How do I Add Integration Services to existing SQL Server 2012 Install that has no internet access
You have to create an administrative install point:
SSDTSetup.exe /layout &lt;destination&gt; 
then copy the files to your isolated instance.
Check out https://blogs.msdn.microsoft.com/ssdt/2014/07/23/creating-an-administrative-install-of-ssdt-update-for-visual-studio-2013/ for details.