Corrosion Failure Reason of Boiler Water-cooling Wall

Three high peressuer boilers in a petrochemical factory were shut down because of corrosion bursting of water wall, which affected the safety of operation of the unite. A analysis results showed that, the boiler corrosion was mainly caused by alkali corrosion, the inner surface passivation protective films of boiler water-wall tubes corroded by high concentration alkaline medium, and corrosive ulcer formed in the tube wall, which led to coutineous thinning of the tube wall. Finaly the tube bursted when the pressure and the temperature of steam were overloaded.