Different Rubber Expansion Joint types.
Rubber expansion joints are also called rubber bellows/flexible connectors. These are found in HVAC/Plumbing systems and industrial applications. Typical rubber expansion joints are:
Single sphere
Single sphere expansion joints have one round body made of rubber or other elastomeric materials. The single sphere expansion joints can be lateral or angular but have limited axial compression and extensions capability. Apart from single sphere expansion joints these are the smallest and cheapest.
Double sphere
Inside the connector are double sphere expansion elbows which connect two spheres with reinforced rubber adequately. A dual sphere expansion elbow ensures normal lateral and angular motion along with increased axial compression and extension. Most of the high pressure systems and systems with great thermal expansion and constriction use the double sphere rubber expansion joint.
Tied universal
The tied universal expansion joint has a sphere middle body having a second pair of reinforced rubber and identically tightened tierods. Because of this design the tied universal type of expansion joint reduces in Vienna in all three directions.
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Material options
The materials from which rubber expansion joints can be manufactured have different properties and each have their own sphere of application which is productive, for example:
Ethylene propylene dine monomer above average temperature, ozone and weather resisting EPDMs are found in high temperature, outdoor applications.
Neoprene. Smoking good resistance to low cost, oils and chemicals and moderate temperature resistances, Neoprene – rubber expansion joist widely applied in construction and vehicle manufacturing industry.
Specialty Joints
Besides standard rubber expansion joints there are also special expansion joints conditioned for particular applications:
Applications
Most applications require rubber expansion joints. It can be used in.
Such wide application of rubber expansion joints relieve stress and vibration, move the elements of piping system farther apart to obtain safe length for expansion and contraction of piping, dampen the shock of discharge, loading or pressure relief.
The rubber expansion joints can work with any part of system using different materials and design, that is why the expansion joint is so popular.
The Right Expansion Joint – How to Choose?
Suitable choice rests largely on the case conditions and requirements for the piping system. Thus a proper rubber expansion joint should have some rules of application in one way or another. There are some and Relationship between Relative size and adjacent pipe equipment.
Remember that if they are installed incorrectly, the rubber expansion joint will not work properly and may fail, lose tightness or suffer some other mishap.
Hence misalignment causes uneven stress distribution and fast wear resulting in premature failure of your piping system. Follow the manufacturer’s guidelines therefore when selecting and aligning your rubber expansion joint.
Codes and Standards
So rubber expansion joints should be designed, selected and installed according to some industry codes and standards. The following are some of probably the most familiar standards:
EJMA – Expanded Joint Manufacture Association: This body establishes design, manufacture and test norms for expansion joints.
ASME Americas Society of Mechanical Engineers: Asme b 31 codes specify the expansion joints to be used in piping systems.
Conformity with these standards ensures the long life of rubber expansion joint and makes your piping system safe and hazard free.
Top Manufacturers
A rubber expansion joint can not go stronger than its weakest point. Make sure to buy from a legitimate manufacturer and work with only reputable suppliers. Finally consider the time, cost and ease of manufacture: get quotes from some suppliers and watch lead times. Please help me with other sections above.
Preparation:
Continuing from here, once the expansion joint installation is complete, the piping system should now be properly aligned, anchored and supported. Installation will go smoothly because it can go through alignment on both ends.
Handling and Storage
Alignment and Positioning: An expansion joint should be placed precisely in a given piping project. Several factors have to be considered during the installation like gap size between flanges at each end and torque of bolts.
Correct installation and positioning can improve the performance and extend the service life of rubber expansion joints. Anchoring and guiding are necessary as well as insulation. Manufacturers outline best practices for installation which must be followed precisely to achieve the best affect and reliability. Using the rubber expansion joints correctly anchored and guided they will be moving in the expected more and within the allowed capacity without excessive stress or misalignment. Anchoring means restraining the piping system mvoement and transfer of required loads to the support structure. The job of guiding, however, is to control the movements and the range of the effect.
The isolation may be necessary in some cases when the rubber expansion joints will experience excessive head or alternatively cold. Further insulation may be needed for temperature control in the piping system and for better energy use. Insulation installation should be carried out according to the manufacturer’s gyrolein, including material type and application technique. Insulation may also prevent earlier wear of joints, extending service life several times.
Visual Inspection: In this case I would check the rubber bellows at the expansion joint. I would check them for damage – cracks, cuts abrasions or excessive wear – and then replace them if they were damaged. I would also look for leakage signs and bellows deformations. Assess whether the joint can move over the designed range of spatial movement with the rubber in proper condition without obstruction or binding.
Routine inspection of rubber expansion joint is the best maintenance in this case. As per manufacturer and engineering practice recommendations, you have two ways to do so:
Anchoring and guiding inspection: Make sure that the guides and anchors to which the joint is subjected are in good order and working properly.
Environmental factors: Sometimes external influences cause premature wear out. This includes degenerations due to high temperatures, aggressive chemicals, UV radiation or many others.
Document the inspection and keep exact records so you have something to refer to later.
Defects & Issues of Exploitation.
The other most important maintenance task is finding out possible defects and issues. Common ones are:
* Surface cracks or crazing: It may indicate material degeneration or unacceptable stress of the rubber bellows, respectively.
* Deformation/permanent set: This can indicate excessive movement or a bad installation.
* Leakage: Leakage of vital substance like steam from the bellow should not be allowed.
* Poor alignment/anchorage.
Once you found something in that list above, you should act to remove it or contact the manufacturer.
After such preliminary work has been done, testing or cleaning processes should be considered in cases where:
the application or other operating conditions may require such action periodically.
The analysis of existing data demands it.
Testing might include pressure or leak testing and other nondestructive testing. Such a move could cut your haircut on the state of the whole joint. Cleaning involves removing debris and foreign contaminants from the expansion joint surface. Here the manufacturer guidelines are very important. Those ways and means which are dangerous for the rubber material are developed during cleaning.
Several failure modes exist for rubber expansion joints. The first is excessive movement. When the expansion joint is moved more than designed, rubber deforms and metal parts are stressed to high stresses. The expansion joint fails, therefore. Material degradation is among the disadvantages of excessive exposure of material to environmental factors or to the chemical fluid stored in the pipe system. These include ultraviolet exposure, high temperature and general aging. The failure mode associated with the fatigue of the rubber expansion joint is represented by the repetitive extension and contraction of the bellows. The bellows cracks or tears when the numbers of the cycles are enough. Some fail because of improper installation or the wrong installation. They include poor sizing of joint, improper anchoring/bending and flange offset.
Mechanical Overloading
Frequent excessive or poorly distributed loads can overload the rubber bellows and produce high stresses and strains in the material. Mechanical overloading could happen with pressure surges, sudden changes in flow rates or even moving heavy equipment near the piping system. Mechanical overloading causes overstretching, delamination or complete failure of the bellows.
External Damage
Physical damage due to impact, abrasion or other external influences may compromise the rubber bellows integrity and cause premature failure.
Root Cause Analysis
Failure of an expansion joint requires a root cause analysis to determine the cause. Root cause analysis may include:
Review installation and maintenance records.
Examining the failed joint for indications of failure mode.
Investigation of operation conditions as well as system parameters.
Evaluation of piping system layout and design.
Identifying the root cause allows appropriate corrective actions and future recurrence of failures.
Troubleshooting Guidance
Manufacturer’s recommendations & industry best practices may provide useful troubleshooting information for specific rubber expansion joints problems. Common troubleshooting steps are:
Change of anchors or guides position to realign joint.
Wearing or damaged parts are replaced.
System layout/support structure is reconfigured.
Upgrade to another kind of or material of expansion joint suitable for the conditions.
Sometimes you will have to contact the manufacturer or maybe another competent specialist for more troubleshooting help.
When to Replace
Long lasting rubber expansion joints will eventually need to be replaced. The reasons for replacement could be:
-Unrepairable wear or damage
-Material beyond acceptable deterioration levels.
-Conditions beyond the design capabilities of the joint.
-Exceeding manufacturer’s recommended service life or cycle count.
Replacement on time avoids catastrophic failures, ensures safe operation of the piping system and reduces downtime and associated costs.
Be aware of common failure modes, perform root cause analysis, follow correct troubleshooting procedures and be proactive when replacing rubber expansion joints in your piping system.
