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Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Granular Standard: B clear all

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Micrographic detail of the austenitic structure at the surface, where the grain size of the material increased. By optical microscopy the intragranular precipitation due to solution annealing and aging is not revealed.
794
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Austenite
Region of the leakage close to the welded joint between the pipe and the 90° elbow, in the 1 1/2" nominal diameter piping, SCH 40 (3.7 mm thick). See the schematic drawing in the next figure
966
VIEW
ML00065 / May.2017
Erosion Corrosion of Monel Piping
M - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Cm - Aspect Before AnalysisDf - Leakage
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

ML00089 — Inconel 718 Allen Bolt for Subsea ApplicationM - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
The macrography shows the longitudinal section of the allen bolt, 1/2" nominal diameter, that was machined from a heat treated bar (solution annealed and aged). The granular structure presents differences in the grain sizes. At the bolt head (external surface of the original bar) the austenitic grain size is larger than in the center of the bar where the particles in segregated bands "arrested" the grains during hot forming and solution annealing.
58
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Machined Thread
The micrography of a longitudinal section of the bolt close to the surface, at the thread, shows that it was machined from a bar, not rolled.
37
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Machined Thread
The micrography of a longitudinal section of the bolt, in the center of the thickness (ND 1/2"), shows an equiaxial granular structure. Although the material was hardened by heat treatment (solution annealing and aging), the microstructure at this magnification does not reveal the intragranular precipitation.
34
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched Micrography by OMDf - Equiaxial Grains
Micrographic detail of a longitudinal section of the bolt, in the center of the thickness (ND 1/2"). Although the material was hardened by heat treatment (solution annealing and aging), the microstructure observed by optical microscopy does not reveal the intragranular precipitation.
33
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Austenite
The micrography of a longitudinal section, at the bolt head close to the surface of the original bar. In this region the material increased the grain size due to the lack of particles (inclusions), to "arrest" the grain boundaries (during hot forming and solution annealing). The smaller grain size is located in the center of the bar, that concentrated the inclusions.
30
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Dual grain sizes

+1 more from this case →

ML00065 — Erosion Corrosion of Monel PipingM - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Schematic drawing presenting the External piping surface
339
VIEW
ML00065 / May.2017
Erosion Corrosion of Monel Piping
M - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Cm - Identification drawingDf - Leakage
Aspect of the piping cut in the longitudinal direction, presenting the leakage region close to the welded joint between the pipe and the 90° elbow. The original SCH 40 (3.7 mm thickness) presents an actual average thickness of 2 mm all through the piping extension, evidencing a general thinning. See the schematic drawing in the next figure.
364
VIEW
ML00065 / May.2017
Erosion Corrosion of Monel Piping
M - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Cm - Aspect Before AnalysisDf - Leakage
Schematic drawing presenting the internal piping surface
234
VIEW
ML00065 / May.2017
Erosion Corrosion of Monel Piping
M - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Cm - Identification drawingDf - Leakage
Detail of the internal piping surface, showing lack of deposits and a shinning surface, suggesting erosive conditions.
226
VIEW
ML00065 / May.2017
Erosion Corrosion of Monel Piping
M - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Cm - Surface AspectDf - Leakage
Macrography of the pipe to fitting welded joint, in a region where the thickness loss is almost uniform. The pipe is in the left of the figure and the elbow is in the right, with a general thinning (average of 2 mm, considering that the original thickness was 3.7 mm), and a slightly more intense thickness loss at the weld metal near the elbow side.
183
VIEW
ML00065 / May.2017
Erosion Corrosion of Monel Piping
M - NiCu AlloyP - Seamless PipeAp - Chemical IndustryCd - Erosion Corrosion
Cm - Kalling Etched MacroDf - Welded Joint

+18 more from this case →

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.
120
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 →