I thought I fully understood the difference between using the hot load procedure (HLP) and the cold load procedure (CLP) to size a spring hanger, but I guess I was wrong. I have tried running the "WALKTHRU" sample using both the HLP & the CLP, which should give me the same spring size, given the same thermal deflection and GR load from my V-stop run. I end up with two different spring sizes, which has to be incorrect.
No, each procedure is fundamentally different when sizing a spring and therefore the spring size and cold load will be different.
As mentioned in the online help:
A. Hot Load Design Hanger Selection Procedure:
A rigid restraint (V-stop) replaces the hanger for the gravity (GR) load case. The calculated support reaction is the hot load to be carried by the hanger.
B. Cold Load Design Hanger Selection Procedure
A rigid restraint (V-stop) replaces the hanger for the gravity (GR) load case. The calculated support reaction is the cold load to be carried by the hanger.
Example: GR load on the support Dy = -1975 lbs, and T1 movement, Dy = +0.204".
Per the Cold Load method, the Hot Load is interpolated to be 1836.6 lbs as shown below:
Per the Hot Load method, the Cold Load is interpolated to be 2158.2 lbs as shown below:
Note: In the cold load procedure above the Cold Preload for all springs was 1975.0 lbs, however here in the Hot Load procedure, all the Hot load values are 1975.0 lbs.
Again, totally different springs are selected when using the different hanger selection procedures.
Spring Hanger Selection - AutoPIPE