Many schemes for calculating Factored Diameter Inches (FDI) make use of the ratio (Nominal Wall)/(Standard Wall). SpoolFab ships with a weld wall factor table that is populated with zeroes as shown below, so that the wall has no effect on the FDI calculation.
The weld wall factors are stored in SFClients\Data\Master\WWMaster.ac2.
An alternative version of WWMaster.ac2 that is populated with NominalWall divided by Standard Wall for most commonly used sizes and walls is available as a compressed folder, WWMaster Wall divided by StdWall.zip. Some of the entries in that file are shown below.
To switch to the alternative weld wall factors, unzip the compressed folder and copy WWMaster.ac2 into the relevant folder, replacing the existing file of the same name. This will generally be SFClients\Data\Master. Sometimes client folders have their own dedicated Data folder, so you may need to copy into that instead.