Preferential Dissolution

1 case · 5 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Product: Longitudinal Seam Welded Pipe clear all

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Macrography of a transverse section of the pipe, 8 mm thick, presenting localized dissolution at the longitudinal autogenous seam weld.
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 MacroDf - Preferential Dissolution

More from these cases

ML00140 — Preferential Corrosion of Pipe Seam WeldM - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Micrography of the pipe in the leakage area, at the internal pipe surface, showing the preferential corrosion in the center of the autogenous weld and oxides inside the crevice. The morphology of the corrosion is similar to a cracking but the analysis show that it is a localized anodic process.
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 Micrography by OMDf - Preferential Dissolution
Micrography of the pipe at the leakage position showing an oxide layer inside the crevice. The corrosion occurred exactly at the weld metal and the region at the margin of the damage shows the heat affected zone of the autogenous weld, with a refined grain size.
41
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 - Preferential Dissolution
Micrography of the internal pipe surface at the leakage position showing an oxide layer inside the crevice. The corrosion occurred exactly at the weld metal and the region at the margin of the damage shows the heat affected zone of the autogenous weld, with a refined grain size.
40
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 - Preferential Dissolution
Micrographic detail of the microstructure at the margin of the corroded area showing the heat affected zone of the autogenous weld, with a refined grain size.
37
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 - Preferential Dissolution