Boilers
Boilers
(OP)
Details about phenomenon of Phos phate hide out in high pressure / low pressure steam generators/ Boilers
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RE: Boilers
If the unit is a high pressure boiler ( MCR drum pressure approx 2800 psig) much of the phosphate will precipitate out of solution onto the hot inside surface of boiler tubes if the tube wall temp is above ( 650 F ?). If the boiler is cycled to low pressures at night , the tube wall temperature and the boiler water saturation temperature drops below 600 F, such that the solubility of phosphate increases and the deposits on the tube surface will return to being dissolved in the boiler water. Tis then raises the phosphate concetraon well above the optimum, and forces teh operator to blowdwon large amounts of water to correct the phosphate ratio.
RE: Boilers
Hideout can be a precuror to corrosion fatigue, Hydrogen damage, acid phophate corrosion and caustic gouging. The last three take place in the high heat release zones.
Corrosion fatigue can be catastrophic failures if located in bends.