WI 501 Ref 2.5 Drew Removal of Corrosion Products T-AKE.doc

LIQUIDEWT to DREWGARD CWT Conversion Procedure

For

Military Sealift Command Vessel T-AKE Class

1. Ensure adequate time and resources are available for the job. To clean and treat a typical cooling system will require three complete volumes of water one of which must be distilled. Typical cleaning time including draining will take between 14-24 hours. Determine the expected degree of cleaning that will occur. Agree upon the time frame to perform the cleaning. Ascertain that there are sufficient and proper equipment and labor resources to achieve the outcome. If heating is required, determine that there are sufficient sources of heating and that the heating can be maintained throughout the cleaning period.

2. Drain the cooling system and dispose of in accordance to MSC policy. Note that storage totes or other suitable storage tanks may be required to hold the spent cooling solution for proper disposal.

Cleaning Cooling Systems (Out of Service) A. Where possible, connect the discharge side of the circulating pump to the lowest practical point on the cooling system using a length of flexible hose and the appropriate fittings. Using a second section of flexible hose with fittings, connect a cleaning solution return with a valve from the highest point on the cooling jacket system to the top of the mixing tank, which is the suction supply for the circulating pump. Refer to Cleaning Specification for exact piping configuration B. Fill and leak test the circuit prior to adding FERROCLEAN. If the system is tight commence cleaning procedure as follows

C. Heat the water before adding the FERROCLEAN and commencing the cleaning until it reaches a temperature of 60-82°C (140-180°F). The heat can be provided by a heating coil or steam line in the cleaning solution mixing tank or a system heat exchanger.

D. Add the 2% FERROCLEAN solution as per attached table for the system being cleaned. Note; it is best to cross connect the HT and LT chill water as well as the HT and LT Freshwater. In this way, only two flushes are required. This will save on man hours and set up time required for draining and filling multiple systems. Note; FERROCLEAN cleaning treatment will be added to the mixing tank to prepare the required proportions of cleaning solution based on the water volume in the system. An equal amount of water will need to be drained from the system before adding the FERROCLEAN cleaning treatment.

E. Be sure all valves in the mixing tank, pump, return and vent system are open. Ensure all coolers and heat exchangers in the cleaning loop. Start the chemical circulating pump and adjust the flow rate so that the level of the solution in the mixing tank remains constant.

F. Continue circulation and maintain the cleaning solution temperature for a minimum of 12 hours. As the cleaning progresses after adding FERROCLEAN cleaning treatment, the system water may start to change to a dark green/black color. The system pH will initially drop to 5.0 - 6.0. If foaming should occur, DREWPLUS L-474 may be added tot eh solution mixing tank in 250 ml increments to control foaming. The result of this product is almost immediate and as such can be managed manually as needed.

G. Throughout the circulation period, pH of the solution should be checked periodically to ensure the solution has adequate reserve for the cleaning. If the pH reaches 7.0 or higher the solution may be “spiked” one time with an additional 0.5% FERROCLEAN. If the cleaning time is approaching 12 hours and the pH is reaching neutral (pH 7.0) the flush is considered complete.

H. Drain the system then refill with fresh water and approximately 0.1% solution of GC (refer to Table 2). This solution will neutralize any remaining FERROCLEAN in the system and aid in the flushing process. Circulate the GC solution for a period of at least one hour but not more than three. Once this time has elapsed continue flushing the system with fresh water while draining until the discharge water is completely clear.

I. Inspect the cooling system interior for cleanliness. Repeat the procedures if the system is not completely clean.

J. Disconnect the vent system and the cleaning system from the circuit. Secure all inlet and outlet cleaning points.

K. Once flushing operation is completed fill cooling system with good quality make up (less than 10µmhos conductivity).

L. Add DREWGARD CWT at 8.0 liters/ton of system capacity. This should provide a silica level of +/- 350-450 ppm

Table 1

Table 2

2 Cleaning strength based on relative iron content seen in lab analyses from AMELIA EARHART samples

DREWGARD CWT requirement

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