Hi Ndiankou,
Thanks for your findings. Actually, the attached message is not related with the modified part number and new added Description column of elbow in Tube & Pipe run. Message still pops up, If you create one style applied the standard ASME 16.22 90deg C x C 1 and ASME B10.36 Pipe with threaded End in tube & pipe. This is Inventor 11 Tube& Pipe logic, which makes mismatched endtreatment of pipe and elbow can not be created.
In Inventor 2008 & 2009, there is function enhancement in Tube&Pipe Style dialog. When you create and save that kind of style, a dialog will prompts "End treatment does not match. Do you wish to continue?" Thus, you could select Yes to continue, or No to stop.
Hope it helps.
Thanks,
Ruth(Autodesk)