Study the causes of failure of furnace wall tube in thermal power plant (part I)‎

Abstract EN

The failure of furnace wall tubes, boiler 6 –Najibia power station on March 2005 leading to plant shutdown was investigated.

The present work deals with the experimental investigation to recognize the causes of failure.

These included : 1- Determination of scale density and its compositional analysis, 2-Spectrometric analysis of tube alloy material, 3-Mechanical testing of tubes material and 4-Examination of microstructure of the alloy.

The results indicated that the recorded internal scale density ~ 45 mg / cm2 may interfere with the heat transfer process leading to overheating.

The loss of some alloying elements due to excessive heating reduces the strength of the alloy.

An increase of hardness was detected to (720-800 HV) at the failed side which reflects the effect of metal hardening.

Furthermore, the microstructural examination indicated the phase transformation of the pearlite to the martensite which confirmed the hardening effect leading to tube brittleness then rupture thereafter.

The probable causes of tube failure were discussed.