To take backup of lob in oracle export, first, you need
and install DBBlobEditor.
Run DBBlobEditor.
To take backup of lob in oracle export, click ‘Tools->Export LOB’, LOB export form is displayed, you can export lob data from a table:

or a query:

And you can restore your LOB data, click ‘Tools->Import LOB’, LOB import form is displayed:

DBBlobEditor is a database tool that helps DBA and Database Programmer edit Oracle LOB (BLOB, CLOB) data directly.