Expansion Joint Rubber
Introduction :
Expansion joints are essential components in construction and engineering, designed to accommodate movement caused by temperature changes, settling, or other stresses. Among the various materials used for these joints, rubber stands out due to its unique properties. This article delves into the benefits, types, and applications of expansion joint rubber, highlighting its significance in various industries.
Key Benefits of Rubber Expansion Joint
Rubber expansion joints are designed to allow for significant movement up to 30 mm and angel up to 20⁰ due to thermal expansion, contraction, and structural settling. This flexibility helps prevent cracks and structural damage.
Rubber effectively absorbs vibrations and shocks, protecting the integrity of structures and extending the lifespan of equipment and joints.
High-quality rubber is resistant to wear, chemicals, and UV exposure, making it suitable for both indoor and outdoor applications. This durability ensures that the joints remain effective over time, even under harsh conditions.
The acoustic dampening properties of rubber help to minimize sound transmission, making environments more comfortable, particularly in industrial and commercial settings.
By preventing damage and maintenance costs, expansion joint rubber is a cost-effective solution in the long run. Its durability and performance reduce the need for frequent replacements.
Many rubber expansion joints are designed for straightforward installation, which can help reduce labor costs and project timelines.
Types of Rubber Expansion Joint
1. Neoprene
Known for its excellent weather resistance and durability, neoprene is commonly used in outdoor applications.
2. EPDM (Ethylene Propylene Diene Monomer)
This type of rubber is highly resistant to heat, ozone, and weathering, making it ideal for roofing and construction applications.
3. SBR (Styrene-Butadiene Rubber)
Often used for its good resilience and cost-effectiveness, SBR is suitable for various general-purpose applications.
Codes & Standard
International Codes & Standards
- ASME B16.1 Cast Iron Pipe Flanges and Flanged Fittings (Cl.125 Sizes 1”-24”)
- ASME B16.5 Steel Pipe Flanges and Flanged Fittings (Cl.150 Sizes 1”-24”)
- ASME B16.47 A Steel Pipe Flanges and Flanged Fittings (Cl.150 Sizes 26”-60”)
- AWWA C207 Steel Pipe Flanges for Waterworks Service (Sizes 66”-144”)
- FSA Fluid Sealing Association – Expansion Joint Piping Division
- EJMA Expansion Joint Manufacturers Association
- ASME B31.1 Code for Power Piping (where applicable to rubber expansion joints)
- ASME B31.3 Code for Process Piping (where applicable to rubber expansion joints)
- ASTM F1123-87 Standard Specifications for Non Metallic Expansion Joints
- ISO 9001 Quality Management Standard
- ISO 14001 Environmental Management Standard
- ASTM D2000 Standard Classification System for Rubber Products
- ASTM D1418 Standard Practice for Rubber and Rubber Latices-Nomenclature
- ASTM D2240 Standard Test Method for Rubber Property – Durometer Hardness
- ASTM D412 Standard Test Methods for Vulcanized Rubber – Tension
- ASTM D297 Standard Test Methods for Rubber Product – Chemical Analysis
- ASTM D471 Standard Test Method for Rubber Property – Effect of Liquids
- ASTM D573 Standard Test Method for Rubber – Deterioration in an Air Oven
- ASTM D395 Standard Test Method for Rubber Property – Compression Set
Performance Table
All expansion joints shall have a minimum burst pressure of three times the design pressure. The design shall be substantiated by detailed stress analysis such as the finite element method or other sound engineering practice. Additionally, the design should have successful service experience under comparable conditions for similar components of the same or like material.
Pressure and vacuum ratings for the rubber expansion joints shall be as shown below. Hydrostatic pressure test shall be performed at 1-1/2 times the design pressure. Vacuum tests shall be performed at 26” hg due to site elevation and equipment limitations. The duration of each of these tests shall be 10 minutes unless otherwise specified. These non-destructive tests can be witnessed by the customer or authorized third party when ordered. Higher design pressures are available upon request.
| Pipe Size (in.) | GTE FF (in.) | Design Pressure (psg) | Design Vacuum (in.hg) |
| 2-8 | 6 | 220 | 30 |
| 10-14 | 8 | 220 | 30 |
| 16 -18 | 8 | 160 | 30 |
| 20 | 8 | 160 | 30 |
| 24 | 10 | 160 | 30 |
| 30 | 10 | 100 | 30 |
| 36 | 10 | 90 | 30 |
| 42 – 48 | 12 | 90 | 30 |
| 54 – 72 | 12 | 85 | 30 |
| 78 – 96 | 12 | 80 | 30 |
| 102 – 108 | 12 | 60 | 30 |
Rated temperatures for rubber expansion joints, shown below, are dependent on both the elastomer and reinforcement limitations. The tube selection should also be based on the chemical, corrosive, and/or abrasive nature of the media. The cover selection should also be based on the external environment. For air service at 25 psig maximum EPDM/Polyester and Butyl/Polyester are rated for 300ºF.
Inspection & Testing
Manufacturer shall upon request prepare a detailed inspection and test plan for approval. The test plan shall include test details, frequency, acceptance criteria, and applicable codes and standards. Hold points and review of documentation can be witnessed by the customer and/or authorized third party when ordered.
Visual and dimensional inspection shall verify that the tolerances are within specified allowable. The tube and cover shall be free of structural defects.
Small depressions and indentations are acceptable as long as the surface of the elastomer is not broken. Surface blemishes, such as flash, nylon wrap markings, grooves, and other indentations in the cover are acceptable.
The American Society for Testing and Materials technical testing standards, ASTM D2240, ASTM D412, ASTM D297, ASTM D471, ASTM D573 and ASTM D395 are to be performed annually on each batch of compound manufactured to assure conformance to the specific ASTM D2000 classification line call outs for each elastomer as listed below. Appropriate documents shall be available to the customer upon request.
Elastomers
- EPDM (EPR) – M4CA 607 A25 C32 EA14 Z1 Z2
- Neoprene (CR) – M3BC 610 A14 Z1
- Chlorobutyl (IIR)- M2BA 607 Z1 Z2
- Nitrile/Buna-N (NBR) – M5BG 610 A14 B14 EO34 Z1
- Hydrogenated Nitrile (HNBR) – M2DH7
- Pure-Gum Rubber (NR) – M2AA 4 14 Z1 Z2 Z3
- PTFE (Fluoroplastic) – NA
- Fluoroelastomer (FKM) – M2 HK 6 10 A1-10 B37 C12 Z1 Z2 Z3 Z4
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