How hot is hot enough to consider how thermal growth may affect machine alignment? That is a trick question, because there is more to consider than just delta t. What is the casing material and what is that coefficient of expansion? Also what is the height of the shaft? When you consider these three questions then you are able to account for thermal expansion differences that may occur between the machines and maybe “precisely misalign” the two machines so that they grow into alignment under normal operating conditions! https://kvgo.com/Example/Thermal-Growth