Hi - I wasn't able to open your SLDPRT file for some reason - probably because I'm using SW 2013 and yours is probably more advanced.
If so, please save it as a STEP file (File>Save As>*.STP,*STEP.), and re-post it.
Is the bulkhead exactly circular? Maybe you could do so a simple work-around by producing it using a single "Revolved Boss" or "Swept Boss" feature?
One way or another, please describe exactly what problem you encountered.