In the Hue safety valve:

[desktop]
[[session]]
ttl=900


http://gethue.com/how-to-configure-hue-in-your-hadoop-cluster/

*Note:* To override a value in Cloudera Manager, you need to enter verbatim
each mini section from below into the Hue Safety Valve
:
Hue Service → Configuration → Service-Wide → Advanced → Hue Service
Advanced Configuration Snippet (Safety Valve) for hue_safety_valve.ini

Romain