I used Oracle Workflow for a couple of years from 2002. The icons it ships with are pretty terrible so I redesigned my own.
I never quite finished the full set of icons but concentrated on the ones we used often. I also produced some 16x16 versions for the executable (yes - I resource edited mine!). I also added a manifest file to my source directory to allow XP and later versions of Windows to style the toolbar, buttons etc.
Since Oracle Worflow of now EOL I doubt there are many people using it now. These images will work fine with other workflows and other applications too. Anywhere that uses visuals for flow. The icons are mainly 32x32 in png format.
These icons are licensed under a Creative Commons Attribution 3.0 license.
If you can't or don't want to provide a link back, please contact me for licensing details.