UA 2 then UA 3912 at San Francisco
Singapore → San Francisco → Houston
Timetable, San Francisco time
09:15UA 2 from Singapore at the gate
23:00UA 3912 to Houston leaves the gate
13 h 45 apart on the timetable
UA 3912 leaves 13 h 45 after UA 2 arrives on the timetable: more than half a day, so not a connection we count.