Low Carbon Steel

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Crevice Corrosion in a Subsea System — Aspect Before Analysis

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Aspect before cleaning of the heavy U bolt pipe clamp, 38 mm diameter wire, at the fractured position. It is possible to see that it broke in a region where the clamp was no longer coated and there is no insert in the groove (at the internal clamp diameter). The fracture is transverse to the clamp axis.
522
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - General View
Gas piping. Aspect of a branching line 2" ND, lateral to a horizontal main pipe ND 8", welded using a weldolet. The cracking started at the margin of the weld in the upper part of the pipe, where the weld crossed the longitudinal direction of the pipe, perpendicular to the branch.
932
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Cracking
Scanning electron microscopy image of the chromium plated cylinder surface, presenting deposits and localized dissolution under deposits. There are different stages of corrosion in this region, observed in low magnification. Small areas of attack and a shallow pitting with deposits that were analyzed by EDS and revealed the presence of S.
903
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Surface Aspect by SEMDf - Localized Corrosion
Detailed aspect of the eye bolt fracture position, with strong plastic deformation indicating ductile overloading. The red marks in the thread surface of the bolt (in the left side of the image) correspond to the position where the nut was tight. Thread fillets adjacent to the fracture presented secondary cracks.
1125
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Aspect Before AnalysisDf - Ductile Fracture
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
The hose connector fracture surface presented different fracture micromechanisms associated to the microstructure: inclusion decohesion, small regions of intergranular fractures (probably due to cementite at grain boundaries), and cleavage of the ferritic structure. All these mechanisms are brittle.
560
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Fractography by SEMDf - Brittle Fracture
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

More from these cases

ML00171 — Corrosion Fatigue of U Bolt Pipe ClampM - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Aspect of the U bolt clamp with partial detachment of the coating (white brown) in a region where the polimeric insert (dirty white) is still in the wire groove at the internal clamp diameter (ID).
91
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - General View
Detailed aspect of the fractured position, in a region where the clamp was no longer coated and there is no insert in the groove (at the internal clamp diameter). The fracture is transverse to the clamp axis.
86
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
Same aspect of the previous image after cleaning, showing a subcritical propagation aspect (fatigue), starting at the groove (ID) and also at the clamp surface in the OD.
75
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
In the region where the polimeric insert was loose, the protective coating of the clamp has suffered detachment.
69
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Layer Detachment
Close to the ID of the clamp, at the groove position, there are cracks in the coating (white brown) and also at the substrate.
63
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Cracks

+22 more from this case →

ML00149 — Vibration Induced Fatigue in a Gas PipingM - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Gas piping. Aspect of a branching line 2" ND with a flange, lateral to a main pipe ND 8", welded using a weldolet. The cracking is at the margin of the weld.
115
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - General View
Micrography of a transverse section of the seamless pipe, presenting a ferritic-pearlitic structure.
84
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrography of a transverse section of the seamless pipe, presenting a ferritic-pearlitic structure.
70
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Gas piping. Aspect of a branching line 2" ND, lateral to a horizontal main pipe ND 8", welded using a weldolet. In the lower part of the branch there are no cracks.
61
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Welded Joint
Aspect of the brach line viewed from the internal side of the main pipe, after cuting. It is possible to see that the pipe was perforated by a thermal cutting (looking the finishing aspect of the edge of the hole). The weldolet was welded only from the external side of the pipe.
62
VIEW
ML00149 / Dec.2018
Vibration Induced Fatigue in a Gas Piping
M - Low Carbon SteelP - Piping spoolAp - FPSOCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Internal Surface

+13 more from this case →

ML00128 — MIC of a Stored Hydraulic CylinderM - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Aspect of the hydraulic cylinder, new, stored in tropical conditions under a plastic cover, that allowed a condensation condition and damage.
92
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - General View
Aspect of the hydraulic cylinder surface presenting white stains in a region where the damage was still in the begining.
73
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - External Surface
Aspect of the hydraulic cylinder surface presenting white stains and black oxides in a region that started a localized dissolution under deposit.
72
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - Corrosion
Detail of the cylinder external surface, with deep dissolution as the worst damage morphology.
65
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - Corrosion
As polished micrographic aspect of the longitudinal section of the cylinder, at the surface, in a region where the damage is in the begining. It is possible to see that there are two layers at the surface. A first Ni layer, 300HV average hardness, over the low carbon steel substrate, 200HV average hardness, and a chromium plated layer, 1100HV average hardness and several discontinuities.
62
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Micrography by OMDf - Longitudinal Section

+12 more from this case →

ML00120 — Ductile Rupture of a Carbon Steel Eye BoltM - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Macrography of a longitudinal section of the eye bolt, presenting the fracture in the top of the figure and the threads in the left side of the figure. Details of the fracture of the first thread fillet below the fracture are presented in the next figures.
225
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - NItal Etched MacroDf - Longitudinal Section
Micrography as polished of the longitudinal section of the bolt at the fracture position. The fracture (top of the figure) is rough, characteristic of a ductile fracture.
196
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - As polished micrographyDf - Fracture
Micrography as polished of the longitudinal section of the bolt at the first thread fillet below the fracture, presenting a cracking at the bottom of the fillet.
194
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - NItal Etched MacroDf - Crack
Apect of the 1/2" ND bumper eye bolt that was fractured (in the left side of the figure) in the position where the nut was tight.
192
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Aspect Before AnalysisDf - General View
Micrography of a longitudinal section of the bolt in the center of the thickness, presenting a ferritic pearlitic structure with elongated grains due to the forming process, without later heat treatment.
173
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite

+5 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.
137
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 →

ML00103 — Brittle Fracture of a Free-Cutting ConnectorM - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Aspect of the external side of the connector, with a longitudinally crack of a brittle aspect. It is a 5/8" connector (15.8 mm).
134
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - General View
Aspect of the internal side of the connector. The fracture, in the longitudinal direction, presents a brittle aspect. The thickness of the connector is about 2 mm.
126
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Brittle Fracture
Macroscopic detail of the brittle fracture, in the longitudinal direction.
105
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Brittle Fracture
Micrography of the longitudinal section of the fitiing, in a free-cutting steel. The microstructure is predominantly ferritic and there is a large amount of sulfide inclusions, aligned perpendicular to the forming direction.
98
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of the longitudinal section of the fitiing, in a free-cutting steel. The microstructure is predominantly ferritic, with small perlitic areas and some free cementite at ferritic grain boundaries. There is a large amount of sulfide inclusions, aligned perpendicular to the forming direction.
107
VIEW
ML00103 / Nov.2017
Brittle Fracture of a Free-Cutting Connector
M - Low Carbon SteelP - Machined PartAp - ShipCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Non Metallic Inclusions

+11 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 →