Descaling Procedure for Jacket Cooling Water System of Marine Internal Combustion Engines

Chemical Dosing

Use proper Personnel Protective Equipment such as chemical gloves, face mask, goggles, etc.

Chemical Material Safety Data Sheet (MSDS) to be read well before starting the procedure.
Chemical Material Safety Data Sheet (MSDS) to be read well before starting the procedure.
  • Isolate the system to be cleaned (For example Jacket Cooling Water System)
  • Prepare one pump (Chemical Resistant) and hose (Preferably transparent to observe flow of chemical) and connect lowest point in the system to one end of the hose. (In the case of diesel engine jacket cooling system, jacket water drain is the lowest point). Other end of the hose is connected to the discharge side of the pump.
  • From the highest point of the system connect another hose to the chemical mixing drum. This is the return line.
  • A 200 liter chemical resistant drum can be used as chemical mixing drum.
  • Take proper descaling chemical ("Descaling Liquid" is a product from UNITOR) and prepare a solution of 10 parts of chemical with 90 parts of distilled water, in the chemical mixing drum.

Remember to close and secure valves for isolating system before descaling.
Remember to close and secure valves for isolating system before descaling.
Mild scale deposits in an Auxiliary Engine Lubricating Oil Cooler
Mild scale deposits in an Auxiliary Engine Lubricating Oil Cooler
  • Keep a sample of the solution from chemical mixing drum so that it can be compared with the change in colour during descaling process.
  • Now start the pump. Pump take suction from the chemical mixing drum, it is discharged to the lowest point in the system and chemical solution is returned back through the highest point in the system to the chemical mixing drum.
  • When solution starts coming through the return line start jacket water pre-heating and gradually increase the temperature of the solution to 50 - 60 Degree Celsius.
  • Keeping the temperature of the solution at the prescribed value, continue circulation of chemical for about 5 hours.
  • Drain the system completely.
  • Fill up the drum with clean fresh water and start the pump. Run the pump for 10 minutes.
  • Drain again the system, and open up the inspection covers of the equipment and check for any deposits due to descaling. Remove any deposits if present and clean it up. Put back the inspection covers.
  • Since the descaling chemical used are acidic in nature, it must be neutralized with suitable chemicals (Such as "Alkalinity Control" from UNITOR).
  • Circulate the alkalinity control chemical solution through the system and check for PH frequently. A PH value of 7 to be attained.
  • Drain the solution completely from the system.

A Shell and Tube heat exchanger after descaling
A Shell and Tube heat exchanger after descaling
  • Flush the system once again with fresh water. Drain the system.
  • Disconnect all the lines and equipment, put back any blanks if removed.
  • Add chemical inhibitors such as "Rocor NB Liquid" (Liquid form) or "Dieselguard NB" (Powder form) and increase the nitrite level to 1000-2400ppm, pH:8.6-10.0 and Chloride levels 50ppm or less.
  • All the above parameters to be monitored once the system is put back into the operation.

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sebi 3 years ago

good..keep posting..

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