Preferential Dissolution

3 cases · 10 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Capture method: Transverse Section Aspect clear all

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Macrography of a transverse section of the tube close to the leakage point, evidencing a localized thinning from the internal side of the tube.
65
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Localized Thinning
Detail of the transverse section of the 4" pipe at the longitudinal seam weld evidencing the leakage position. The damage appears as a through wall opening. The pipe thickness is 8 mm and there are no evidences of general corrosion (the SCH 80 corresponds to 8.6 mm) or pitting at the internal surface.
100
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 - Leakage
Transverse section of the tubesheet, after removal of the tubes. The seawater sie is to the top of the figure. It is possible to see regions of localized corrosion close to the tube position and a red layer all through the plate surface.
182
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Corrosion

More from these cases

ML00170 — MIC in Aluminum Brass TubesM - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Macrograhy of
5
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Localized Thinning
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 90° from the seam weld. The thickness of the pipe is 8 mm. No evidences of general corrosion or pitting were identified.
77
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 - Transverse Section
Detail of the transverse section of the 4" pipe 90° from the seam weld. The thickness of the pipe is 8 mm. No evidences of general corrosion or pitting were identified.
70
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 - Transverse Section
Detail of the transverse section of the 4" pipe 180° from the seam weld. The thickness of the pipe is 8 mm. No evidences of general corrosion or pitting were identified.
64
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 - Transverse Section
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
ML00125 — Dezincification of a Cooler TubesheetM - BrassP - PlateAp - ShipCd - Preferential Dissolution
Macrographic detail of the transverse section of the tubesheet at the cooper alloy tube position, after removal of the 5/8" tube. The red layer at the top of the plate (exposed to the cooling medium - treated seawater) is a region of selective corrosion, dezincification.
169
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Corrosion
Macrographic detail of the transverse section of the tubesheet at the cooper alloy tube position, after removal of the 5/8" tube. The "layer" at the top of the plate (exposed to the cooling medium - treated seawater) is a region of selective corrosion, dezincification. It is possible to see that in the right side of the figure, where the cooper tube was positioned, the corrosion damage is deeper.
153
VIEW
ML00125 / Mar.2018
Dezincification of a Cooler Tubesheet
M - BrassP - PlateAp - ShipCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Dezincification