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Crevice Corrosion in a Subsea System — Aspect Before Analysis

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Aspect of the waterwall during removal of the leaking tube. The leakage was detected, by visual inspection, from the outside of the boiler.
1675
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Field photoDf - General View
Multiple thermal fatigue cracks at the welded joint between the smoke tube (vertical, internal diameter 248mm) and the tubesheet (horizontal, plate of 22 mm thickness). This is a view from the combustion chamber. The dye check tests revealed several parallel cracks.
1249
VIEW
ML00119 / Feb.2018
Thermal Fatigue of a Marine Boiler
M - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Cm - Aspect by NDTDf - Thermal Fatigue Cracks
Micrographic detail of the longitudinal section of the tube, close to the external surface. The carburizing layer consists of a bainitic structure, with intergranular and intragranular carbide precipitation.
1184
VIEW
ML00107 / Dec.2017
Carburized 9Cr1MoV Superheater Tube
M - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Cm - Nital Etched Micrography by OMDf - Carburized Layer
The micrography of the longitudinal section of the tube, close to OD, shows the paralel cracks, filled with oxides, perpendicular to the surface.
1441
VIEW
ML00104 / Dec.2017
Thermal Fatigue of a Boiler Tube
M - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
Cm - As polished micrographyDf - Close to the External Surface
The macrography of a longitudinal section of the shell plate (sample removed from the boiler), at the position of the fillet weld (sealing weld) with a tube, where surface welding repairs created conditions for cracking the base material in a transgranular morphology. Several cracks were identify starting from the steam drum internal surface.
448
VIEW
ML00019 / Apr.2017
Transgranular SCC in Boiler Steam Drum
M - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Transverse Section AspectDf - Cracks
Typical branched stress corrosion cracks in a low carbon steel, ferritic-pertlitic structure. The cracks are filled with corrosion products.
771
VIEW
ML00018 / Apr.2017
SCC in Boiler Steam Drum
M - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Branched Cracks
Steam drum presenting cracks in the shell, connecting tube holes.
1704
VIEW
ML00020 / Apr.2017
Intergranular SCC in Boiler Steam Drum Repair
M - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Cm - Aspect Before AnalysisDf - Cracking
The internal surface of the 2 1/2" thickness plate drum was welded to attach a baffle plate (1/4" thick) using two fillets (one in each side of the plate to shell), but the welding procedure was not suitable since cracks appeared underbead, although they were detected only after 6 month in operation, when the baffle was removed. The picture shows a macrography of the surface, with the cracking.
698
VIEW
ML00008 / Nov.2017
Cold Cracks in CMn Steel Pressure Vessel
M - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Cm - NItal Etched MacroDf - Cracking

More from these cases

ML00163 — Corrosion Fatigue of a Boiler Waterwall TubeM - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Aspect of the sample removed from the waterwall, where the tube has leaked, presenting the crack in the membrane.
361
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Field photoDf - Through Wall Cracking
Aspect of the tube internal surface after removal from the boiler, presenting multiple longitudinal cracks.
295
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Internal Surface
Aspect of the external surface of the leaking tube, after removal of the membrane.
262
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - External Surface
Throught wall cracking of the waterwall tube at the leakage position, thick edged, The external surface of the tube was grounded to remove the membrane and the cracking is associated to the tube attachement.
242
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - Transverse Section AspectDf - Thick-edged rupture
Macrography of the transverse section of the tube, in a position where the cracking was not yet through wall. The internal tube surface shows multiple corrosion fatigue cracks, parallel, under the weld of the membrane, probably related to the cold side of the tube (the cracks opened to the boiler outside). The external side of the tube presenting a small crack at the margem of the weld, suggesting also the action of thermal stresses.
214
VIEW
ML00163 / Jun.2020
Corrosion Fatigue of a Boiler Waterwall Tube
M - Low Carbon SteelP - Seamless tubeAp - BoilerCd - Corrosion Fatigue
Cm - NItal Etched MacroDf - Multiple cracks

+18 more from this case →

ML00119 — Thermal Fatigue of a Marine BoilerM - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Macrography of the plate (thickness 22mm, in horizontal position) to tube (thickness 12.5 mm, in vertical position) welded joint. The half V groove was welded from the top (position inside the combustion chamber) in five weld beads, and with a small fillet welded from the water side (ouside of the tube). Average hardness of the plate is 180HV1 (1kg), of the tube is 150HV1 and of the weld is 190HV1. Maximum hardness of the tube HAZ is 165HV1 and plate HAZ is 195HV1.
219
VIEW
ML00119 / Feb.2018
Thermal Fatigue of a Marine Boiler
M - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Cm - NItal Etched MacroDf - Welded Joint
Micrography of the plate in a longitudinal section, presenting a typical ferritic pearlitic structure, banded. The plate is 22 mm thick.
182
VIEW
ML00119 / Feb.2018
Thermal Fatigue of a Marine Boiler
M - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrography of the plate in a longitudinal section, presenting a typical ferritic pearlitic structure, banded.
165
VIEW
ML00119 / Feb.2018
Thermal Fatigue of a Marine Boiler
M - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of the ferritic pearlitic structure of the plate in the longitudinal section.
147
VIEW
ML00119 / Feb.2018
Thermal Fatigue of a Marine Boiler
M - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrography of the weld metal in the center os the weld. Columnar grains (of the previous austenite) with primary ferrite in the grain boundaries; ferrite with aligned second phases and acicular ferrite, intragranular.
136
VIEW
ML00119 / Feb.2018
Thermal Fatigue of a Marine Boiler
M - Low Carbon SteelP - Fabrication WeldAp - ShipCd - Thermal Fatigue
Cm - Nital Etched Micrography by OMDf - Weld Metal

+16 more from this case →

ML00107 — Carburized 9Cr1MoV Superheater TubeM - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Micrography of the longitudinal section of the tube, close to the internal surface. A thick scale is evident, but no microstructural changes compared to the center of the tube.
183
VIEW
ML00107 / Dec.2017
Carburized 9Cr1MoV Superheater Tube
M - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Cm - Nital Etched Micrography by OMDf - Bainite
Aspect of the superheater ND 1" tube that was in operation for about 35,000 hours and presented a thick deposit at the external surface.
211
VIEW
ML00107 / Dec.2017
Carburized 9Cr1MoV Superheater Tube
M - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Cm - Aspect Before AnalysisDf - General View
Micrography of a longitudinal section of the tube in the center of the thickness, showing a ferritic-bainitic structure of this CrMoV steel.
156
VIEW
ML00107 / Dec.2017
Carburized 9Cr1MoV Superheater Tube
M - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Cm - Nital Etched Micrography by OMDf - Bainite
Micrography of a longitudinal section of the tube in the center of the thickness, showing a ferritic-bainitic structure of this CrMoV steel.
137
VIEW
ML00107 / Dec.2017
Carburized 9Cr1MoV Superheater Tube
M - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Cm - Nital Etched Micrography by OMDf - Bainite
Micrography of a longitudinal section of the tube in the center of the thickness, showing a ferritic-bainitic structure of this CrMoV steel.
142
VIEW
ML00107 / Dec.2017
Carburized 9Cr1MoV Superheater Tube
M - Heat Resistant SteelP - Seamless tubeAp - BoilerCd - Carburization
Cm - Nital Etched Micrography by OMDf - Bainite

+9 more from this case →

ML00104 — Thermal Fatigue of a Boiler TubeM - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
The micrography of the longitudinal section of the tube, close to ID, shows the paralel cracks, filled with oxides, perpendicular to the surface.
229
VIEW
ML00104 / Dec.2017
Thermal Fatigue of a Boiler Tube
M - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
Cm - As polished micrographyDf - Close to the Internal Surface
The water wall tube, external diameter 60.3mm and thickness 3.9 mm, shows circunferential cracks in the middle of the section. Several other tubes have failed after 10 years in service.
716
VIEW
ML00104 / Dec.2017
Thermal Fatigue of a Boiler Tube
M - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
Cm - Aspect Before AnalysisDf - General View
Aspect of the internal surface of the tube after longitudinal cut. This position is out of the damage area and only a small amount of deposits is evident.
216
VIEW
ML00104 / Dec.2017
Thermal Fatigue of a Boiler Tube
M - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
Cm - Surface AspectDf - Internal Surface
Aspect of the internal surface of the tube after longitudinal cut. This position is at the damage area where a thick deposit is evident.
186
VIEW
ML00104 / Dec.2017
Thermal Fatigue of a Boiler Tube
M - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
Cm - Surface AspectDf - Internal Surface
Aspect of the external surface of the tube, presenting a large circunferential crack.
171
VIEW
ML00104 / Dec.2017
Thermal Fatigue of a Boiler Tube
M - Low Carbon SteelP - Autogenously Welded TubeAp - BoilerCd - Thermal Fatigue
Cm - Surface AspectDf - External Surface

+16 more from this case →

ML00019 — Transgranular SCC in Boiler Steam DrumM - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Schematic drawing presenting the longitudinal section of the shell plate (sample removed from the boiler), at the position of the fillet weld (sealing weld) with a tube, where surface welding repairs created conditions for cracking the base material in a transgranular morphology. Several cracks were identify starting from the steam drum internal surface.
120
VIEW
ML00019 / Apr.2017
Transgranular SCC in Boiler Steam Drum
M - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Identification drawingDf - Cracks
Micrography of a transverse section of the shell plate in a cracked position showing the transgranular morphology of the stress corrosion cracks.
167
VIEW
ML00019 / Apr.2017
Transgranular SCC in Boiler Steam Drum
M - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by SEMDf - Transgranular Cracking
Micrography of the shell plate in the longitudinal section. Ferritic-perlitic microstructure.
96
VIEW
ML00019 / Apr.2017
Transgranular SCC in Boiler Steam Drum
M - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of the shell plate in the longitudinal section. Ferritic-perlitic microstructure.
89
VIEW
ML00019 / Apr.2017
Transgranular SCC in Boiler Steam Drum
M - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrography of the cracking showing the branched nature, typical of a stress corrosion cracking. The cracks started from the internal surface of the steam drum.
94
VIEW
ML00019 / Apr.2017
Transgranular SCC in Boiler Steam Drum
M - CMn SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Branched Cracks

+4 more from this case →

ML00018 — SCC in Boiler Steam DrumM - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Ferritic perlitic structure of the shell plate.
207
VIEW
ML00018 / Apr.2017
SCC in Boiler Steam Drum
M - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Macrography of a transverse section of the steam drum sample that was removed after the inspection had detected multiple cracks propagating into the thickness, more than 50% deep in the thickness.
190
VIEW
ML00018 / Apr.2017
SCC in Boiler Steam Drum
M - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - NItal Etched MacroDf - Transverse Section
Micrography of the crack at the internal surface of the steam drum. The shell plate presents a ferritic perlitic structure.
162
VIEW
ML00018 / Apr.2017
SCC in Boiler Steam Drum
M - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Branched Cracks
Micrography of a crack, in a sample as polished, presenting the opened crack.
144
VIEW
ML00018 / Apr.2017
SCC in Boiler Steam Drum
M - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Micrography by OMDf - Branched Cracks
Stress corrosion cracks propagating in the ferritic-perlitic structure.
120
VIEW
ML00018 / Apr.2017
SCC in Boiler Steam Drum
M - Low Carbon SteelP - Rolled PlateAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Branched Cracks

+3 more from this case →

ML00020 — Intergranular SCC in Boiler Steam Drum RepairM - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Aspect of the drum shell after removing the tubes and macroetching, indicating that the cracks were located in repair welded regions.
342
VIEW
ML00020 / Apr.2017
Intergranular SCC in Boiler Steam Drum Repair
M - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Cm - Aspect by NDTDf - Cracks
A small sample was removed from the steam drum and the micrography shows that the cracks are intergranular (previous austenite) and located in the weld metal.
285
VIEW
ML00020 / Apr.2017
Intergranular SCC in Boiler Steam Drum Repair
M - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Corrosion Cracking
The micrography of the small sample removed from the steam drum shows that the cracks are intergranular (previous austenite) and located in the weld metal.
274
VIEW
ML00020 / Apr.2017
Intergranular SCC in Boiler Steam Drum Repair
M - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Corrosion Cracking
Secondary cracks in the weld metal showing an intergranular morphology. Stress Corrosion Cracking.
249
VIEW
ML00020 / Apr.2017
Intergranular SCC in Boiler Steam Drum Repair
M - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Corrosion Cracking
Detail of the secondary cracks in the weld metal with intergranular morphology. Stress Corrosion Cracking.
251
VIEW
ML00020 / Apr.2017
Intergranular SCC in Boiler Steam Drum Repair
M - Low Carbon SteelP - Repair WeldAp - BoilerCd - Stress Corrosion
Cm - Nital Etched Micrography by OMDf - Corrosion Cracking

+1 more from this case →

ML00008 — Cold Cracks in CMn Steel Pressure VesselM - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Micrography of a longitudinal section of the shell plate base metal, presenting a typical ferritic-perlitic microstructure.
149
VIEW
ML00008 / Nov.2017
Cold Cracks in CMn Steel Pressure Vessel
M - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Higher magnification of the ferritic-perlitic microstructure of the shell plate in the longitudinal section.
129
VIEW
ML00008 / Nov.2017
Cold Cracks in CMn Steel Pressure Vessel
M - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Cold cracking of the fillet weld adopted to attach a flat support into a vessel shell in the internal side, using an unsuitable welding procedure that created a too high hardness HAZ.
123
VIEW
ML00008 / Nov.2017
Cold Cracks in CMn Steel Pressure Vessel
M - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks
Cold cracking of the fillet weld adopted to attach a flat support into a vessel shell in the internal side, using an unsuitable welding procedure that created a too high hardness HAZ. The cracks are mainly located at the fusion line.
118
VIEW
ML00008 / Nov.2017
Cold Cracks in CMn Steel Pressure Vessel
M - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks
Cold cracking of the fillet weld adopted to attach a flat support into a vessel shell in the internal side, using an unsuitable welding procedure that created a too high hardness HAZ. Several internal cracks at the fusion line.
101
VIEW
ML00008 / Nov.2017
Cold Cracks in CMn Steel Pressure Vessel
M - CMn SteelP - In Field WeldAp - BoilerCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracks

+2 more from this case →