create temp table tp01 ( c1 int);
insert into tp01 values (610);
insert into tp01 values (10);
insert into tp01 values (270);

select cast (c1 units minute as interval hour to minute)  as a
      , to_date("00:00","%H:%M") + cast (c1 units minute as interval hour to minute) as b
      ,to_char ( to_date("00:00","%H:%M") + cast (c1 units minute as interval hour to minute) ,"%H:%M") as c
from tp01;

a   10:10
b  2009-09-08 10:10:00.00000
c  10:10

a    0:10
b  2009-09-08 00:10:00.00000
c  00:10

a    4:30
b  2009-09-08 04:30:00.00000
c  04:30