Thermal shock to copper pipe

[Excal]

I have recently been involved in a project where a shell and tube heat exchange became damaged.

Three of the copper tubes that carry water through the shell developed pin holes while the shell was being charged with refrigerant( potentially -40C but unlikely to be this low). The manufacturer suggests this damage was caused by the thermal shock of refrigerant charging. Although a specialist pipe freezer who uses nitrogen to freeze pipe to -196C and several other people with more knowledge than me, say that if this was the case the damage would not be pin holes but obviouly bulging and blistered pipe with cracks.

Anyone have any experience ?

 

[arunmrao]

Normally high conductivity copper is used for manufacture of tubes and electrical equipment. One of the steps in manufacture is I think green poling. If this process is not complete pinholes can occur in the tube. If the cause is thermal shocks(very doubtful as copper is a very good conductor),failure mode should be blistering or cracks.

I am not a copper specialist .

 

[EdStainless]

Prior defects from manufacturing or corrosion damage might open up and become leaks after repeated thermal shock, but the thermal cycling of the Cu will not cause any damage on its own.
How were the tubes leak tested before the HX was built? How was the HX tested prior to charging? I have seen large industrial refigeration heat exchangers Helium leak tested prior to service.

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