Problem with using MEMO BLOB fields when creating a new record in INTERBASE

Is it possible to create a new record within Interbase SQL (using the
INSERT statement) and specify BLOB data eg

INSERT into tTest (fCustomerNo,fOrderNo,fOrderDesc)
VALUES ('0001','0004','This is the string that will be copied to the blob
field fOrderDesc')

I'm currently getting 'conversion error from string'  when trying to do
this.  Is there anyway of passing a blob or string parameter and using this
value (for a blob field) in an INSERT statement when creating a new record
?  I'm having to do this as the memo fields are mandatory when adding a new
record in our Delphi application.

Thanks very much,

Stef Fiorentini