Thank you Ujwol & Sung Hoon Kim for your reply. Please find the details below
1. We haven't enabled Max Session Timeout
2. We have enabled IdleTimeout only and we have set DisableSessionVars ACO parameter to "No"
3. The value I am getting from HTTP_SM_TIMETOEXPIRE is something like this "664593296"
Query :1. I have converted this number to minutes and I don't think it is in minutes format or I am missing something here.
I need to know the time in minutes by when the session is going to expire, so that I can take some action in UI accordingly.
Thank you for your help.