Dear Mr. Richards,

I have following query, kindly clarify the reason.

L1 W+T1+P OPE
L2 W+T2+P OPE
L3 W+T3+P OPE
L4 W+P SUS
L5 L1-L4 EXP
L6 L2-L4 EXP
L7 L3-L4 EXP
L8 L1-L3 EXP (EXP. STRESS RANGE)

& WHY NOT

L8 L5-L7 EXP

Amit,

The expansion case is a combination case that results from subtracting the sustained case from the operating case. As such the expansion case represents the change in the piping system due to the effect of temperature, but in the presence of other loads. This is important because
the restraint status of the operating and sustained cases can be different if there are nonlinear restraints (such as +Y, -Z, any restraint with a gap, etc.) or boundary conditions (friction).

hence we should consider L8 as L1 - L3 inorder to get expansion values in presence of other loads.

Regards

You wouldn't want to create range from an earlier range (L5-L7), that doesn't make sense. However, in addition to L1-L3, you may also need L1-L2 and L2-L3. The necessity of these cases depends on what load magnitudes actually make up L1, L2, and L3. The objective is to encompass the extreme displacement stress range.