Boiler Tube Failure Handbook

Appearance Observation Locations Mechanism
Bulging tube adjacent to field weld Bulging tube adjacent to field weld »
Metal thinning on fireside Metal thinning on fireside »
External wastage beneath adherent slag deposit External wastage beneath adherent slag deposit »
External thinning, smooth areas External thinning, smooth areas »
Smooth surface Smooth surface »
General pitting General pitting »
ID pitting with corrosion tubercles ID pitting with corrosion tubercles »
sharply defined hole sharply defined hole »
Severe corrosion on side of tube facing gas turbine/duct burners Severe corrosion on side of tube facing gas turbine/duct burners »
Undercut corrosion, multi-color deposits (red, white, black). (This is a view of a tube ID following cleaning.) Undercut corrosion, multi-color deposits (red, white, black). (This is a view of a tube ID following cleaning.) »
Thinning on inside of a U-bend or other change in direction Thinning on inside of a U-bend or other change in direction »
Defect at weld bar attachment Defect at weld bar attachment »
Porosity in weld Porosity in weld »
Thinning from the fireside, pockmarks on external surface Thinning from the fireside, pockmarks on external surface »
Metal wastage Metal wastage »
Catastrophic failure associated with weld overlay Catastrophic failure associated with weld overlay » »
Fine cracks around studs Fine cracks around studs » »
Circumferential cracking Circumferential cracking » »
Forming lap at tube OD Forming lap at tube OD » »
Multiple tight fine cracks Multiple tight fine cracks » »
Fish-mouth rupture Fish-mouth rupture »
Fish-mouth opening Fish-mouth opening » »
Thick-lipped rupture, may be very large window missing or a flap hanging by one edge Thick-lipped rupture, may be very large window missing or a flap hanging by one edge
Irregular cracking Irregular cracking »
Short longitudinal cracks with numerous parallel cracks Short longitudinal cracks with numerous parallel cracks » »
Multitude of cracks parallel to tube Multitude of cracks parallel to tube » »
Longitudinal crack at bend Longitudinal crack at bend »
Transverse cracking in the rolled portion of tube where it is inserted into the drum Transverse cracking in the rolled portion of tube where it is inserted into the drum
Complete failure at weld Complete failure at weld » »
Transverse crack near support Transverse crack near support » »
Brittle fracture in heat affected zone of a weld Brittle fracture in heat affected zone of a weld » »
Multiple cracks associated with attachment on outside of tube Multiple cracks associated with attachment on outside of tube » »
Longitudinal ID corrosion-fatigue cracks Longitudinal ID corrosion-fatigue cracks » »
Longitudinal cracks adjacent to weld Longitudinal cracks adjacent to weld » »
Thick-lipped rupture and adjacent longitudinal fissuring Thick-lipped rupture and adjacent longitudinal fissuring » »
Deformation and perforation from the outside in Deformation and perforation from the outside in »
Complete weld separation Complete weld separation » »
Cracks close to attachments Cracks close to attachments » »
Severe corrosion gouging at a weld-backing ring Severe corrosion gouging at a weld-backing ring »
Severe pock-marked corrosion on fireside Severe pock-marked corrosion on fireside
Bulging tube adjacent to field weld Bulging tube adjacent to field weld »
Appearance Observation Location Mechanism