Localized Dissolution

2 cases · 32 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Results

SortNewestOldestTitle A-ZTitle Z-A
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
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

More from these cases

ML00184 — Dissimilar Steels in a Threaded ConnectionM - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
The painting of the valve body was detaching at the vent location where the fitting was installed, not fully tighted. Three threaded fillets were outside of the body.
190
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Aspect After CleaningDf - Painting Detachment
The austenitic stainless steel fitting was removed from the valve body and presented the sdhesion of oily deposits.
150
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - Surface Deposits
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
The threads of the carbon steel valve body is corroded. The offshore ambient is wet and chloride rich, creating an aggressive environment for the carbon steel threads.
99
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Surface AspectDf - Corrosion
Not only the threads were corroded but all regions under the painting that was detached from the surface.
86
VIEW
ML00184 / Apr.2023
Dissimilar Steels in a Threaded Connection
M - Low Carbon SteelP - ForgingAp - OffshoreCd - Localized Dissolution
Cm - Surface AspectDf - Corrosion

+8 more from this case →

ML00128 — MIC of a Stored Hydraulic CylinderM - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
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
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
Aspect of the hydraulic cylinder surface presenting white stains and black oxides in a region that started a localized dissolution under deposit.
72
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - Corrosion
Detail of the cylinder external surface, with deep dissolution as the worst damage morphology.
65
VIEW
ML00128 / Apr.2018
MIC of a Stored Hydraulic Cylinder
M - Low Carbon SteelP - Chromium PlatedAp - OffshoreCd - Localized Dissolution
Cm - Aspect Before AnalysisDf - Corrosion
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

+12 more from this case →