Metallurgical Failure Investigation of Premature Failed Platen Water Wall Tube in a Thermal Power Plant Boiler

The failure investigation of platen water wall in the boiler is presented in this article. The platen water wall is primarily used for pre-heating the boiler feed water, and this preheated water is enter into economizer, evaporator and superheater section to produce the steam. The occurrence of failure in the water wall tube is investigated to prevent the reoccurrence of similar failure in near future. The comprehensive analysis like visual inspection, dimensional measurement, chemical analysis, hardness evaluation, metallography and mechanical testing were conducted on the failed tube. It can be concluded from various test results that graphitization is root cause of the failure, as temperature exposure of platen water wall tube was high for long period of service. Various evidence pertaining to graphitization failure were discussed in this article. Preventive measures were also suggested the minimize similar failure in near future.