Hi Abhishek & DB49,
I found the root cause of this duration behavior in APO.There is a functionality called "Flow production" in routing when it is checked,system will consider the longest production duration of the sequence.After removing this check APO created order as per the duration in PDS.
Regarding the Flow production I do not have a much idea about this functionality but SAP has provided only few information about Flow production.
"In flow manufacturing the operations overlap completely. In contrast to overlapping operations, in flow manufacturing all operations that belong to a flow manufactured sequence are extended on the basis of the longest production duration of the sequence."
Thanks a lot for your support.It really helped me in my analysis.
Thanks and regards
Debasis Nanda