Home » Boiler Tube Failure Handbook » Cracking

Observation: Cracking

	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 » Not in or near a weld » Transverse	Studded Waterwall	Thermal Fatigue
	Circumferential cracking	Cracking » Not in or near a weld or attachment » Transverse	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	ReheaterSuperheaterWaterwall	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	Dissimilar Metal Weld CreepThermal Fatigue
	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	EconomizerWaterwall	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