Confirm what Autopipe uses for calculating the following on ASME NB elbows: Flexibility, Stiffness Section Modulus Stress Indices Pressure Stiffness, Does it use the Elbow input properties (eg OD and thickness) or the preceding pipe properties?
ASME NB-3683.7 states that the indices should be calculated from the mean pipe radius.
An AutoPIPE model is comprised of elements added together to form a segment. Each element is made of a set of connected node points (ex. A02-A03). Each element has defined pipe properties (see Press/Temp/PipeID tab on the input grids, PipeID per element pairs), applied loads, etc. applied to them. To answer your question on which side of the of the node point are the properties used to perform analysis calculations for an elbow the answer is the elbow element N+ to F- pipe properties are used.
See the Stress indices report and Pre-verification report, notice that both of these reports have both +ve and -ve side of a node points listed. The analysis is conducted with the respective properties and loads.
"Code Compliance" sub-report using Results> Output Report
Bentley AutoPIPE