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ML00014 - Apr.2017

Pitting Corrosion in 316SS Pipe

Micrography of a transverse section of the pipe, presenting the pitting corrosion. As polished.

6

310
of a of the , presenting the . .
M

Material

Austenitic Stainless Steel
  • UNS S31603
  • ASTM A 312 TP 316L
Ds

Description

The 2” of chemicals was operating at ambient temperature (tropical), in a shadow location of a . After two years in service the lines were leaking. The metallurgical analysis showed that the occurred from the external side of the , that presented a “rusted” aspect. propagated through wall. The lack of rain washing created evaporation/condensation cycles that could concentrate chlorides, as well as increase biological proliferation.

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Chemistry (% in weight)

Pipe Product Analysis

0.02C; 0.41Si; 1.76Mn; 0.034P; 0.024S; 16.8Cr; 11.1Ni; 2.0Mo.

Associated Images
Transverse section of the 2" diameter pipe at the pitting location. The pipe was leaking.
1322
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Transverse Section AspectDf - Pitting
The external surface of the 2" diameter pipe is rusted and the leakage is associated to “holes” that appear very small at the surface but that open a large hole in the middle of the thickness.
507
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Aspect Before AnalysisDf - Corrosion
Image of the external surface of the pipe presenting regions of localized corrosion (in the beginning) and deposits
387
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Surface Aspect by SEMDf - Corrosion
Image of the external surface of the pipe presenting deposits where there is a localized corrosion at the surface.
326
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Surface Aspect by SEMDf - Corrosion
Image of the external surface of the pipe presenting the aspect of the localized corrosion by pitting.
297
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Surface Aspect by SEMDf - Pitting
Micrography of a transverse section of the pipe, presenting the pitting corrosion. As polished.
310
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Micrography by OMDf - Pitting
Austenitic structure at the transverse section of the pipe, free from carbides.
277
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Micrography by OM using A262 Method ADf - Austenite
Austenitic structure, free from carbides, exactly in the region of the pitting, indicating that the corrosion is not associated to the material microstructure.
261
VIEW
ML00014 / Apr.2017
Pitting Corrosion in 316SS Pipe
M - Austenitic Stainless SteelP - Seamless PipeAp - FPSOCd - Pitting Corrosion
Cm - Micrography by OM using A262 Method ADf - Austenite