CG-47

                 CG 47 CLASS ADVISORY NR 06-93A1                                

                                                                                

   INTERIM FLUSHING PROCEDURES FOR PRAIRIE AND MASKER AIR COOLERS               

                                                                                

 REF/A/RMG/AEGIS PROG MGR/051143ZMAY93//                                        

                                                                                

 REF/B/RMG/USS PRINCETON/091855ZJUN93//                                         

                                                                                

 NARR/REF A IS CG 47 CLASS ADVISORY 06-93.  REF B IS REPORT OF                  

 CONTAMINATION OF FRESH WATER SYSTEM WHEN FLUSHING PRAIRIE AIR                  

 COOLER.//                                                                      

                                                                                

 RMKS/1.  THIS CLASS ADVISORY AMENDMENT PROVIDES CLARIFICATION OF               

 REF A INTERIM FRESH WATER FLUSHING PROCEDURES FOR THE PRAIRIE AND              

 MASKER AIR COOLERS AS A RESULT OF CONTAMINATION OF FRESH WATER                 

 SYSTEM REPORTED BY REF B.  BUTTERFLY VALVE LEAKBY IS A KNOWN                   

 PROBLEM ON CG 47 CLASS SHIPS.  THEREFORE, SPECIFIC GUIDANCE FOR                

 SHIPS WITH SEVERE BUTTERFLY VALVE LEAKBY IS ALSO PROVIDED.                     

                                                                                

 2.  CONTAMINATION REPORTED BY REF B WAS CAUSED BY HARD PIPING A                

 HOSE FROM A DEEP SINK TO A GAUGE LINE AFT OF THE PRAIRIE AIR                   

 COOLER SEA WATER INLET VALVE.  EXCESSIVE LEAKBY OF BUTTERFLY                   

 ISOLATION VALVES THEN RESULTED IN SEAWATER BEING FORCED INTO THE               

 FRESH WATER ATTACHMENT TO THE HOT WATER LINE.  THE INTENT OF REF               

 A PARA 3.A.(1) WAS TO FILL THE COOLER THROUGH THE VENT PLUG HOLE               

 WITHOUT HARD PIPE ATTACHMENT.                                                  

                                                                                

 3.  THE FOLLOWING GUIDANCE PROVIDES CLARIFICATION OF FLUSHING                  

 PROCEDURES IN REF A PARA 3.A.(1) FOR SHIPS NOT EQUIPPED WITH                   

 COOLERS MODIFIED WITH FILL/DRAIN VALVES:                                       

                                                                                

                                                                                

      A.  USE A HOSE TO FILL COOLER THROUGH THE VENT PLUG HOLE                  

 WITH FRESH WATER UNTIL WATER APPEARS AT THE VENT.                              

                                                                                

      B.  DO NOT HARD PIPE THE FRESH WATER HOSE TO THE COOLER.                  

 SALT WATER CONTAMINATION OF THE POTABLE WATER SYSTEM MAY RESULT.               

  ENSURE AN AIR GAP EXISTS BETWEEN COOLER VENT PLUG HOLE AND FRESH              

 WATER HOSE TO PREVENT POTABLE WATER SYSTEM CONTAMINATION.                      

                                                                                

      C.  BUTTERFLY VALVE LEAKBY IS POSSIBLE.  IF COOLER ISOLATION              

 VALVE LEAKBY IS GREAT ENOUGH TO PREVENT DRAINING OF THE COOLER,                

 REINSTALL VENT/DRAIN PLUGS AND PERFORM SALT WATER LAY-UP IAW REF               

 A PARA 3.A.(2).  FRESH WATER LAY-UP IS THE PREFERRED METHOD EVEN               

 IF THERE IS MINOR VALVE LEAKBY.  ALTHOUGH NOT AS EFFECTIVE AS A                

 FRESH WATER LAY-UP, THE SALT WATER LAY-UP WILL REDUCE THE AMOUNT               

 OF CORROSION DAMAGE OCCURRING TO THE COOLER.                                   

                                                                                

 4.  ECP 47-4811 IS BEING DEVELOPED WHICH WILL INSTALL ADDITIONAL               

 ISOLATION (BALL OR GLOBE) VALVES, VENTS, DRAINS AND FILL                       

 CONNECTIONS TO 33 SEAWATER COOLERS, INCLUDING THE PRAIRIE AND                  

 MASKER COOLERS. THIS WILL ALLOW SHIPS TO EFFECTIVELY ISOLATE THE               

 COOLERS FOR PREVENTIVE AND CORRECTIVE MAINTENANCE.  THE ECP WAS                

 APPROVED AT THE JUN 93 TECHNICAL SCOPE REVIEW AND WILL BE                      

 SCHEDULED FOR THE OCT 93 CONFIGURATION CONTROL BOARD.  CG 70-73                

 ARE TENTATIVELY SCHEDULED TO RECEIVE THE ECP DURING PSA.  BACKFIT              

 OF THESE MODS TO THE PRAIRIE AND MASKER COOLERS ON CG 47-69 WILL               

 BE INCLUDED IN SHIPALT 47-435K WHICH IS CURRENTLY UNDER                        

 DEVELOPMENT BY ACPY.  TENTATIVE SCHEDULE IS TO START INSTALLATION              

 OF SHIPALT 47-435K IN FY 96.                                                   

                                                                                

 5.  ORIG POC IS MR. N. SMITHSON, PMS400F511, DSN 332-5959 OR COMM              

 (703) 602-5959.//