Rubber Bellows and Expansion Joints
Custom-manufactured technical rubber flexible components to solve the three problems that rigid pipework and ducting cannot absorb: thermal expansion, equipment vibration and misalignment between connection points. Unlike metallic expansion joints, rubber joints absorb movement in all directions simultaneously, dampen noise and vibration, resist corrosion and recover their original shape without permanent deformation. Manufactured in silicone, EPDM, neoprene, Viton® or natural rubber according to the fluid and service temperature.
When a pipe heats up, it expands. When a fan or pump operates, it generates vibrations that are transmitted to the installation. When two sections of pipe or duct are not perfectly aligned, stresses are generated at the connections. These three problems — thermal expansion, mechanical vibration, misalignment — are solved with a flexible component that absorbs the movement without transmitting it to the rest of the installation.
Rubber expansion joints fulfil this function with significant advantages over metallic joints: they absorb movement in all directions (axial, lateral and angular) simultaneously, dampen vibrations and noise transmitted by the fluid, do not corrode, do not generate sedimentation and recover their original shape after each cycle of movement. The cost is significantly lower than equivalent metallic joints.
The elastomer material is selected according to the fluid and service temperature — exactly the same logic as for a flat gasket. EPDM for water and steam, neoprene for light oils and weathering, Viton® for hydrocarbons and aggressive chemicals, silicone for high temperature, natural rubber for maximum elasticity and abrasion resistance. The internal reinforcement (nylon, aramid or steel fabric plies) is sized according to the working pressure.
Rubber or metallic expansion joint?
The rubber joint is the best option when: vibration and noise absorption is needed (pumps, fans, compressors), the fluid is corrosive and would attack a metallic joint, multi-directional simultaneous movement is required, or the budget is limited. The metallic joint is preferable when: the temperature exceeds 200 °C, the pressure exceeds 25 bar, or regulations require a metallic joint (as in some pressure codes). In most HVAC, water, chemical process and pumping installations, the rubber joint is the smartest solution.
Quick selection by application
Locate your application and the recommended configuration.
| Requisito | Formulación | Serie | Proceso |
|---|---|---|---|
| Thermal expansion in water/HVAC pipework | Single-arch spool | EPDM | Custom manufacture + DIN/ANSI flanges |
| Pump or compressor vibration isolation | Double sphere | EPDM or neoprene | Floating galvanised-steel flanges |
| Fan/duct HVAC flexible connection | Rectangular | Neoprene or EPDM | Integrated flange or frame |
| Chemical process pipework with aggressive fluids | Spool (1–3 arches) | Viton® or EPDM | Custom manufacture + documentation |
| Pipework with slurries or abrasive fluids | Filled-arch spool | Natural rubber | Filled arch anti-sediment |
| Marine installation / seawater + oils | Spool | Neoprene | Custom manufacture |
| High temperature (hot air, fumes) | Rectangular or spool | Silicone | Custom manufacture |
| Replacement of obsolete/discontinued joint | Custom bellows | Per fluid | Reverse engineering + manufacture |
Every installation requires its own configuration
Spool-type (arch) expansion joint
The most widely used configuration in industrial pipework. A flexible arch (or multiple arches for greater movement) between two flanges. Absorbs compression, extension, lateral and angular movement. Available in single, double or triple arch. With or without filled arch (to reduce turbulence and sedimentation). Internal fabric reinforcement with steel rings at the flanges for high-pressure sealing. Diameters from DN 25 to DN 3,600.
Spherical flexible connector
Spherical-design expansion joint with floating galvanised-steel flanges for easy alignment. The spherical profile distributes internal pressure uniformly — more resistant and more compact than the traditional cylindrical profile. Reduces turbulence and sediment accumulation. Available in single and double sphere. For pump and fan connections where the primary objective is to absorb vibration and noise.
Rectangular / duct expansion joint
Expansion joint for rectangular or large-diameter circular air, gas and fume ducts. Integrated rubber flanges or for frame mounting. For flexible connections on fans and blowers, HVAC ducts and industrial chimneys where fan vibrations must be isolated from the ductwork.
Custom bellows / special shape
Custom-manufactured rubber bellows for applications that do not fit standard configurations. Conical, eccentric, reducing shapes, special connections or non-circular geometries. Handcrafted by layering elastomer and reinforcement fabric to customer specification. For OEM applications, special machinery and replacement of obsolete parts.
From DN 25 to DN 3,600 — any size, any flange
Every expansion joint is manufactured to the exact dimensions of the installation. The diameter, body length, flange standard (DIN, ANSI, BS, EN) and bolt-hole pattern are defined according to line conditions.
Small diameter: DN 25 – DN 100
DN 25 to DN 100For instrumentation pipework, small-diameter process lines, laboratory pump connections. Generally spherical or single-arch spool type.
- Diameters
- DN 25 · 32 · 40 · 50 · 65 · 80 · 100
- Pressure
- Up to 16–25 bar depending on design
- Flange
- DIN, ANSI, EN, threaded
Materials: EPDM, neoprene, Viton®, silicone.
Medium diameter: DN 125 – DN 600
DN 125 to DN 600The most widely used range in industrial installations. Water networks, HVAC circuits, process pipework, pumping systems. Spool type (single or double arch) or spherical.
- Diameters
- DN 125 · 150 · 200 · 250 · 300 · 400 · 500 · 600
- Pressure
- Up to 16 bar standard, 25 bar by design
- Flange
- DIN PN10/16, ANSI 150#/300#, EN
Materials: EPDM, neoprene, Viton®, natural rubber.
Large diameter: DN 700 – DN 3,600
DN 700 to DN 3,600For large water mains, process headers, industrial ducts and large-format equipment connections. Custom manufacture with internal reinforcement sized to working pressure.
- Diameters
- DN 700 to DN 3,600 (custom manufacture)
- Pressure
- Per design
- Flange
- Per customer specification
Materials: EPDM, neoprene, natural rubber.
Reducing joints (concentric and eccentric) available for connection of different-diameter pipes. Control rods available as an accessory to limit extension under pressure.
The right elastomer for every fluid
Elastomer selection by fluid and temperature
Five elastomers cover virtually any industrial application. Correct material selection is the most important factor for the service life of the expansion joint.
Material specification reference.
| Material | Temperature | Compatible fluids | NOT compatible fluids |
|---|---|---|---|
| EPDM | –50 to +150 °C | Water, steam, acids, bases, ketones | Oils, fuels, hydrocarbons |
| Neoprene (CR) | –35 to +120 °C | Water, light oils, refrigerants, weathering | Aromatic hydrocarbons, ketones |
| Viton® (FKM) | –25 to +200 °C | Hydrocarbons, oils, fuels, acids | Ketones, amines, steam > 150 °C |
| Silicone (VMQ) | –60 to +200 °C | Hot air, hot water, food products | Steam > 150 °C, hydrocarbons, strong acids |
| Natural rubber (NR) | –50 to +80 °C | Cold water, air, dilute acids, abrasives | Oils, ozone, UV, temperature > 80 °C |
EPDM is the standard material for water and HVAC. Neoprene for marine and installations with light oils. Viton® for chemical and petrochemical. Silicone for high temperature and food-grade. Natural rubber for maximum elasticity and abrasion resistance (slurries, sands).
Internal reinforcement — pressure and movement
The body of the expansion joint is formed by alternating layers of elastomer and reinforcement fabric (nylon, polyester, aramid). The number of plies and the fibre type determine the maximum working pressure. The metal rings at the flanges provide the seal and fixation.
Technical reference for installation design.
| Reinforcement | Typical pressure | Application |
|---|---|---|
| 2-ply nylon | Up to 10 bar | HVAC, low-pressure water, fan connections |
| 3–4-ply nylon | Up to 16 bar | Industrial water, standard chemical process |
| 4–6-ply aramid | Up to 25 bar | High pressure, pumping, chemical process |
| Aramid plies + steel rings | Up to 40 bar | High-pressure installations, special applications |
The number of arches also affects movement capacity: more arches = more movement but greater overall length. Filled arches reduce movement by ~50% but eliminate turbulence and sediment accumulation.
Five elastomers cover virtually any industrial application. Correct material selection is the most important factor for the service life of the expansion joint.
Material specification reference.
| Material | Temperature | Compatible fluids | NOT compatible fluids |
|---|---|---|---|
| EPDM | –50 to +150 °C | Water, steam, acids, bases, ketones | Oils, fuels, hydrocarbons |
| Neoprene (CR) | –35 to +120 °C | Water, light oils, refrigerants, weathering | Aromatic hydrocarbons, ketones |
| Viton® (FKM) | –25 to +200 °C | Hydrocarbons, oils, fuels, acids | Ketones, amines, steam > 150 °C |
| Silicone (VMQ) | –60 to +200 °C | Hot air, hot water, food products | Steam > 150 °C, hydrocarbons, strong acids |
| Natural rubber (NR) | –50 to +80 °C | Cold water, air, dilute acids, abrasives | Oils, ozone, UV, temperature > 80 °C |
EPDM is the standard material for water and HVAC. Neoprene for marine and installations with light oils. Viton® for chemical and petrochemical. Silicone for high temperature and food-grade. Natural rubber for maximum elasticity and abrasion resistance (slurries, sands).
The body of the expansion joint is formed by alternating layers of elastomer and reinforcement fabric (nylon, polyester, aramid). The number of plies and the fibre type determine the maximum working pressure. The metal rings at the flanges provide the seal and fixation.
Technical reference for installation design.
| Reinforcement | Typical pressure | Application |
|---|---|---|
| 2-ply nylon | Up to 10 bar | HVAC, low-pressure water, fan connections |
| 3–4-ply nylon | Up to 16 bar | Industrial water, standard chemical process |
| 4–6-ply aramid | Up to 25 bar | High pressure, pumping, chemical process |
| Aramid plies + steel rings | Up to 40 bar | High-pressure installations, special applications |
The number of arches also affects movement capacity: more arches = more movement but greater overall length. Filled arches reduce movement by ~50% but eliminate turbulence and sediment accumulation.
From your installation specification to the expansion joint installed
Every expansion joint is a custom-manufactured component. The process begins with the analysis of the installation conditions and ends with the delivery of the component ready to install.
Application sectors
General Industry
Expansion joints for water networks, HVAC, pumping and industrial process pipework.
Rail
Flexible connectors for HVAC, cooling and piping circuits on rolling stock.
Nuclear
Expansion joints for cooling circuits and process pipework in nuclear power stations.
Food & Beverage
Food-grade silicone bellows for flexible connections on processing and CIP lines.
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EPDM Sheet
The same material as your EPDM expansion joints, in sheet form.
Neoprene Sheet
The same material as your neoprene expansion joints, in sheet form.
Need an expansion joint or custom bellows?
Tell us: the line fluid, the service temperature and pressure, the pipe or duct diameter, the flange standard, the movements to be absorbed (compression, extension, lateral, angular) and any special requirements. If it is a replacement, send us photos and dimensions of the existing joint. We provide a technical solution and quotation.
Request quotation