Failure analysis of water wall tubes in coal fired power plant

One of power generating utility has reported the failure of boiler water wall tubes after a service life of 10,000 hours against the design life of 30-35 years. The failure of tubes was reported in water wall tubes regions which consist of carbon steel alloy. These boiler tubes were operating under the oxidizing/ reducing atmosphere at high temperature and pressure. This paper represents the investigation the failure of water wall tubes used in a coal fired thermal power plant. The failure investigation covers visual inspection, dimensional measurement, hardness mapping, deposit flux measurement and SEM & EDX analysis of the deposited products. This paper is the case study of failure analysis of water wall tubes due to corrosion and ID deposition on the tube. The analysis reveals that the failures were due to inside corrosion and hydrogen damage attack.