Time out settings for Users in OBIEE 10g and 11g

10g:

For Time to Expire for Idle Connections

add the below code in instanceconfig.xml

To set time to expire for Idle Oracle BI Presentation services Client connections.
<ConnectionExpireMinutes>enter no of minutes</ConnectionExpireMinutes>

Setting the Time to Expire for Oracle BI Presentation Services Client Sessions
<ClientSessionExpireMinutes>enter no of minutes</ClientSessionExpireMinutes>

11g:

This functionality in 11g can be acheived from Enterprise Manager.