Even if you could get into the A1 pier, you'd be nuts to do so
when flying out of B3. A1 security isn't bad, but I've found
the exit procedure at B3 to be ugly, stressful, and long in
the evening.

Anyhow, you're entitled only to use the business lounge at
gate 60: it's okay, in a sort of late 20th century way,
with decent little sandwiches and wines that UA wouldn't
be proud to serve (but they're free).