I am not understanding this.
Propane does not freeze anywhere near -60C. Wikipedia [1] says it freezes (liquid to solid) below -187C and boils (liquid to gas) above -42C.
Propane is probably unusable as a fuel below -42C because there is no vapor leaving the tank [not within my experience]. That is different from the propane being a solid.
[1] https://en.wikipedia.org/wiki/Propane Melting point −187.7 °C Boiling point −42.25 to −42.04 °C
I don’t know that it turns to a solid, but it very much doesn’t work past -35C.
Ask anyone that lives in Yukon/Alaska. They’ll tell you.
It freezes as pressure drops when you try to use it from the tank. Like how a can of air duster gets cold when you spray it.