Home » Boiler Tube Failure Handbook » Cracking Observation: Cracking Filter Items by: Observation Location Mechanism Appearance Observation Locations Mechanism Catastrophic failure associated with weld overlay Cracking » In or near weld or attachment » Transverse Waterwall Hydrogen Damage Fine cracks around studs Cracking » Transverse » Not in or near a weld Studded Waterwall Thermal Fatigue Circumferential cracking Cracking » Transverse » Not in or near a weld or attachment Waterwall Thermal Fatigue Forming lap at tube OD Cracking » Longitudinal » Not in or near a weld Waterwall Material Defect Multiple tight fine cracks Cracking » Longitudinal » Not in or near a weld Superheater Stress Corrosion Cracking Fish-mouth rupture Cracking » Not in or near a weld ReheaterSuperheater Short-Term Overheat Fish-mouth opening Cracking » Longitudinal » Not in or near a weld Waterwall Hot Tensile Overload Irregular cracking Cracking » Not in or near a weld Superheater Creep Short longitudinal cracks with numerous parallel cracks Cracking » Longitudinal » Not in or near a weld or attachment ReheaterSuperheater Long-term Overheat/Creep Multitude of cracks parallel to tube Cracking » Longitudinal » Not in or near a weld or attachment Superheater Long-term Overheat/Creep Longitudinal crack at bend Cracking » Not in or near a weld or attachment WaterwallReheaterSuperheater Long-term Overheat Transverse cracking in the rolled portion of tube where it is inserted into the drum Near or in weld or attachment Riser tube at rolled connection in drum Caustic Induced Stress Corrosion Cracking Complete failure at weld Cracking » In or near weld or attachment » Transverse Superheater Thermal FatigueDissimilar Metal Weld Creep Transverse crack near support Cracking » In or near weld or attachment » Transverse Evaporator Thermal Fatigue Brittle fracture in heat affected zone of a weld Cracking » In or near weld or attachment » Transverse or Random ReheaterSuperheater Graphitization Multiple cracks associated with attachment on outside of tube Cracking » In or near weld or attachment » Longitudinal or Random WaterwallEconomizer Corrosion Fatigue Longitudinal ID corrosion-fatigue cracks Cracking » In or near weld or attachment » Longitudinal Waterwall Corrosion Fatigue Longitudinal cracks adjacent to weld Cracking » In or near weld or attachment » Longitudinal or Random Superheater Wrong material/Creep Thick-lipped rupture and adjacent longitudinal fissuring Cracking » Longitudinal » Not Near Weld ReheaterSuperheater Creep Complete weld separation Cracking » In or near weld or attachment » Transverse Superheater Dissimilar Metal Weld Failure (DMW) Cracks close to attachments Cracking » In or near weld or attachment » Longitudinal Waterwall Corrosion Fatigue Appearance Observation Location Mechanism
