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Crevice Corrosion in a Subsea System — Aspect Before Analysis

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Internal surface detail of the 3 1/2" pipe, cut in a longitudinal section (transverse to the weld), presenting a localized corrosion at the margin of the welded joint (Keller etched), in the root. The pipeline was assembled with pipes manufactured in two different aluminum alloys, AA 3003 (top of the figure) and AA 6063 (bottom of the figure), and the localized corrosion occurred at the fusion line of the 6063 pipe.
1296
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Surface AspectDf - Welded Joint
Micrography of the nut in the longitudinal direction, in the center of the thickness, presenting a granular austenitic structure free from detrimental phases.
475
VIEW
ML00062 / Apr.2017
Inconel 718 Lock Nut with Polymer Insert
M - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - In the Center of the Thickness
Macroscopic aspect of the 1" shaft fracture surface, revealing beach marks at the surface typical of fatigue, initiated from the surface of the spline shaft at the gear position.
498
VIEW
ML00041 / Jun.2017
Fatigue Fracture of Inconel 718 Spline Shaft
M - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Fatigue Fracture
Internal aspect of the 8" diameter pipe that suffered localized thinning and leakage. The vertical weld is the pipe seam and the horizontal weld is the circunferential butt weld.
564
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Aspect Before AnalysisDf - Localized Thinning
Transverse section of the fitting that suffered a longitudinal cracking. As polished. The wrought fitting has suffered intergranular stress corrosion cracking from the internal surface, exposed to hot caustic environment.
566
VIEW
ML00011 / Oct.2017
Intergranular SCC of Pure Nickel
M - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
Cm - Micrography by OMDf - Intergranular Cracking

More from these cases

ML00059 — Intergranular Corrosion of Aluminum PipingM - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
The macrography of the welded joint shows the AA 6063 alloy pipe in the right and the AA 3003 pipe in the left, welded in two passes. The root presents small regions of corrosion in the weld metal and a localized corrosion at the fusion line of the 6063 pipe (knife-line attack morphology).
397
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched MacroDf - Localized Corrosion
Micrography of a longitudinal section of the pipe AA 3003. Granular structure that reveals the forming direction and dispersed particles.
229
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Base Metal Left Side
Micrographic detail of a longitudinal section of the pipe AA 3003. Granular structure and dispersed particles.
199
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Base Metal Left Side
Micrography of a longitudinal section of the pipe AA 6063. Granular structure and dispersed particles.
169
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Base Metal Right Side
Micrographic detail of a longitudinal section of the pipe AA 6063. Granular structure and dispersed particles.
138
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched MacroDf - Base Metal Right Side

+12 more from this case →

ML00062 — Inconel 718 Lock Nut with Polymer InsertM - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
The nut was sectioned in the longitudinal direction to reveal the position of the Nylon insert.
59
VIEW
ML00062 / Apr.2017
Inconel 718 Lock Nut with Polymer Insert
M - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - Transverse Section
Micrography of the nut in the longitudinal direction, at the thread, presenting a granular austenitic structure free from detrimental phases or cold forming effects.
56
VIEW
ML00062 / Apr.2017
Inconel 718 Lock Nut with Polymer Insert
M - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
Micrographic detail of the nut at the thread, presenting a granular austenitic structure free from cold forming effects.
52
VIEW
ML00062 / Apr.2017
Inconel 718 Lock Nut with Polymer Insert
M - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
Micrography of the nut in the longitudinal direction, at the Nylon insert position, showing a cold formed region at the end of the nut, with high hardness levels (about 600 HV100g).
53
VIEW
ML00062 / Apr.2017
Inconel 718 Lock Nut with Polymer Insert
M - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Strain Hardened
Micrographic detail of the nut at the cold formed region where the nut was bent over the Nylon insert. It is possible to see strain hardened structures (600HV 100g).
41
VIEW
ML00062 / Apr.2017
Inconel 718 Lock Nut with Polymer Insert
M - NiCrFe AlloyP - Cold FormedAp - PipingCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Strain Hardened
ML00041 — Fatigue Fracture of Inconel 718 Spline ShaftM - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
xx
117
VIEW
ML00041 / Jun.2017
Fatigue Fracture of Inconel 718 Spline Shaft
M - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - At the Surface
Macroscopic aspect of the 1" shaft fracture surface, revealing beach marks at the surface typical of fatigue, initiated from the surface of the spline shaft at the gear position.
121
VIEW
ML00041 / Jun.2017
Fatigue Fracture of Inconel 718 Spline Shaft
M - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Fatigue Fracture
SEM fractograph at 1200x magnification showing an intergranular fracture surface with angular, faceted grains and fine feather-like markings.
86
VIEW
ML00041 / Jun.2017
Fatigue Fracture of Inconel 718 Spline Shaft
M - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
Cm - Fractography by SEMDf - Fatigue Fracture
Microscopic detail of the transgranular striation in the fracture surface.
78
VIEW
ML00041 / Jun.2017
Fatigue Fracture of Inconel 718 Spline Shaft
M - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
Cm - Fractography by SEMDf - Fatigue Fracture
The micrography of a transverse section of the shaft shows the granular austenitic structure close to the surface of the shaft.
67
VIEW
ML00041 / Jun.2017
Fatigue Fracture of Inconel 718 Spline Shaft
M - NiCrFe AlloyP - ShaftAp - Oil and GasCd - Vibration Induced Fatigue
Cm - Kalling Etched Micrography by OMDf - At the Surface

+7 more from this case →

ML00005 — Environmental Hydrogen Damage in Ti PipeM - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
External aspect of the 8" diameter pipe that suffered localized thinning and leakage associated to the welded regions. The vertical weld is the pipe seam and the horizontal weld is the circunferential butt weld.
142
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Aspect Before AnalysisDf - Welded Joint
Aspect of the internal surface of the pipe at the welded region, showing the interface of the thinning area in the weld and the pipe base metal.
128
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Surface Aspect by SEMDf - Localized Thinning
Region of the localized thinning at the weld metal, in a metallographic section, as polished. In the base metal the hydride layer is continuous and no thinning is evident (left side of the figure) and in the weld metal it is detached and cracked (right side of the figure).
107
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Micrography by SEMDf - Localized Thinning
The microstructure of the pipe base metal, in the center of the thickness, is granular alpha.
102
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Granular structure
The pipe base metal, at the internal surface, presents a hydride layer showing that the environment is absorbing hydrogen. Although there are microcracks in this layer it did not detach in the base metal.
102
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Hydride Formation

+6 more from this case →

ML00011 — Intergranular SCC of Pure NickelM - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
The fitting presented through wall cracks that lead to leaking. The internal aspect of the surface is presented where the cracks were still in the begining.
127
VIEW
ML00011 / Oct.2017
Intergranular SCC of Pure Nickel
M - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
Cm - Aspect Before AnalysisDf - Crack
Microstructure of the fitting in the transverse section, presenting a granular Ni austenitic structure. No evidences of any phase in the grain boundaries.
113
VIEW
ML00011 / Oct.2017
Intergranular SCC of Pure Nickel
M - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
Cm - Kalling Etched Micrography by OMDf - Austenite
Microstructure of the fitting in the transverse section, presenting a granular Ni austenitic structure. No evidences of any phase in the grain boundaries.
110
VIEW
ML00011 / Oct.2017
Intergranular SCC of Pure Nickel
M - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
Cm - Kalling Etched Micrography by OMDf - Austenite
Microstructure of the fitting in the transverse section, presenting a granular Ni austenitic structure. No evidences of any phase in the grain boundaries.
96
VIEW
ML00011 / Oct.2017
Intergranular SCC of Pure Nickel
M - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
Cm - Kalling Etched Micrography by OMDf - Austenite
After opening the crack the fracture surface presented different aspects close to the internal surface and through the wall propagation. Intergranular at the surface, showing intergranular SCC mechanism, and transgranular with striation, showing the contribution of pulsing loads.
101
VIEW
ML00011 / Oct.2017
Intergranular SCC of Pure Nickel
M - Unalloyed NickelP - Wrought FittingAp - Chemical IndustryCd - Stress Corrosion
Cm - Fractography by SEMDf - Through Wall Cracking

+7 more from this case →