SQL> drop table my_clob_table;

Table dropped.

SQL> create table my_clob_table(ID number,MY_CLOB clob);

Table created.

SQL> declare
  2  qryCtx dbms_xmlgen.ctxHandle; 
  3  result clob;
  4  savCtx DBMS_XMLSTORE.ctxType;
  5  n number;
  6  begin
  7   result:='
  8          <ROWSET>
  9           <ROW>
 10            <ID>123</ID>
 11            <MY_CLOB>'||LPAD('F',32000,'F')||'</MY_CLOB>
 12           </ROW>
 13          </ROWSET>';
 14   savCtx := DBMS_XMLSTORE.newContext('my_clob_table');
 15   DBMS_XMLSTORE.clearUpdateColumnList(savCtx); 
 16   DBMS_XMLSTORE.SetUpdateColumn (savCtx, 'ID');
 17   DBMS_XMLSTORE.SetUpdateColumn (savCtx, 'MY_CLOB');
 18   n:=DBMS_XMLSTORE.insertxml(savCtx,result);
 19   DBMS_XMLSTORE.closeContext(savCtx);
 20  end;
 21  /

PL/SQL procedure successfully completed.

SQL> drop table my_blob_table;

Table dropped.

SQL> create table my_blob_table(ID number,MY_BLOB blob);

Table created.

SQL> declare
  2  qryCtx dbms_xmlgen.ctxHandle; 
  3  result clob;
  4  savCtx DBMS_XMLSTORE.ctxType;
  5  n number;
  6  begin
  7   result:='
  8          <ROWSET>
  9           <ROW>
 10            <ID>123</ID>
 11            <MY_BLOB>'||LPAD('F',32000,'F')||'</MY_BLOB>
 12           </ROW>
 13          </ROWSET>';
 14   savCtx := DBMS_XMLSTORE.newContext('my_blob_table');
 15   DBMS_XMLSTORE.clearUpdateColumnList(savCtx); 
 16   DBMS_XMLSTORE.SetUpdateColumn (savCtx, 'ID');
 17   DBMS_XMLSTORE.SetUpdateColumn (savCtx, 'MY_BLOB');
 18   n:=DBMS_XMLSTORE.insertxml(savCtx,result);
 19   DBMS_XMLSTORE.closeContext(savCtx);
 20  end;
 21  /
declare
*
ERROR at line 1:
ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00222: error received from SAX callback function
ORA-06512: at "SYS.DBMS_XMLSTORE", line 78
ORA-06512: at line 18

SQL> insert into my_blob_table values ( 123, 'xxx');
insert into my_blob_table values ( 123, 'xxx')
                                        *
ERROR at line 1:
ORA-01465: invalid hex number

SQL> insert into my_blob_table values ( 123, 'FFF');
     PL/SQL procedure successfully completed.

SQL> drop table my_blob_table;

Table dropped.

SQL> create table my_blob_table(ID number,MY_BLOB blob);

Table created.

SQL> declare
  2  qryCtx dbms_xmlgen.ctxHandle; 
  3  result clob;
  4  savCtx DBMS_XMLSTORE.ctxType;
  5  n number;
  6  begin
  7   result:='
  8          <ROWSET>
  9           <ROW>
 10            <ID>123</ID>
 11            <MY_BLOB>'||LPAD('F',4000,'F')||'</MY_BLOB>
 12           </ROW>
 13          </ROWSET>';
 14   savCtx := DBMS_XMLSTORE.newContext('my_blob_table');
 15   DBMS_XMLSTORE.clearUpdateColumnList(savCtx); 
 16   DBMS_XMLSTORE.SetUpdateColumn (savCtx, 'ID');
 17   DBMS_XMLSTORE.SetUpdateColumn (savCtx, 'MY_BLOB');
 18   n:=DBMS_XMLSTORE.insertxml(savCtx,result);
 19   DBMS_XMLSTORE.closeContext(savCtx);
 20  end;
 21  /
    PL/SQL procedure successfully completed.