Home » Boiler Tube Failure Handbook » Waterwall
Location: Waterwall
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Appearance |
Observation |
Locations |
Mechanism |
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Bulging tube adjacent to field weld |
Bulging » Deformation
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Waterwall |
Long-term Overheat |
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Metal thinning on fireside |
Deformation » Thinning
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SuperheaterWaterwall |
Smelt/Slag Attack |
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External wastage beneath adherent slag deposit |
Deformation » Thinning
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SuperheaterWaterwall |
Corrosion From Slag Attack |
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ID pitting with corrosion tubercles |
Holes, Pits, Gouges » Waterside
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ReheaterSuperheaterWaterwall |
Oxygen Pitting |
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Undercut corrosion, multi-color deposits (red, white, black). (This is a view of a tube ID following cleaning.) |
Holes, Pits, Gouges » Waterside
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Waterwall |
Acid Phosphate Attack |
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Defect at weld bar attachment |
Fireside/Material Flaw » Holes, Pits, Gouges
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Waterwall |
Weld/Materials Defect |
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Thinning from the fireside, pockmarks on external surface |
Fireside » Holes, Pits, Gouges
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Waterwall |
Fireside Corrosion |
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Metal wastage |
Fireside » Holes, Pits, Gouges
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Waterwall |
Fireside Corrosion |
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Catastrophic failure associated with weld overlay |
Cracking » In or near weld or attachment » Transverse
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Waterwall |
Hydrogen Damage |
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Circumferential cracking |
Cracking » Not in or near a weld or attachment » Transverse
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Waterwall |
Thermal Fatigue |
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Forming lap at tube OD |
Cracking » Longitudinal » Not in or near a weld
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Waterwall |
Material Defect |
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Fish-mouth opening |
Cracking » Longitudinal » Not in or near a weld
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Waterwall |
Hot Tensile Overload |
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Thick-lipped rupture, may be very large window missing or a flap hanging by one edge |
Holes, Pits, Gouges
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Waterwall |
Hydrogen Damage |
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Longitudinal crack at bend |
Cracking » Not in or near a weld or attachment
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ReheaterSuperheaterWaterwall |
Long-term Overheat |
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Multiple cracks associated with attachment on outside of tube |
Cracking » In or near weld or attachment » Longitudinal or Random
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EconomizerWaterwall |
Corrosion Fatigue |
|
Longitudinal ID corrosion-fatigue cracks |
Cracking » In or near weld or attachment » Longitudinal
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Waterwall |
Corrosion Fatigue |
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Cracks close to attachments |
Cracking » In or near weld or attachment » Longitudinal
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Waterwall |
Corrosion Fatigue |
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Severe corrosion gouging at a weld-backing ring |
Holes, Pits, Gouges » Water/Steam Side
|
Waterwall |
Caustic Gouging |
|
Bulging tube adjacent to field weld |
Bulging » Deformation
|
Waterwall |
Long-term Overheat |
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Appearance |
Observation |
Location |
Mechanism |