Classification of Boiler Tube Failure Reasons
Classification of Boiler Tube Failure Reasons
Reason for the failure of boiler water wall, super-heater & re-heater tubes :
A. STRESS RUPTURE
1. Short term overheating
2. High temperature creep
3. Dissimilar metal weld /stress rupture
B. WATER SIDE CORROSION
1. Caustic Corrosion
2. Hydrogen damage
3. Surface pitting /Localized corrosion
4. Stress corrosion cracking
C. FIRE SIDE CORROSION
1. Low temperature corrosion due to “DUE POINT” (sulpher presence in fuel)
2. Water wall corrosion
3. Coal ash effect
4. Oil ash effect
D. ERROSION
1. Fly ash
2. Fouling/slagging
3. Soot blowing
4. Coal particle impingement
5. Flame impingement
E. FATIGUE
1. Thermal , 2. Vibration, 3. Corrosion
F. LACK OF QUALITY CONTROL
1. Maintenance tube cleaning damage
2. Short blasting/ hydro jet cleaning/weld
3. Position grinding/ pressure part gas cutting
4. Chemical excursion damage
5. Material defect
6. Welding defect
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