Session time in asp.net

 If you want to set the timeout to 20 minutes, use something like this:

    <configuration>
      <system.web>
         <sessionState timeout="20"></sessionState>
      </system.web>
    </configuration>

reference:-  https://stackoverflow.com/questions/1205828/how-to-set-session-timeout-in-web-config

https://www.c-sharpcorner.com/blogs/how-to-set-session-timeout-in-asp-net1