Offshore

10 cases · 75 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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The painting of the valve body was detaching at the vent location where the fitting was installed, not fully tighted. Three threaded fillets were outside of the body.
190
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Aspect After CleaningDf - Painting Detachment
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
Microscopic detail of the cracks at the surface of the pin, close to the fracture. It is possible to see that the cracks are not associated to plastic deformation at the surface. Instead they are brittle and associated to regions where the material lost the passivation (dark grey stains at the surface). Some cracks that already opened (a little) showed deformation at the tips.
1024
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Surface Aspect by SEMDf - Multiple cracks
Aspect of the internal surface of the 2" nominal diameter pipe, SCH 40, presenting a circumferential through wall cracking in the pipe, not associated to any of the welded joints. It is possible to see the cracking parallel to the two welded joints: the pipe to weldolet (left side of the figure); and the pipe to flange (right side of the figure).
64
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Through Wall Cracking
Macrography showing the different regions of a pipe-to-plate fillet weld. See the schematic drawing in the next image
954
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - NItal Etched MacroDf - Fracture
Micrography of the longitudinal section of the link, presenting secondary cracks in the longitudinal direction, following segregation bands in the material.
541
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Secondary Cracks
The repair weld presented several cracks in the weld metal, transverse to the weld, detected during inspection using magnetic particle test. The cracks were mainly located in regions of the structure where the repair was conducted by welding in the vertical position using 1/8" stick electrode.
710
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Aspect by NDTDf - Cracking
Micrography as polished of the region where there was a refrigeration hole, presenting a cracking.
35
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - Micrography by OMDf - Cracking

More from these cases

ML00184 — Dissimilar Steels in a Threaded ConnectionM - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
The austenitic stainless steel fitting was removed from the valve body and presented the sdhesion of oily deposits.
150
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - Surface Deposits
The threads of the carbon steel valve body is corroded. The offshore ambient is wet and chloride rich, creating an aggressive environment for the carbon steel threads.
99
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Surface AspectDf - Corrosion
Not only the threads were corroded but all regions under the painting that was detached from the surface.
86
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Surface AspectDf - Corrosion
Macrosection of the valve body at the thread, showing the position where the fitting was installed.
84
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Transverse Section AspectDf - Corrosion
Macrosection detail of the valve body at the thread, showing the metal to metal contact between the carbon steel female thread and the stainless steel male thread.
80
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Transverse Section AspectDf - Localized Corrosion

+4 more from this case →

ML00128 — MIC of a Stored Hydraulic CylinderM - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
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
Micrographic aspect of the Cr layer at the surface presenting incipient damage. Microcracks of the Cr layer, associated to small pits.
62
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Micrography by OMDf - Cracks
Micrographic aspect, after Nital etching, of the longitudinal section of the cylinder, at the surface, in a region where the damage is in the begining. There are two layers at the surface. A first Ni layer, 160 microns thick and 300HV average hardness, over the low carbon steel substrate, 200HV average hardness, and a chromium plated layer, 250 microns thick and 1100HV average hardness.
59
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corrosion
Micrographic detail of the longitudinal section of the cylinder, at the surface, in a region where the Cr layer is detaching.
56
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corrosion

+2 more from this case →

ML00085 — Corrosion Fatigue of a Martensitic SS PinM - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Low magnification microscopy (stereoscope) detail of the multiple cracks at the pin surface.
146
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Surface AspectDf - Multiple cracks
Aspect of the pin surface, presenting multiple cracks, paralel to the fracture position.
122
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Multiple cracks
Typical fatigue fracture, reversed bending.
74
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
The fractographic analysis of the pin showed fatigue striation at the subcritical propagation region.
75
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Fractography by SEMDf - Fatigue Striation
The fractographic analysis of the pin showed ductile final fracture, by dimples.
76
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Fractography by SEMDf - Dimples

+9 more from this case →

ML00012 — Vibration Induced Fatigue in a 316/316L SSM - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Aspect of the internal surface of the 2" nominal diameter pipe, SCH 40, presenting a circumferential through wall cracking in the pipe, not associated to any of the welded joints. It is possible to see the cracking parallel to the two welded joints: the pipe to weldolet (left side of the figure); and the pipe to flange (right side of the figure).
57
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Through Wall Cracking
After opening the cracking the fracture surface aspect evidences fatigue cracking propagation, starting from the external side (OD).
68
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Fracture Surface AspectDf - Fatigue Fracture
Micrography of a longitudinal section of the pipe (seamless), that shows the through wall cracking, straigth and not associated to any welded region or microstructural problem.
64
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Micrography by OM using A262 Method ADf - Through Wall Cracking
Micrography of the pipe in a longitudinal section, close to the external surface, showing a pit (adjacent to the through wall cracking). The corrosion spt is not associated to any microstructural feature.
61
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Micrography by OMDf - Pitting
Aspect of a micrographic sample by scanning electron microscopy showing the external pipe surface, in the bottom, the fracture at the left side of the figure and several spots of pitting corrosion from the external surface. The polished section (transverse to the fracture and in a longitudinal section of the pipe) shows the morphology of the pit , 0.2 mm depth. Original magnification 50x.
54
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Micrography by SEMDf - Pitting

+6 more from this case →

ML00052 — Cold Cracks in API 5CT L80 Tube Welded to a Structural PartM - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Schematic drawing presenting the different regions of a pipe-to-plate fillet weld.
71
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Identification drawingDf - Fracture
The micrography shows the region underbead, of the tube HAZ, responsible for the hydrogen cracking (fracture in the right side of the photo - black). The hardness of the HAZ is about 600 HV.
55
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracking
ML00079 — Hydrogen Cracking of a Maritime Chain LinkM - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Micrographic detail of the longitudinal section of the link, presenting internal cracks of intergranular morphology, typical of a hydrogen assisted mechanism.
52
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
Micrography of the longitudinal section of the link, close to the fracture surface (in the top of the figure). There are secondary cracks parallel to the fracture.
33
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Secondary Cracks
Micrographic detail of the longitudinal section of the link, close to the fracture surface, presenting the intergranular morphology of the secondary cracks, parallel to the fracture.
29
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
Micrographic detail of the intergranular secondary cracks, parallel to the fracture, typical of a hydrogen assisted cracking.
29
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Intergranular Cracking
Micrographic detail of the intergranular secondary cracks, parallel to the fracture, typical of a hydrogen assisted cracking. Close to the cracking it is possible to see an elongated inclusion, probably of a sulfide type.
26
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Micrography by SEMDf - Intergranular Cracking
ML00010 — Cold Cracks in a Gouged Weld MetalM - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
After grinding to remove the cracks, it was possible to see that they originated in the root, with longitudinal and transverse cracking, and localized in the weld metal only.
167
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Aspect by NDTDf - Cracking
Acetate metallographic replica from the surface, before cracking removal, showing the intergranular morphology of the cracks in a very refined weld metal structure.
123
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital etched, OMDf - Intergranular Cracking
Detail of the acetate metallographic replica from the surface, before cracking removal, showing the (previous austenite) intergranular morphology of the cracks in a very refined weld metal structure.
107
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital etched, OMDf - Intergranular Cracking
Low magnification micrography of the weld metal, evidencing regions of low dilution of the entrapped carbon from the arc gouging.
61
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Hard Spots
Detail of a region of entrapped carbon from the arc gouging, in the weld metal.
55
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Hard Spots

+3 more from this case →

ML00042 — Gas Turbine Blade IN 939, CoatedM - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
The cracking from the refrigeration hole presents an intergranular morphology, as shown in the micrography of a transverse section of the blade.
35
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Intergranular Cracking