declare
  -- Local variables here
  i integer;
v_clob    CLOB;
v_varchar VARCHAR2(32767);
v_start   PLS_INTEGER := 1;
v_buffer  PLS_INTEGER := 32767;
blob_in   blob;
x         xmltype;
begin
  -- Test statements here

BEGIN
DBMS_LOB.CREATETEMPORARY(v_clob, TRUE);

select f_blob into blob_in from blob_xml where id = 1;

FOR i IN 1 .. CEIL(DBMS_LOB.GETLENGTH(blob_in) / v_buffer) LOOP

   v_varchar := UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(blob_in,
                                                         v_buffer,
                                                         v_start));

   DBMS_LOB.WRITEAPPEND(v_clob, LENGTH(v_varchar), v_varchar);

   v_start := v_start + v_buffer;
END LOOP;

x := xmltype.createxml(v_clob);
dbms_output.put_line(x.getclobval());

end;

end;
ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00210: expected '<' instead of '?'
Error at line 1
ORA-06512: at "SYS.XMLTYPE", line 5
ORA-06512: at line 29

x := xmltype.createxml('<c>'||v_clob||'</c>');