Offshore

11 cases · 69 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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The location of the threaded fitting started leaking after less than five years in service. Although the corrosion rate was not high, the localized material loss in the threaded surface of the carbon steel flange allowed the connection leakage.
769
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - General View
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
Micrography of a longitudinal section of a 4 mm diameter wire base metal, presenting a strain hardened and aligned pearlitic structure.
42
VIEW
ML00113 / Jan.2018
Autogenous Weld of a Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Cm - Nital Etched Micrography by OMDf - Base Metal
Aspect of the 5/8" diameter pin, that was 3" long and broke close to the center.
104
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 - General View
Macrography of the fillet welded joint between the 3" ND tube and the 3/4" thick plate. See the schematic drawing in the next figure
56
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 - Welded Joint
General view of the 2" branch line that was supporting an instrument in a 12" gas piping of an offshore unity. The branch line is composed by a seamless pipe welded to a weldolet (left side of the figure) and to a flange (right side of the figure). The leakage is associated to a through wall cracking in the middle of the pipe length. The cracking is not evidenced in the figure, since it is too thin. See the schematic drawing in the next figure
494
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 - General View
Macrography of the welded joint upper part. Transverse section showing the different zones studied in this ML. See the schematic drawing in the next image.
454
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Kalling Etched MacroDf - Welded Joint
Fracture appearance of the 1 1/4" diameter link. The fracture is flat and presented no evidences of plastic deformation, suggesting a brittle behavior.
54
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View

More from these cases

ML00184 — Dissimilar Steels in a Threaded ConnectionM - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
The cleaned fitting is sound. No corrosion, only surface stains.
121
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Aspect After CleaningDf - General View
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
ML00128 — MIC of a Stored Hydraulic CylinderM - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
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
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
Detail of a localized dissolution at the surface of the chromium plated cylinder. Note the dimension of the corrosion pitting, shallow.
33
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - At the Surface
Scanning electron microscopy image of the chromium plated surface in a position where the cylinder was not damaged, showing the surface finishing.
35
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Surface Aspect by SEMDf - At the Surface
ML00113 — Autogenous Weld of a Carbon Steel WireM - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Low magnification micrography of a longitudinal section of a 4 mm diameter base metal wire, presenting a strain hardened and aligned pearlitic structure.
32
VIEW
ML00113 / Jan.2018
Autogenous Weld of a Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Cm - Nital Etched Micrography by OMDf - Base Metal
Macrography of a longitudinal section of a 4 mm diameter wire, presenting part of an austogenously welded joint, with the transformation of the strain hardened pearlitic. The base metal is to the left side of the figure, and the heat affected zone is in the center of the figure. There is a (previous austenite) grain growth to the right side of the figure, where it is the center of the weld.
33
VIEW
ML00113 / Jan.2018
Autogenous Weld of a Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Cm - NItal Etched MacroDf - Welded Joint
Low magnification micrography of a longitudinal section of a 4 mm diameter wire, at the region where the pearlitic strain hardened wire is affected by the welding. The base metal is to the left side and the region of the HAZ that starts with a grain growth is to the right side.
24
VIEW
ML00113 / Jan.2018
Autogenous Weld of a Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone
Micrography of a longitudinal section of a 4 mm diameter wire, at the heat affected zone created by the autogenous welding, presenting a tempered martensitic structure.
19
VIEW
ML00113 / Jan.2018
Autogenous Weld of a Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone
Micrography of a longitudinal section of a 4 mm diameter wire, in the center of the autogenously welded joint, presenting the alignment of the structure (left side of the figure) changing its direction due to the pressure between the parts during the welding. In the center of the weld (right side of the figure) there is a grain growth of the previous austenite structure.
23
VIEW
ML00113 / Jan.2018
Autogenous Weld of a Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Welding
Cm - Nital Etched Micrography by OMDf - In the Center of the Weld

+1 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 position of the cracking, at the margin of the weld in the tube and underbead.
47
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 - Welded Joint
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
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

+6 more from this case →

ML00012 — Vibration Induced Fatigue in a 316/316L SSM - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Schematic drawing presenting the general view of the 2" branch line that was supporting an instrument in a 12" gas piping of an offshore unity.
94
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Identification drawingDf - General View
Aspect of the internal surface of the pipe after longitudinal cutting, presenting a straight cracking, circumferential. The weldolet is to the left side and the flange is to the right side. See the schematic drawing in the next figure.
89
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 - Internal Surface
Schematic drawing presenting the cracking surface aspect.
71
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Identification drawingDf - Internal Surface
Circumferential cracking in the middle of the pipe, view from the external side. Several pits close to the cracking.
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 - External Surface
Pipe view from the external side. Pitting corrosion.
42
VIEW
ML00012 / Aug.2017
Vibration Induced Fatigue in a 316/316L SS
M - Austenitic Stainless SteelP - Seamless PipeAp - OffshoreCd - Vibration Induced Fatigue
Cm - Surface Aspect by SEMDf - External Surface
ML00045 — Subsea Tubular F6NM Martensitic SSM - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Schematic drawing presenting the different zones of the welded joint at the upper part.
49
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Identification drawingDf - Welded Joint
Macrography of the welded joint, at the root position, presenting the different zones studied in this ML. Transverse section. See the schematic drawing in the next image.
47
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Kalling Etched MacroDf - Welded Joint
Schematic drawing presenting the different zones of the welded joint
35
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Identification drawingDf - Welded Joint
Base metal micrographic detail presenting a tempered martensitic microstructure.
27
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Kalling Etched Micrography by OMDf - Base Metal
Micrographic detail of the heat-affected zone close to the base metal.
29
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Kalling Etched Micrography by OMDf - Heat Affected Zone

+15 more from this case →

ML00079 — Hydrogen Cracking of a Maritime Chain LinkM - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Macrography of the longitudinal section of the broken link, at the fracture surface. There are several secondary cracks, parallel and perpendicular to the link axis.
37
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Longitudinal Section AspectDf - Longitudinal Section