Home » Boiler Tube Failure Handbook » Cracking Observation: Cracking Filter Items by: Observation Location Mechanism Appearance Observation Locations Mechanism Catastrophic failure associated with weld overlay Transverse » In or near weld or attachment » Cracking Waterwall Hydrogen Damage Fine cracks around studs Not in or near a weld » Cracking » Transverse Studded Waterwall Thermal Fatigue Circumferential cracking Not in or near a weld or attachment » Cracking » Transverse Waterwall Thermal Fatigue Forming lap at tube OD Not in or near a weld » Cracking » Longitudinal 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 SuperheaterReheater 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 » Not in or near a weld or attachment » Longitudinal SuperheaterReheater Long-term Overheat/Creep Multitude of cracks parallel to tube Cracking » Not in or near a weld or attachment » Longitudinal Superheater Long-term Overheat/Creep Longitudinal crack at bend Not in or near a weld or attachment » Cracking WaterwallSuperheaterReheater 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 Transverse » In or near weld or attachment » Cracking Superheater Thermal FatigueDissimilar Metal Weld Creep Transverse crack near support Transverse » In or near weld or attachment » Cracking Evaporator Thermal Fatigue Brittle fracture in heat affected zone of a weld In or near weld or attachment » Cracking » Transverse or Random ReheaterSuperheater Graphitization Multiple cracks associated with attachment on outside of tube In or near weld or attachment » Cracking » Longitudinal or Random EconomizerWaterwall Corrosion Fatigue Longitudinal ID corrosion-fatigue cracks In or near weld or attachment » Cracking » Longitudinal Waterwall Corrosion Fatigue Longitudinal cracks adjacent to weld In or near weld or attachment » Cracking » Longitudinal or Random Superheater Wrong material/Creep Thick-lipped rupture and adjacent longitudinal fissuring Cracking » Longitudinal » Not Near Weld ReheaterSuperheater Creep Complete weld separation Transverse » In or near weld or attachment » Cracking Superheater Dissimilar Metal Weld Failure (DMW) Cracks close to attachments In or near weld or attachment » Cracking » Longitudinal Waterwall Corrosion Fatigue Appearance Observation Location Mechanism
