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3 cases · 29 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Ferritic pearlitic Standard: API Capture method: Optical Microscope clear all

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Micrography of the pipe base metal, in a longitudinal section, presenting a slight banding and a refined structure.
147
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the pipe transverse section presenting a granular microstructure.
147
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 - Transverse Section
The micrography shows the region underbead, of the tube HAZ, responsible for the hydrogen cracking (fracture in the right side of the photo - black). The hardness of the HAZ is about 600 HV.
55
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Cracking

More from these cases

ML00153 — X52 in a Tubular StructureM - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Micrography of the pipe base metal, in a longitudinal section. The ferritic structure is refined and it is possible to identify a small variation in the ferritic grain size, that is promoting the slight banding effect.
119
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrographic detail of the very refined ferritic structure of the base metal, in the longitudinal section, indicating that the material was heat treated, since no banding is not detectable at this magnification.
101
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Grain refined structure
Micrography of the weded joint at the cap pass fusion line. The columnar structure of the weld metal is to the top of the figure; and it is possible to see the coarse grains at the heat affected zone. Both columnar structure and coarse grains are related to the previous austenite grain boundaries. From the fusion line to the base metal (in the bottom of the figure) the grain sizes are refined.
86
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Welded Joint
Micrography presenting the coarse grain heat affected zone of the welded joint, at the cap pass. The microstructure is bainitic.
82
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone
Micrographic detail of the bainitic structure of the coarse grain heat affected zone, close to the fusion line (to the top of the figure).
76
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Bainitic HAZ

+5 more from this case →

ML00140 — Preferential Corrosion of Pipe Seam WeldM - Low Carbon SteelP - Longitudinal Seam Welded PipeAp - ShipCd - Preferential Dissolution
Micrography of the pipe transverse section presenting a predominatly ferritic-perlitic microstructure.
132
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 - Ferrite and Pearlite
Micrographic detail of the predominatly ferritic-perlitic microstructure. Pipe transverse section.
95
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 - Ferrite and Pearlite
Micrography of the pipe in the leakage area, showing the preferential corrosion in the center of the autogenous weld and oxides inside the crevice, that appearas as a cracking but that is only a localized anodic process.
66
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 - Localized Corrosion
Micrographic detail of the autogenous seam weld. The localized dissolution occurrs exactly at the weld metal that presents a bainitic structure of average hardness about 230HV, compared to the heat affected zone presenting average of 202 HV and the base metal presenting average of 180HV.
57
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 - Localized Corrosion
Micrographic detail presenting the slighltly decarburized ferritic structure, with inclusions, in the center of the weld, surrounded by a bainitic structure and the preferential corrosion in the weld.
51
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 - Localized Corrosion

+5 more from this case →

ML00052 — Cold Cracks in API 5CT L80 Tube Welded to a Structural PartM - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Low carbon plate base metal presenting the ferritic perlitic structure.
55
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal
High Strenght Low Alloy steel tube, base metal, presenting the bainitic structure.
54
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the low carbon steel plate at the fusion line, presenting a bainitic structure at the HAZ and ferritic structure in the weld metal.
82
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Fusion Line
The micrography shows the martensitic region of the tube HAZ responsible for the hydrogen cracking, presenting too high hardness level (600 HV). It is a fresh martensite since the joint was welded in one pass and there was no PWHT.
45
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of the weld metal in the center of the fillet showing a 100% acicular ferrite that is a microestructure of a high strenght steel, evidenced the effect of the dilution of the tube chemistry in the weld metal.
40
VIEW
ML00052 / Apr.2017
Cold Cracks in API 5CT L80 Tube Welded to a Structural Part
M - Low Alloy SteelP - Seamless tubeAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Weld Metal

+1 more from this case →