{HEAD ~ Multi stage process} for demetalation, {TAIL ~ desulfurization} and dewaxing of petroleum oils 
for
{ HEAD ~ Multi stage process } for demetalation , { TAIL ~ desulfurization } and dewaxing of petroleum oils
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH