Hello friends,

I'm trying to quantify the effects of temperature changes on process piping and I would appreciate some feedback.

I have a simple 1-1/2'' sanitary line that goes from a flow panel in a building to another in a second building, passing outside in the process. The two points are approximately 50 m appart and the routing goes from floor level to approximately 5 m in height to connect both buildings. Here's a view of the layout :



I wanted to evaluate the impacts of the temperature change of having an empty outdoor routing exposed to -40C suddenly filled with hot CIP solution. In reality, the outdoor portion will be insulated and heat traced to avoid freezing but I want to study the worst-case scenario below.

The indoor extremities are at a pleasant 20C while the middle outdoor portion is at -40C. I'm using TEMPERATURE 1 for this varying ambient temperature along the piping.

TEMPERATURE 2 is my design temperature, which I set to a ceiling value of 100C. This temperature is applied for all the routing.

My load cases are the following (besides alt sus):
L1 (HYDRO) : WW + HP
L2 (OPE1) : W + T1 + P1
L4 (OPE2) : W + T2 + P1
L6 (SUS) : W + P1
L7 (EXP1) : L2 - L6
L8 (EXP2) : L4 - L6

CAESAR II is however recommending me another load case :
L9 (EXP3) : L2 - L4

My plan was to look at OPE1, OPE2, EXP1 and EXP2 to have an idea of the flexibility and associated stress of both temperatures sets.

I have some doubts understanding what EXP3 represents exactly. It seems to be a what I'm looking for as it calculates the displacement stress range between T1 and T2, which is a wider delta than T2 with the default CAESAR II ambient.

As I suspected, the preliminary results seem to indicate this. The L9 case is more critical than L8 by a small margin. I think it should be a representation of the expansion stress between the two temperatures states.

Is my reasoning correct ?
Is there another approach I should look into ?

Thanks for the feedback