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CHEMICAL CLEANING OF BOILER IS CARRIED OUT IN THREE CONDITION :-

1.  BEFORE INITIAL START OF BOILER.
2.  IN CASE OF HEAVY OIL CONTAMINATION.
3.  IN CASE OF HEAVY SCALING OR CORROSION.

ALKALINE BOILING OUT IS CARRIED OUT BY TRI-SODIUM PHOSPHATE OR CAUSTIC SODA 2500 PPM EACH. THIS IS CARRIED OUT IN CASE OF OIL CONTAMINATION OF BOILER WATER.

PROCEDURE:-

1. FILL WATER TO NORMAL LEVEL WITH FEED WATER USED FOR REGULAR SERVICE. WATER SHOULD BE DEAERATED.
2.  CHEMICAL USED FOR BOILING OUT SHOULD BE COMPLETELY DISSOLVED BEFORE THEY ENTER THE UNIT AND FED BY CHEMICAL FEED CONNECTION.
3. START FIRING THE BOILER SLOWLY.
4.  PRESSURE TO BE RAISED SLOWLY AND AT CONSTANT RATE TILL 3.5 TO 4 BAR MINIMUM.
5.  BOILER TO BE BLOWDOWN AT LEAST ONCE EVERY 8 HOURS DURING BOILING OUT.
6.  HALF OF GAUGE GLASS TO BE BLOW DOWN TOTALLY AND DIVIDED EQUALLY IN ALL MAIN BLOW DOWN.
7.  AT END OF BLOW DOWN , WATER IS BROUGHT BACK TO SAME LEVEL AS NORMAL AND REPLENISHED WITH CHEMICAL TO PROPER CONCENTRATION.
8.  TO BE DONE TILL NO CONTAMINATION ARE PRESENT IN WATER SAMPLE FROM BLOW DOWN LINES.