Considering Day from 6 A.M to 6 A.M

Dear All ,

    I am working in implementation project . This project is related to GAS & Energy . For some calculation purpose I have to consider day from

     6 A.M to 6 A.M I searched for function module to achieve this but I am unable to get . Will any body Please suggest how can we achieve this in

     ABAP program . Thanks in advance .

Thanks,

Santhosh.v