Hi Ganesan.
When did you query PSAPTEMP? Was it checked while that partical process/SAP Job was running?
PSAPTEMP is used to store data while sorting,grouping,etc. if PGA is not sufficient. It is quite normal to get ORA-01652 while a long running operation is performing a huge sort operation.
As a rule, PSAPTEMP should be 2-2,5 time bigger then the biggest index in the database.
Regards,
János