
Resistant to UV radiation and sunlight exposure. Suitable for outdoor applications.
Susceptible to UV radiation and sunlight exposure, may require protective measures.
Ozone Resistance
Unaffected by ozone exposure. Ozone does not pose a significant threat.
Vulnerable to ozone exposure, requiring ozone-resistant rubber in certain environments.
Heat Aging
Resistant to heat aging, maintaining structural integrity at high temperatures.
Vulnerable to heat aging, which can lead to hardening and deterioration over time.
Movement Absorption Capacity
Good for absorbing axial, lateral, and angular movements.
Excellent for absorbing axial, lateral and angular movements.
Flexibility
Higher spring rates than rubber expansion joints. Provides limited flexibility compared to rubber, which may restrict movement in some cases.
Lower spring rates. Highly flexible and capable of accommodating a wide range of movements.
Noise and Vibration Control
Limited noise and vibration control capabilities.
Excellent noise and vibration damping characteristics.
Shock Absorption
Limited shock absorption capabilities.
Excellent shock absorption properties, making them suitable for systems with frequent pressure surges or shocks.
Longevity
Long service life, often exceeding 20 years or more with proper maintenance.
Relatively shorter service life, typically 5-10 years.
Maintenance
Low maintenance required, occasional inspection and tightening of bolts.
May require more frequent inspections and replacement due to wear and tear.
Cost
Typically more expensive upfront but cost-effective over the long term due to durability.
Lower initial cost but may incur higher replacement and maintenance costs.
Installation
Often requires skilled labor for welding and proper alignment.
Easier and faster installation, suitable for various connection methods.
Weight
Heavier than rubber expansion joints, which can affect structural support requirements.
Lighter weight, which may reduce structural support needs.
Cleanliness and Hygiene
Suitable for applications where cleanliness and hygiene are required selecting the right materials, cleaning procedures, specific linings, etc.
Ideal for applications in the food, pharmaceutical and sanitary industries due to their smooth, non-porous surfaces always selecting the right internal elastomer or lining.
Cost of customization
Custom designs and materials can increase costs significantly.
Easily customizable with various rubber compounds, reducing customization costs.
Accessibility for site inspection
May be challenging to inspect due to their complexity in some cases.
Easier to inspect without the need for disassembly in most cases.
Compatibility with ancillary equipment
May require additional engineering for compatibility with ancillary equipment.
Typically more straightforward to integrate with other system components.
Welding and Fabrication
Require skill welding during fabrication and generally during installation.
Typically, no welding or fabrication skills are needed for fabrication and installation.
Electrical Conductivity
Metals are good electrical conductors, so metal expansion joints can conduct electricity. This property can be an advantage or disadvantage depending on the application.
Rubber is an insulator and does not conduct electricity, making rubber expansion joints suitable for applications where electrical conductivity is a concern.
The raw materials for rubber expansion joints include EPDM rubber, nitrile rubber, chloroprene rubber, natural rubber, fluororubber, etc. The following will introduce the characteristics and advantages of each material.
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1. EPDM expansion joint
Excellent comprehensive performance, with ozone resistance, weather resistance, high temperature resistance, low temperature resistance, chemical resistance, multiple solute resistance, and low relative density. The disadvantage is that it has a large expansion in general oils and lubricants, and is generally dark colored products. The temperature range of use is -60~+150 ', which is suitable for high temperature, high cold, coastal areas, areas with strong ultraviolet radiation, and mid to high-rise buildings. It has a wide range of applications and superior comprehensive performance.
2. Neoprene expansion joint
Compared with other rubbers, some of them have poorer performance, but the overall performance balance is good. They have excellent weather resistance, ozone resistance, heat aging resistance, oil and solvent resistance, good chemical resistance, excellent flame resistance, good adhesion, poor storage stability, and may experience hardening during storage, resulting in poor cold resistance. Relatively dense, generally black, suitable for oil and heat resistant environments, suitable for temperature ranges of -30~+120 '.
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3. NBR expansion joint
The main characteristics are oil and solvent resistance, but it is not resistant to media such as ketones, lipids, and chlorinated hydrocarbons. Its elasticity and mechanical properties are good, but its disadvantages are easy aging and cracking in ozone and oxidation, poor cold resistance, and low temperature resistance. The temperature range for use is -30~+120 '
4. Fluorine rubber expansion joint
Fluorine rubber (FPM) is an organic elastomer formed by copolymerization of fluorinated monomers, characterized by high temperature resistance up to 300 ', acid and alkali resistance, oil resistance, radiation resistance, and good vacuum resistance; Electrical insulation, mechanical performance, chemical corrosion resistance, ozone resistance, and atmospheric aging resistance are all excellent, but the disadvantages are poor processability, expensive price, poor cold resistance, low elasticity and breathability, and the use temperature range is -20~+200 '