this should be a simple task. But I couldn't find straightforward answer in Google. How to take backup of SSIS packages from database instance just as like normal database backup is taken, and how to restore it in different database instance.
You can connect to the Integration Services instance, right-click the package you want to move to another server, and select "Export package...". Change the "Protection level" for the package to "Do not save sensitive data with user key".
Then on the destination Integration Services instance, right-click the MSDB folder and select "Import Package..." and change the Protection level, if necessary.
Differences between package-level protection can be researched here: http://sqlblog.com/blogs/eric_johnson/archive/2010/01/12/understanding-the-ssis-package-protection-level.aspx
If you want to backup and restore an entire SSIS Catalog, detailed steps can be found here: https://msdn.microsoft.com/en-us/library/hh213291(v=sql.110).aspx