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ML00092 - Sep.2017

MIC of a Valve Body

Deep localized corrosion spots, rusted. There are indications that the roughness of the surface influences the localized corrosion location.

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Deep spots, rusted. There are indications that the roughness of the surface influences the location.
M

Material

Martensitic Stainless Steel
  • AISI 410
Ds

Description

The inner side of a body in a Xtmas Tree equipment was temporarily exposed to completion and production fluids and remained with a small amount of stagnated fluid, leading to . The aggressive attack of the in a very short time suggests a biological effect (), with and by . This analysis was non destructive (PMI chemistry and metallographic ).

C

Chemistry (% in weight)

PMI equipment

0.47Si; 0.59Mn; 11.6Cr; 0.04Ni; 0.00Mo; 0.13Cu; 0.15W.

Associated Images
The as polished micrographic aspect of the corroded surface shows pitting and several microcracks, probably associated to the biological attack and material embrittlement. Replication technique.
924
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - As polishedDf - Microcracks
Aspect of the inner side of a valve body, showing regions of localized corrosion and rust, not expected for this stainless steel.
82
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Corrosion
Evidences of a stagnated fluid in the internal surface of the valve body.
61
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Internal Surface
Deep localized corrosion spots, rusted. There are indications that the roughness of the surface influences the localized corrosion location.
61
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Localized Corrosion
The macroscopic aspect of the surface after preparation. Grinding and polishing.
50
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Surface AspectDf - Localized Corrosion
The forged valve presented an uniform tempered martensitic structure, surface hardness 246HB. Replication technique.
42
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Kalling etched, OMDf - Martensite
Micrographic detail of the martensitic structure, hardness level about 246HB. Replication technique.
40
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Kalling etched, OMDf - Martensite
The micrographic aspect of the corroded surface, after polishing and etching with Kalling, shows the margin of one pit and microcracks propagating through previous austenite grain boundaries of the martensitic structure, probably associated to the biological attack and material embrittlement. Replication technique.
42
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Kalling etched, OMDf - Pitting
Micrographic details of microcracks propagating through previous austenite grain boundaries of the martensitic structure. Replication technique.
41
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Kalling etched, OMDf - Microcracks