Expansion Joints: Common Causes of Failure
A correctly dimensioned and correctly installed expansion joint should not require any special maintenance other than inspections carried out to assess other parts of the pipe system in which the expansion joint is installed.
However, there are instances when expansion joints can fail. Knowing the common causes of damage and faults in expansion joints can help you avoid them. Damage can occur during shipping and handling, during installation or during operation. Here are a list of some of the faults to try and avoid.
Shipping and handling damage
- Knock-damage, dents, scuffs and scratching of the bellows caused by incorrect handling or inflicted after installation.
- Unanticipated detrimental influences from the environment such as corrosion caused by salt, chemicals or the like in the atmosphere.
Installation damage and installation errors
Incorrect location – installing expansion joints at a position in the pipework not intended by the system designer.
- Using the expansion joint to correct fabrication errors without first confirming this is acceptable with the designer
Premature removal of shipping or pre-tensioning devices or failure to remove them after installation.
Damage from weld spatter due to lack of protection during installation.
Installation of units fitted with flow liners with the liner against the flow direction.
Corrosion damage caused by the medium, in particular due to chloride presence.
- Fatigue failure due to unforeseen vibration in the system.
- Fatigue failure caused by movements for which the expansion joint was not designed, especially lateral movements.
- Damage caused by accumulation and packing of foreign material between the bellows convolutions, which can affect the bellows internally or externally.
Avoiding the above common causes of damage that may occur during transit, installation and operations can help to reduce the risk of expansion joint failure. Taking a proactive approach to avoid these can lead to a longer service life for expansion joints.
Performing regular inspections can significantly reduce the risk of expansion joint failure, however they do not totally guarantee that damage has not already begun or will not inevitably occur.
KLINGER recommends that you carry out ongoing inspections of the pipe system throughout its service life.
The aim of these inspections is to check for the presence of rust or whether parts have come loose, etc. Frequency of these inspections is determined on an individual basis based on the function of the system, occurring loads and so on.
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