Dear Omdo,

T1>T2>T3>T4....>T ambient?
I think those are complete load case set up. L42 performed to have "full expansion stress range" while L40 to have the higer expansioan stress and L41 the minimum expansion stress.

L40, L41, and L 42 are not too neccesary if all T1,T2,T3, and T4>T ambient.

The lowest temperature may cause the higher expansion stress let say if T1=80, T2=60, T3=40, T4=-80, Tambient=19 deg C.