AYVAZ

RUBBER EXPANSION JOINTS

For more information, please visit Sanshi.

Rubber expansion joint is a flexible connector fabricated of natural and/or synthetic elastomers and fabric, if necessary, internal metallic reinforcements designed to provide stress relief in piping systems due to thermal movements and mechanical vibration.

There are lots of material selection based on usage area of rubber expansion joints. Also rubber expansion joints have advantages and disadvantages between of the metal expansion joints. Rubber expansion joints can absorb large movement in very short distance. They provide all directional movement, such as axial, angular, lateral and torsional that may occur from external conditions. Also reduce wind, shock loading and seismic movements. 

APPLICATION AREAS

' Heating and cooling devices
' Materials handling technologies
' Water pipes
' Desalination plants
' Compressors
' Blowers and fans
' Cement industry
' Chemical industry
' Glass industy
' Wood-processing industry
' Pulp and paper industry
' Railed vehicles
' Refineries
' Shipbuilding
' Steel mills
' Sugar industry

ADVANTAGES

Spherical joints have a distinct advantage over metallic expansion joints for corrosive applications and installations requiring a high cycle life. The contour prevents sediment accumulation and creates less turbulence and pressure drop than spool joints. The seal bead eliminates any requirement for gaskets between mating flanges. Spheres may be installed on raised-face or flat-face flanges.

COMPARISON AGAINST METAL EXPANSION JOINTS

Temperature: Rubber joints with standard construction and materials have an upper range to 110°C. Can be offer special constructions up to 200°C. Metal expansion joints do offer a far greater range, from -250°C to +950°C. 

Pressure: Rubber joints depending on diameter, can have pressure capabilities up to 15 bar with a full vacuum rating. Metal joints can be designed for pressures up to 100 bar. 

Movements: Rubber and metal expansion joints have similar movement capabilities in the axial plane (compression and extension). However, rubber joints are certainly able to absorb greater lateral movements when compared to metal joints that have similar face to face lengths.

Spring Rates: Rubber and metal joints do have similar characteristics in the axial plane for the standard face to face dimensions. Metal joints are much stiffer when subjected to lateral motion and, typically have a  lower lateral movement capability. 

Acoustical Impedance: Although well designed (multi-ply) metal joints can lower the transmission of visible vibration, they will continue to transmit distracting and/or damaging noise. Rubber joints significantly reduce the undesirable transmission in piping systems. The elastomeric composition of the joint acts as a dampener that absorbs the greatest percentage of perceptible noise and vibration.

Abrasion/Erosion Resistance: Metal joints typically have a wall thickness anywhere between 0.15mm to 2mm. Rubber joints are much thicker, 12mm to over 25mm. The thin construction of metal joints makes them susceptible to erosive chemicals and abrasive liquids and slurries. Rubber joints are highly resistant to abrasion and erosion of all types and outperform metal joints in the applications where these conditions prevail.

Fatigue/Cycle Life: The fatigue life of a metal joint is affected by many factors such as temperature, pressure, movement, vibration and how the joint was initially designed. Typically, metal joints have a defined cycle or fatigue life that can be calculated through various formulas (EJMA). Metal joints frequently succumb to fatigue failure from excessive cycling/movement. Rubber joints on the other hand are constructed of resilient elastomers and the joint itself acts as a vibration dampener, not susceptible to fatigue/cycle failure.

Installation/Maintenance: Rubber joints do not require additional gasketing and, in many cases, are installed without the use of special handling equipment. Metal joints must be serviced occasionally to insure that the flange gasket is still intact and not deteriorated

MATERIAL SELECTION

Material selection of rubber expansion joints are very variable and depends on the pressure, temperature, fluid etc. parameters. The common materials are, EPDM, IIR, NBR, PTFE and combined with these materials depends of usage area. Also the inner tube and outer tube's diameter can be different depends of design conditions. 

Table I: Maximum Temperature Ratings Reinforcing Fabric Tube or Cover Elastomer Pure Gum Rubber Neoprene Butyl Nitrile Hypalon® EPDM FKM Nylon 180 °F / 82 °C 225 °F / 107 °C 250 °F / 121 °C 210 °F / 99 °C 250 °F / 121 °C 250 °F / 121 °C 250 °F / 121 °C Polyester 180 °F / 82 °C 225 °F / 107 °C 250 °F / 121 °C 210 °F / 99 °C 250 °F / 121 °C 250 °F / 121 °C 250 °F / 121 °C Aramid 180 °F / 82 °C 225 °F / 107 °C 300 °F / 149 °C 210 °F / 99 °C 250 °F / 121 °C 300 °F / 149 °C 400 °F / 204 °C

 

Table II. List of Elastomers Used in Expansion Joints and Rubber Pipes MATERIAL
DESIGNATION RATING SCORE CODE ELASTOMER PHYSICAL AND CHEMICAL PROPERTIES COMPARISON ANSI/ASTM
D-77 ASTM-D-
D-77 7-Outstanding
6-Excellent
5-Very Good
4-Good
3-Fair to Good
2-Fair
1-Poor to Fair
0-Poor
X-Contact Mfg. ALKALI, CONC.
ANIMAL VEG. OIL
CHEMICAL
WATER OXYGENATED HYDRO.
LACQUERS
OIL & GASOLINE
ALKALI, DILUTE ACID DILUTE
ACID, CONC.
ALPHATIC HYDRO
AROMATIC HYDRO ELE. INSULATION
WATER ABSORP
RADIATION
SWELLING IN OIL REBOUND-COLD
COMP. SET
TENSILE STRENGTH
DIELECTRIC STR. ABRASION
IMPERMEABILITY
DYNAMIC
REBOUND-HOT HEAT
COLD
FLAME
TEAR OZONE
WEATHER
SUNLIGHT
OXIDATION COMMON NAME
CHEMICAL GROUP NAME CR BC BE NEOPRENE
CHLOROPENE 4 3 4 0 4 4 0 1 2 3 4 6 4 5 4 3 5 4 2 4 5 2 4 5 4 4 4 4 5 5 6 5 NR AA GUM RUBBER
POLYISOPRENE, SYNTHETIC 5 3 X X X 0 0 4 0 0 3 3 0 6 5 5 6 6 4 6 6 6 2 7 5 0 5 2 4 0 2 0 IR AA NATURAL RUBBER
POLYISOPRENE, SYNTHETIC 5 3 X X X 0 0 4 0 0 3 3 0 6 5 5 6 6 4 6 6 2 2 6 5 0 5 2 4 0 2 0 IIR AA BUTYL
ISOBUTENE-ISOPRENE 5 6 5 4 4 0 3 4 0 0 4 6 0 4 5 5 4 3 0 5 2 6 4 4 0 4 5 6 5 5 6 FKM HK FLUOROCARBON
ELASTOMER 5 6 6 0 4 6 1 0 6 6 6 5 6 5 5 3 5 5 6 2 4 5 5 5 2 6 2 7 7 7 7 7 EPR BA CA DA EPDM
ETHYLENE-PROPYLENE-
DIENE-TERPOLYMER 5 6 5 6 6 0 3 6 0 0 4 6 0 7 6 6 7 5 4 6 6 5 4 5 4 0 5 6 6 7 6 7 AFMU   PTFE/TFE/FEP
FLUORO-ETHYLENE-
POLYYMERS 7 7 7 7 7 7 7 7 7 7 7 7 7 3 7 X X X X X X X X 4 X X X 7 7 7 7 7 SI GE SILICONE 5 5 5 0 2 X 0 2 0 0 2 6 2 5 6 6 4 0 3 6 6 0 2 0 2 2 6 7 6 6 6 6

 

TYPES OF RUBBER EXPANSION JOINTS

ARCH TYPE:

A full face integral flange design is available in both Single Arch and Multiple Arch Types.

If you are looking for more details, kindly visit Rubber Joints.

Additional reading:
What kind of hose do I need for a bilge pump?

Single Narrow Arch Type: 

Smooth Surface 10000 Psi 3/8" Hydraulic Jack Hose For ...
The Ultimate Guide to Choosing the Right Hose Crimping ...
Is a Belt Press or Plate and Frame Filter Press the Right ...
When to Use 5 layers a/c hose factories？
Tire Cord Fabrics Market Global Forecast to 2023
In-Depth Guide to Industrial Hose Manufacturing Processes

Construction is of fabric and rubber, reinforced with metal rings or wire. The full face flanges are integral with the body of the joint and drilled to conform to the bolt pattern of the companion metal flanges of the pipeline.

This type of rubber face flange is of sufficient thickness to forma tight seal against the metal flanges without the use of gaskets.

Multiple Narrow Arch Type: 

Joints with two or more arches may be manufactured to accommodate movements greater than those of which a Single Arch Type joint is capable.

 Multiple Arch joints of most manufacturers are composites of standard sized arches and are capable of movements of a single arch multiplied by the number of arches.

PTFE Lined

Spool Arch Type joints are available in many standard pipe sizes with Fluoroplastic liners of TFE and/or FEP. These liners are fabricated as an integral part of the expansion joint during manufacture and cover all wetted surfaces in the tube and flange areas. Fluoroplastic provides exceptional resistance to almost all chemicals within the temperature range of the expansion joint body construction. 

Non-metallic Reinforced Design

Constructed similar to the Spool 'Arch' Type except the carcass does not contain wire or metal ring reinforcement. Pressure resistance is accomplished through the use of special external flanged retaining rings furnished with the joint.

Reducer Type

Reducing expansion joints are used to connect piping of unequal diameters. They may be manufactured as a concentric reducer with the axis of each end concentric with each other or as an eccentric reducer having the axis of each end offset from each other. Tapers in excess of 20 degrees are not desirable.

Sleeved Arch Type

This joint is similar to the 'Arch'typeexcept that the capped sleeve ends have an I.D. dimension equal to the O.D. of the pipe. These joints are designed to slip over the straight ends of the open pipe and be held securely in place with clamps. This type of joint is recommended only for low to medium pressure and vacuum service because of the difficulty of obtaining adequate clamp

Rubber Expansion Joints are defined as connectors between vessels or used in all systems transporting fluids, slurries or gases operating under pressure at widely different temperatures. These rubber expansion joints are installed in air and gas duct systems in all power plants, gas turbine systems, diesel engine installations, petrochemical and chemical plants, pump systems, cement works, steel works, incinerators, on- and offshore systems, ships and cruise vessels, etc.

Rubber expansion joints are used widely in most energy and industrial plants today. Made from natural or synthetic elastomers, rubber expansion joints are vital components used as flexible connectors in which special fabrics are embedded to provide physical reinforcement. They are used in a variety of applications. Rubber expansion joints are available in standard sizes or customized to the customer's individual needs from a variety of high quality synthetic rubber materials.

Uses of Rubber Expansion Joints

In a relatively short space, rubber expansion joints provide the ultimate solution to:

• Compensate for pipe misalignment
• Absorb compression and extension
• Accommodate pressure loads
• Reduce noise
• Isolate vibration
• Neutralize axial, lateral, angular stresses
• Prolong life of motive equipment
• Prevent damage to pipe-work or ducting system
• Relieve stress of on equipment flanges
• Adjust for seismic movement

Applications of rubber expansion joints

In a relatively short space, rubber expansion joints provide the ultimate solution to:

HVAC Applications

Rubber expansion joints are used in a variety of heating, ventilation, and air conditioning systems, which includes commercial and industrial buildings, hotels, apartments, schools, shopping plazas and aboard ships to relieve stress in ductwork. Rubber expansion joints are installed to isolate equipment like pumps, compressors and chillers from the piping system. A variety of configurations of joints are available accommodating different shapes, service and connection requirements.

Process Piping
Protection of a process piping system is an important use for rubber expansion joints. The joints reduce noise and vibration caused by forces in pumps. They also centrifuges by behaving as a shock absorber in systems handling abrasive slurries, corrosive chemicals, or very reactive liquids or gases. Thermal movement in a piping system can also be avoided by using rubber joints. The excellent chemical resistance of rubber and synthetic elastomers make these joints ideal for process piping systems.

Power Plant Applications
Nuclear and fossil fuel plants use Rubber expansion joints so as to reduce thermal expansion and contraction on condenser lines, condensate lines, steam turbine exhaust lines, aeration systems and cooling water lines. Reliability, large size capability, long life, and the ease with which they accommodate themselves to movements make these expansion joints ideal for power plant applications.

Industrial Ducting Systems
Rubber expansion joints have been installed in demanding industrial ducting systems where there are problems like heavy vibration, dry or wet corrosive materials, flutter etc.

Marine Systems
Eliminating the destructiveness of electrolysis and at the same time insulating against the transmission of sound, rubber expansion joints allow the necessary motion and flexibility in a 'moving' ship's piping system. The compactness, resilience and low stress features of rubber make these joints ideally suited for shipboard piping systems. The rubber joints are popularly used in areas like auxiliary condenser, air intake on diesel engines, overboard discharge line between condenser and hull, ventilation lines, flush and sanitary systems, fire and bilge pumps, to name a few.

Pollution and Wastewater Treatment
Water treatment plants, waster water treatment plants, Sewage treatment plants, and air scrubber systems all employ the use of rubber expansion joints. Due to their resistance to abrasion and corrosion as well as their flexibility feature, rubber expansion joints are ideal to be used in raw and secondary sewage lines, sludge pumps, centrifugal air blowers, scrub stacks.

Want more information on Special Shape Rubber Price? Feel free to contact us.