Pipes and their contents behave differently from what one would expect by looking at the thermal conductivity of the material of the pipe.
Example: One 10kg package of crude oil 100°K hotter than the pipe through a pipe segment of a certain material 10 times.
Pipe out of insulation recieves 56840DTU
Pipe out of sandstone recieves 133280DTU (~2.3 times)
However their thermal conductivity is vastly different 0.000... vs 2.9 (Crude oil having 2)
Steps to Reproduce
Load file, unpause
This issue has not been confirmed by a developer yet.