Localized Corrosion

8 cases · 23 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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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
Detailed aspect, by a low magnification microscope, of the internal side of the tube, after longitudinal cut. The tube, that is 1.6mm thick, presented several points of localized corrosion leading to leaks.
46
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface AspectDf - Localized Corrosion
Aspect of a transverse section of the 4" pipe showing the barnacles adhered to the internal pipe surface, and the leakage position (in the top of the figure). It is possible to see that the deposits are attached all throught the internal pipe perimeter but the damage is localized. The damage morphology suggests it is a crack, or a welding defect, but the microstructural analysis indicated that the damage is a galvanic effect at the autogenous seam weld.
1135
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Longitudinal Section AspectDf - Localized Corrosion
Aspect of the external side of the nominal diameter 6 3/4" drilling tool, after cleaning for inspection. Several regions of corrosion where detected where the drilling mud was adhered and remained for a period a little longer than 1 month. This tool is a high strength steel, cold worked.
125
VIEW
ML00135 / May.2018
MIC of a Non Magnetic Drilling Tool
M - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Cm - Aspect Before AnalysisDf - Localized Corrosion
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
Macroscopic aspect of the crack after cleaning the ring surface. Transverse cracks were identified associated to pitting corrosion.
44
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Localized 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
Regions of the pin thread presenting pitting corrosion.
635
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Surface Aspect by SEMDf - Localized Corrosion

More from these cases

ML00170 — MIC in Aluminum Brass TubesM - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
MIC in Aluminum Brass Tubes
2
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Localized Corrosion
ML00140 — Preferential Corrosion of Pipe Seam WeldM - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Detail of the transverse section of the 4" pipe at the longitudinal seam weld where it is not leaking yet, showing that the damage is not a crack but a localized dissolution, or localized corrosion or preferential dissolution at the autogenous seam weld. The thickness of the pipe is 8 mm and there are no evidences of general corrosion or pitting.
63
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Localized Corrosion
Micrography of the pipe in the leakage area, showing the preferential corrosion in the center of the autogenous weld and oxides inside the crevice, that appearas as a cracking but that is only a localized anodic process.
65
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Localized Corrosion
Micrographic detail of the autogenous seam weld. The localized dissolution occurrs exactly at the weld metal that presents a bainitic structure of average hardness about 230HV, compared to the heat affected zone presenting average of 202 HV and the base metal presenting average of 180HV.
56
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Localized Corrosion
Micrographic detail presenting the slighltly decarburized ferritic structure, with inclusions, in the center of the weld, surrounded by a bainitic structure and the preferential corrosion in the weld.
51
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - Nital Etched Micrography by OMDf - Localized Corrosion
Macrography of a transverse section of the pipe presenting localized dissolution at the longitudinal autogenous seam weld.
45
VIEW
ML00140 / May.2019
Preferential Corrosion of Pipe Seam Weld
M - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Cm - NItal Etched MacroDf - Localized Corrosion
ML00135 — MIC of a Non Magnetic Drilling ToolM - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Microscopical aspect by scanning electron microscopy (SEM) of the external surface of a drilling tool in a position that presented localized deposits and corrosion under deposit. It is possible to see that the strain hardened surface was etched by the aggressive metabolites of the microorganisms.
90
VIEW
ML00135 / May.2018
MIC of a Non Magnetic Drilling Tool
M - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Cm - Surface Aspect by SEMDf - Localized Corrosion
Micrographic detail of the damaged region close to the external surface, presenting a shallow localized dissolution/corrosion.
48
VIEW
ML00135 / May.2018
MIC of a Non Magnetic Drilling Tool
M - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Localized Corrosion
Micrography of the damaged region close to the internal surface, presenting a deep pitting corrosion morphology.
40
VIEW
ML00135 / May.2018
MIC of a Non Magnetic Drilling Tool
M - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Localized Corrosion
ML00059 — Intergranular Corrosion of Aluminum PipingM - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Intergranular corrosion at the fusion line of the AA 6063 pipe.
81
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Localized Corrosion
Intergranular corrosion at the fusion line of the AA 6063 pipe, that presents strong precipitation.
89
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Localized Corrosion
Micrographic detail of the intergranular corrosion at the fusion line of the AA 6063 pipe.
72
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Localized Corrosion
ML00016 — SCC in Free Cutting 303SSM - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
The macrography of the longitudinal section of the pin (9.5 mm nominal diameter) shows the localized corrosion associated to the non metallic inclusions.
107
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Localized Corrosion
The low magnification micrography of the longitudinal section of the pin shows the localized corrosion associated to the non metallic inclusions.
89
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Micrography by OM using A262 Method ADf - Localized Corrosion
The micrographic detail of the longitudinal section of the pin shows the localized corrosion associated to the non metallic inclusions.
67
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Micrography by OM using A262 Method ADf - Localized Corrosion