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To establish a standard procedure for passivation of purified water system installed in plant room.
Precautions:
> Concerned personnel should be trained on the SOP.
> The operator & supervisor should wear acid proof apron, hand gloves, eye protection glass & head / foot wear while handling the acid.
RO feed water tank and RO system:
The following steps should be carried out for passivation of RO feed water tank and circulation pipes with valves.
Drain the water from the RO feed water tank by opening drain valve. Close the drain valve after draining.
Open the valve of the RO feed water tank from PLC and fill the tank approximately 50% with 750 liters of water.
Disconnect the pipes from inlet of RO pump & connect to the cleaning pump.
Isolate the EDI inlet & out let pipelines & inter connect the same line.
Measure 65 liters of 64% concentrated HNO3 and slowly add under stirring into RO feed water tank containing 750 liters of water. This will be approximately 5.1% v/v.
Transfer the nitric acid from container to the feed water tank by acid proof pump with proper care.
Disconnect the acid transfer pump. Remove the same from the place.
Start the cleaning cycle from PLC.
Note the timing. Then check that the water is passing through the RO/ Filter housing & connected pipelines. This cycle should continue for 1 hour.
After 1 hour, stop the cleaning cycle. Then open the drain valves and drain the solution.
Take fresh water in the tank & start the pump. Flush the system for 1 hour. Then open the drain valves and continue draining the water till acid solution is completely drained out.
Offer the water from the drain points to QC for analysis. On receipt of NIL stresses of Nitric acid report, stop the pump and disconnect the cleaning pump.
Install the RO membrane & Micron filters to the respective housing.
Drain the water from RO/ filter housing & pipelines.
Purified water storage tank and distribution loops:
The following works are to be carried out for passivation of purified water storage tank and distribution loops with valves. The operator & supervisor should wear acid proof apron, hand gloves, eye protection glass & head / foot wear while handling the acid.
Open the valve of the purified water storage tank from PLC and fill the tank approximately 50% with 2000 litters of water.
Measure 175 liters of 64% concentrated HNO3 and slowly add under stirring into purified water storage tank containing 2000 liters of water. This will be approximately 5.1% v/v.
Transfer the nitric acid from container to the water tank by acid proof pump with proper care.
Disconnect the acid transfer pump. Remove the same from the place.
Start both the water circulation pumps from the operating panel.
Note the timing; check the pressure of pipeline from the gauge. It should be between 3.5 to 5.0 kg/ cm². This cycle should continue for 1 hour.
After 30 minutes of running the cycle, start draining the solution (1-2 L) from each user point and drain point.
On completion of the 1 hour cycle & draining of all user points, stop the circulation pumps. Then open the drain valve of the tank and drain the acid solution.
Start the RO system. Fill the purified water storage tank with water and start the circulation pumps.
Flush all the drain points & user points for 2 to 5 minutes.
Offer the water from the drain points to QC for analysis. On receipt of NIL stresses of Nitric acid report, stop the pump and drain out the water
