declare 
out_xml clob;
l_buffer RAW(20000); 
l_text_buffer VARCHAR2(32767); 
nOffset number := 1;
iMaxSize integer := 32767;
iclobSize integer;
vBuffer varchar2(32767);
begin 
		
select a.RTF_FILE_DATA into out_xml from erat_report_rev_details a where rownum<2;

iclobSize := dbms_lob.getlength(out_xml);
dbms_lob.read(out_xml, iMaxSize, nOffset, vBuffer);
dbms_output.put_line(iclobSize||vBuffer);
end;