You can work with project files while you are disconnected from Vault.
If you are not connected to the network, in general, you can work with your local copies of project drawings the way you normally do. However, you cannot perform project management functions (such as checking in and checking out files), you cannot get updated versions of any project files, and you cannot create new references to project objects while you are disconnected.
Before you disconnect, you should update your local copies of any project files by getting the latest versions of any project files that you are working with, including the source drawings for any project objects that your drawing references.