Appendix SiEN34-705
200 General Information
7.14.6 Example 6: Cracks Develop in Field Pipes due to Thermal Expansion
and Contraction
Situation Refrigerant piping has developed cracks in soldered points and is leaking gas.
Cause Both ends of the pipe have been tightly fixed in place.
↓
Starting and stopping the compressor has caused temperature to vary, thus the pipes have
expanded and contracted which places stress on soldered parts.
↓
Cracks have formed because of repeated expansion and contraction.
Remedial Action Fit the pipe with a loop as shown in the below drawing.
Main Points ! Take thermal expansion and contraction along the spline into consideration when installing
pipe supports.
For Your
Reference
Expansion (m) = Full length × Coefficient of thermal expansion × Rise in temperature
Coefficient of thermal expansion for copper: 16.5 × 10
-6
Example For a pipe length of 10 m and a rise in temperature of 50°C, expansion reaches
8.2 mm.
Before remedial action
After remedial action
Tightly fixed
Tightly fixed
Cracks developed here
in soldered parts
Absorb expansion
with loop.
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