Home » Boiler Tube Failure Handbook » Superheater Location: Superheater Filter Items by: Observation Location Mechanism Appearance Observation Locations Mechanism Metal thinning on fireside Deformation » Thinning WaterwallSuperheater Smelt/Slag Attack External wastage beneath adherent slag deposit Deformation » Thinning WaterwallSuperheater Corrosion From Slag Attack Smooth surface Deformation » Thinning ReheaterSuperheater Fly Ash Erosion ID pitting with corrosion tubercles Holes, Pits, Gouges » Waterside WaterwallReheaterSuperheater Oxygen Pitting Porosity in weld Holes, Pits, Gouges » Material Defect Superheater Weld 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 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 Complete failure at weld Cracking » In or near weld or attachment » Transverse Superheater Thermal FatigueDissimilar Metal Weld Creep Brittle fracture in heat affected zone of a weld Cracking » In or near weld or attachment » Transverse or Random ReheaterSuperheater Graphitization 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) Appearance Observation Location Mechanism
