The number of MINUTES after which a web app times out is defined in the web.xml this way.
The WebLogic Server waits TimeoutSecs (in SECONDS) before timing out a session as shown below: The default value, if not specified, is 3600 secs.
When timeout is set in both the deployment descriptors, the web.xml entry OVERRIDES the one defined in the weblogic.xml. This preference can be changed by a special value.
This will let the app use the TimeoutSecs defined in the weblogic.xml for session time out. There is yet another special value -1, in which case the session never times out. Of course, the weblogic entry is overriden in this case too.