Offshore

10 cases · 69 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Damage Capture method: Optical Microscope clear all

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Micrography of the thread at the valve body surface, showing localized dissolution of the thread.
73
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corroded Thread
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
Micrography of the pin microstructure at the longitudinal section showing a tempered martensitic structure and a band of retained austenite.
61
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Kalling Etched Micrography by OMDf - Martensite
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
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
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
Tempered martensitic structure of the plate base metal.
93
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 - Base Metal
Transverse section of the blade showing large grains of this poliycristaline cast material.
421
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Coarse Structure

More from these cases

ML00184 — Dissimilar Steels in a Threaded ConnectionM - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Micrography of the valve body carbon steel thread, in the valley. Ferritic-bainitic structure.
77
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Transverse Section
Micrographic detail of the valve body carbon steel thread, in the valley. Ferritic-bainitic structure.
69
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Bainitic Ferrite
Micrography of the valve body carbon steel thread, in the peak. Ferritic-bainitic structure.
64
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corroded Thread
Micrographic detail of the valve body carbon steel thread, in the peak. Ferritic-bainitic structure.
55
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Corroded Thread
Cross-section near a threaded surface showing an acicular matrix structure bordered by a dark, layered corrosion/oxide band along the thread root.
1
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Nital Etched Micrography by OMDf - Oxide Layer
ML00128 — MIC of a Stored Hydraulic CylinderM - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
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
Micrographic aspect of the longitudinal section of the cylinder steel substrate, presenting a ferritic-pearlitic structure.
207
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 - Ferrite and Pearlite
Micrographic detail of the ferritic-pearlitic structure of the cylinder steel substrate.
41
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 - Ferrite and Pearlite

+3 more from this case →

ML00085 — Corrosion Fatigue of a Martensitic SS PinM - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Micrographic detail of the pin microstructure at the longitudinal section showing a tempered martensitic structure and a band of retained austenite.
62
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Kalling Etched Micrography by OMDf - Banded Structure
Micrographic detail of the pin microstructure at the longitudinal section showing a band of retained austenite in martensitic structure.
58
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Kalling Etched Micrography by OMDf - Martensite
Micrography of the pin in a longitudinal section, transverse to the fracture surface, close to the point of cracking iniciation, presenting a flat propagation and a secondary crack, paralel to the fracture surface.
54
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Kalling Etched Micrography by OMDf - Fracture
Micrography of the pin in a longitudinal section, transverse to the fracture surface, close to the point of cracking iniciation, presenting a flat propagation and a secondary crack, paralel to the fracture surface.
52
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Kalling Etched Micrography by OMDf - Fracture
Micrographic detail of a secondary cracking close to the fracture position. The crack presents no plastic deformation, is slightly branched and filled with products.
52
VIEW
ML00085 / Nov.2017
Corrosion Fatigue of a Martensitic SS Pin
M - Martensitic Stainless SteelP - Forged PinAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Kalling Etched Micrography by OMDf - Fatigue Fracture

+6 more from this case →

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 a longitudinal section of the link, presenting a tempered martensitic structure, typical of a quenching and tempering heat treatment and compatible with the link hardness of 43 HRc.
67
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 - Martensite
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
ML00012 — Vibration Induced Fatigue in a 316/316L SSM - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
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
Micrography of a longitudinal section of the pipe presenting a granular austenitic structure, typical of a solid solution annealing condition. No carbide precipitation.
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 OM using A262 Method ADf - Austenite
ML00052 — Cold Cracks in API 5CT L80 Tube Welded to a Structural PartM - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Low carbon plate base metal presenting the ferritic perlitic structure.
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 - Base Metal
High Strenght Low Alloy steel tube, base metal, presenting the bainitic structure.
54
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 - Base Metal
Micrography of the low carbon steel plate at the fusion line, presenting a bainitic structure at the HAZ and ferritic structure in the weld metal.
82
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 - Fusion Line
The micrography shows the martensitic region of the tube HAZ responsible for the hydrogen cracking, presenting too high hardness level (600 HV). It is a fresh martensite since the joint was welded in one pass and there was no PWHT.
45
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 - Martensite
Micrography of the weld metal in the center of the fillet showing a 100% acicular ferrite that is a microestructure of a high strenght steel, evidenced the effect of the dilution of the tube chemistry in the weld metal.
40
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 - Weld Metal

+1 more from this case →

ML00010 — Cold Cracks in a Gouged Weld MetalM - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Detail of the tempered martensitic structure of the plate base metal. Hardness level of 27 HRc.
92
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 - Base Metal
Low magnification micrography of a transverse section of the weld at the heat affected zone region. The macrosection was hardness tested and the base metal hardness is 27HRc, the HAZ is 32HRc and the weld metal is 45HRc, revealing something wrong in the weld metal at the position close to the cracked area.
79
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 - Transverse Section
High temperature heat affected zone of the plate, welded in repair. The micrography was taken from a sample collected close to the cracked region, but not containing any macroscopic cracking.
76
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 - Heat Affected Zone
Detail of the high temperature heat affected zone of the plate, welded in repair.
69
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 - Heat Affected Zone
The weld metal, hard, presented a martensitic structure, probably due to the localized increase in carbon content, from the unsuitable carbon arc gouging procedure.
63
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 - Weld Metal

+5 more from this case →

ML00042 — Gas Turbine Blade IN 939, CoatedM - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Micrography close to the surface of the blade, showing the diffusion coating (aluminum base alloy) that is still sound. No strong oxidation or erosion was detected.
53
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Coating
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
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