| Applies To | |||
| Product(s): | AutoPIPE, | ||
| Version(s): | ALL | ||
| Environment: | N/A | ||
| Area: | Hanger Selection | ||
| Original Author: | Bentley Technical Support Group | ||
Problem:
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.
Solution:
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.
See Also
Spring Hanger Selection - AutoPIPE