Expansion joints (compensators) in thermal systems are key components to absorb the displacement of piping systems due to thermal expansion and contraction, and prevent pipes and equipment from being damaged by stress. Damage to expansion joints can originate from a variety of reasons. Here are some common damage causes analyzed:
Temperature and pressure fluctuations：
Extreme temperature changes or pressure fluctuations can lead to fatigue of the bellows material of the expansion joint, which may lead to cracks and leakage under long-term action.
Excessive temperatures may also lead to changes in the physical properties of the bellows material, such as creep, which affects its elasticity.
Medium corrosion：
The conveyed media may be corrosive, especially those containing acids, bases, salts, or solvents, which can cause chemical attack on the expansion joint material.
Corrosion may weaken the strength of the material, resulting in thinning of the bellows wall thickness and eventually leakage.
Ice blockage：
In a refrigeration system, if there is too much water in the refrigerant, when the temperature drops below zero degrees, ice plugs will form at the expansion joint throttle, hindering the flow of the refrigerant.
Mechanical injury：
During transportation, installation, or maintenance, expansion joints may suffer impacts, scratches, or depressions that compromise their structural integrity.
Improper installation, such as improper pre-stretching or pre-compression, can also cause bellows to deform or damage.
Internal blockage：
Slag, oxide scale, or other impurities may enter the expansion joint in the fluid flow, causing clogging, affecting its ability to normally displace.
excessive displacement：
If the actual displacement of the expansion joint exceeds the maximum amount of displacement allowed by the design, the bellows may be damaged by excessive stretching or compression.
Design or selection error：
Using mismatched expansion joint types or specifications, such as undersized or oversized, may not effectively absorb pipe displacement, resulting in damage to the expansion joint or piping system.
Power component failure：
For thermal expansion valves, leakage or failure of their power components can cause the valve to close, interrupting the flow of refrigerant.
Dust and dirt：
Dust accumulation inside non-metallic expansion joints may cause the expansion joint skin to burst, especially in the bottom area.
Aging and Wear：
Aging and wear of the material over time can also reduce the performance and longevity of the expansion joint.
To avoid the above problems, the expansion joints of the thermal system should be inspected and maintained regularly to ensure that they operate under suitable working conditions and to replace worn or damaged parts in time. In addition, in the design and selection, the working conditions should be fully considered, and suitable materials and structures should be selected to prolong the service life of the expansion joint.