DDG 51 CLASS ADVISORY NR 11-95
INTERIM FLUSHING PROCEDURES FOR PRAIRIE, MASKER AND START AIR COOLERS.
*** CANCELLED *** PER Program Executive Officer
*** Reason: EOSS Procedures BMPA, BSAA, MUTA and MUTS were updated, along
with PMS.
REF/A/DOC/NAVSEA/01SEP92//
REF/B/DOC/NSWCCD-SSES/-//
NARR/REF A IS NSTM 254, CONDENSERS, HEAT EXCHANGERS AND AIR EJECTORS.
REF B IS PMS CARD MRC 5516/B9 W61RN, LU-1, AIR COOLERS.//
RMKS/1. THIS CLASS ADVISORY PROVIDES INTERIM FLUSHING PROCEDURES FOR
THE PRAIRIE, MASKER AND START AIR COOLERS IN ORDER TO IMPROVE BLEED
AIR SYSTEM RELIABILITY.
2. BACKGROUND.
A. GAS TURBINE BLEED AIR (B/A) SYSTEMS HAVE EXPERIENCED A
HISTORY OF FAILED B/A VALVES. THE PRIMARY CAUSE OF VALVE FAILURE
IS SALT WATER INTRUSION INTO THE B/A SYSTEM THROUGH DETERIORATED
PRAIRIE, MASKER AND START AIR COOLER TUBE BUNDLES. THE HIGH
OPERATING TEMPERATURE OF THE B/A SYSTEM CAUSES INTRUDED SEAWATER TO
EVAPORATE AND DEPOSIT A HARD SCALE ON THE AIR SIDE OF THE ENTIRE
SYSTEM. THIS SCALE FORMS NOT ONLY ON THE TUBE BUNDLE BUT ALSO
CONTAMINATES EVERY VALVE THROUGHOUT THE SYSTEM. TO DECONTAMINATE THE
SYSTEM, ALL OF THE CONTAMINATED VALVES MUST BE OPENED/CLEANED AND THE
ENTIRE PIPING SYSTEM FLUSHED.
B. PRESENTLY EOSS PROCEDURES MUTS AND MUTA DIRECT SECURING
SEAWATER FLOW THROUGH BLEED AIR COOLERS WHENEVER SHIPS SECURE FROM
UNDERWAY OPERATIONS. SECURING SEAWATER FLOW THROUGH THE COOLERS
MINIMIZES EROSION OF THE TUBE MATERIAL (90-10 CUNI). THE PROBLEM
WITH THIS LAYUP PROCEDURE IS WHEN WATER STAGNATES IN THE COOLER, THE
TUBES ARE FOULED BY MARINE GROWTH. A REDUCTION OF THE OXYGEN
CONCENTRATION IN THE AREAS OF MARINE GROWTH AND IN COOLER CREVICES
LEADS TO A BREAKDOWN OF THE CORROSION INHIBITING CUPROUS OXIDE FILM
THAT FORMS ON PIPING SURFACES. THE FORMATION AND PRESERVATION OF
THIS CORROSION INHIBITING OXIDE FILM ARE KEYS TO LONG TERM COOLER
TUBE SERVICE LIFE. ANOTHER PROBLEM WITH MARINE GROWTH INSIDE COOLERS
IS CLOGGING OF TUBE BUNDLES AND RESTRICTION OF NORMAL SEAWATER FLOW.
THIS CLOGGING ALSO CAUSES TURBULENT FLOW INSIDE THE TUBE BUNDLES AND
RESULTS IN ACCELERATED EROSION. PERIODIC CIRCULATION OF WATER INSIDE
THE PRAIRIE, MASKER AND START AIR HEAT EXCHANGERS WILL DISCOURAGE
MARINE GROWTH WHICH ATTACKS THE PROTECTIVE CUPROUS OXIDE LAYER.
3. ACTION. DDG 51 CLASS SHIPS SHALL LAYUP PRAIRIE, MASKER AND START
AIR COOLERS WHEN THE BLEED AIR SYSTEM IS TO BE SECURED FOR GREATER
THAN 72 HOURS. THE FOLLOWING GUIDANCE APPLIES:
A. IF THE B/A SYSTEM IS TO BE SECURED FOR GREATER THAN 72 HOURS
BUT LESS THAN ONE WEEK, PERFORM THE FOLLOWING:
(1) UPON SECURING FROM UNDERWAY OPERATIONS, SHUT THE COOLER
ISOLATION VALVES IAW EOSS PROCEDURE BMPA.
(2) PLACE CAUTION TAGS ON THE PACC/SCU GTM START PUSHBUTTONS,
EPCC GTG START PUSHBUTTONS, GTG 14TH STAGE BLEED AIR SELECTOR SWITCH
AND THE GTG LOCOP:
BLEED AIR COOLERS ARE ISOLATED. ENSURE SEA
WATER IS ALIGNED TO THE COOLER PRIOR TO B/A SYSTEM
OPERATION.
(3) OPEN THE ISOLATION VALVES AND CIRCULATE SEA WATER THROUGH
THE COOLER FOR TEN MINUTES ONCE A DAY TO REMOVE STAGNATED SEA WATER
IAW REF A PARA 254-2.4.12.2.1. RECLOSE THE ISOLATION VALVES WHEN
COMPLETE. THE COOLERS SHALL REMAIN ISOLATED UNTIL THE B/A SYSTEM IS
TO BE ACTIVATED OR THE SHIP IS MAKING PREPARATIONS TO GET UNDERWAY.
B. IF THE B/A SYSTEM IS TO BE SECURED FOR GREATER THAN ONE WEEK
BUT LESS THAN FOUR MONTHS, PERFORM LAYUP PROCEDURES IAW REF A PARA
254-2.4.12.2.2. REF A REQUIRES THE COOLERS TO BE DRAINED AND
IMMEDIATELY FILLED WITH FRESH WATER WHICH IS CHANGED EVERY TWO WEEKS
TO PREVENT STAGNATION. FILL COOLER WITH FRESH WATER UNTIL WATER
APPEARS AT THE VENT, DRAIN AND REFILL. REINSTALL THE VENT PLUG. IF
THE HEAT EXCHANGER IS NOT EQUIPPED WITH FILL AND DRAIN PLUGS, THEN
CONTINUE WITH THE FLUSHING TECHNIQUE PROVIDED IN PARA 3.A.
C. IF THE BLEED AIR SYSTEM IS TO BE SECURED FOR GREATER THAN 4
MONTHS, OPEN AND CLEAN THE PRAIRIE, MASKER, AND START AIR COOLER
SEAWATER SIDES IAW REF B. AFTER CLEANING, LEAVE THE SEAWATER SIDES
DRAINED. REINSTALL THE PLUGS. IF THE HEAT EXCHANGER IS NOT EQUIPPED
WITH FILL AND DRAIN PLUGS, THEN CONTINUE WITH THE FLUSHING TECHNIQUE
PROVIDED IN PARA 3.A.
D. ENSURE THE PRIOR TO UNDERWAY CHECK OFF LIST INCLUDES
ALIGNING THE PRAIRIE, MASKER AIR AND START AIR COOLERS PRIOR TO
OPERATION OF THE BLEED AIR SYSTEM.
E. ENSURE THE B/A LOW POINT DRAINS ARE FREE OF DEBRIS AND IN
WORKING CONDITION.
F. AVOID FRESH WATER CONTAMINATION - 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 WHILE FILLING.
G. SHIPS WITH SUSPECTED BLEED AIR COOLER TUBE LEAKAGE SHOULD
TEST COOLERS IAW REF A PARA 254-2.6.12. A MAXIMUM OF 10 PERCENT OF
EACH HEAT EXCHANGER TUBES MAY BE PLUGGED PRIOR TO RETUBING/REPLACING
THE ENTIRE HEAT EXCHANGER TUBE BUNDLE.
4. FOR COMNAVSURFLANT/COMNAVSURFPAC - RECOMMEND TASKING DDG 51 CLASS
SHIPS TO ADHERE TO PARA 3 ACTIONS.
5. FOR NSWCCD-SSES:
A. DEVELOP AN AS REQUIRED PMS CHECK FOR MIP 5516 USING PARA 3
GUIDANCE AND REF A. PERIODICITY FOR NEW CHECK SHOULD BE AN AS
REQUIRED DAILY CHECK WHEN THE B/A SYSTEM IS SECURED FOR GREATER
THAN 72 HOURS.
B. MODIFY EOSS PROCEDURES MUTA, MUTS, BMPA, BSAA TO INCLUDE A
NOTE WHICH DISCUSSES THE LAYUP PROCEDURE DESCRIBED IN PARA 3.
6. THIS CLASS ADVISORY HAS NO IMPACT ON CMMP AND WILL BE CANCELLED
WHEN EOSS PROCEDURES BMPA, BSAA, MUTS AND MUTA HAVE BEEN MODIFIED AND
PMS HAS BEEN ESTABLISHED.
7. ORIG POC IS MR. N. SMITHSON, PMS400F511, DSN 332-5959 OR COMM
(703) 602-5959. HEAT EXCHANGER TPOC IS MR. W. AERNI, SEA 03X43, DSN
332-6794 OR COMM (703) 602-6794.//
BT
CG-47