Sampling and Analysis

6 cases · 38 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Segregation Bands Capture method: Optical Microscope clear all

Sampling and Analysis — sub-branches

Base Metal 7Fusion Line 1Heat Affected Zone 6Longitudinal Section 6Microhardness Indentations 1Transverse Section 2Weld Metal 12Weld Repair 3

Results

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Low magnification micrography presenting segregation bands in a martensitic structure. In the segregated regions the Nital etch effect is lower and the bands appear lighter. The black spots and lines are inclusions (some elongated) in the band.
91
VIEW
ML00182 / Jul.2022
Brittle Fracture of a LAS Fixing Rod
M - Low Alloy Medium Carbon QTP - StemAp - Mechanical IndustryCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
BASE METAL SURFACE - Ferritic structure, grain refined.
90
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of a transverse section of the spring, at the surface showing pits full of deposits.
36
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Transverse Section
Low magnification micrography at the weld repair close to the internal surface of the valve body, in a longitudinal section. Weld metal to the bottom and heat affected zone to the top.
42
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Repair
Micrography of a longitudinal section of the bolt, as polished, presenting brittle Intergranular and transgranular cracks, transverse to the bolt axis.
94
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Micrography by OMDf - Longitudinal Section
The liquation crack is a hot crack in the base metal (at the HAZ) that induces a solidification crack in the weld metal.
66
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Weld Metal

More from these cases

ML00182 — Brittle Fracture of a LAS Fixing RodM - Low Alloy Medium Carbon QTP - StemAp - Mechanical IndustryCd - Brittle Fracture
Low magnification micrography, revealing (in black) the impurities in the segregated bands.
63
VIEW
ML00182 / Jul.2022
Brittle Fracture of a LAS Fixing Rod
M - Low Alloy Medium Carbon QTP - StemAp - Mechanical IndustryCd - Brittle Fracture
Cm - Micro by OM, picric acid+FeCl3+H2O etchDf - Longitudinal Section
ML00177 — Cr-Mo Seam Welded TubeM - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
HAZ SURFACE
72
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Last Bead HAZ
HAZ SURFACE
66
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Last Bead HAZ
WELD METAL SURFACE
47
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Weld Metal in the Cap
WELD METAL SURFACE
43
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Weld Metal in the Cap
BASE METAL T/2
41
VIEW
ML00177 / Dec.2021
Cr-Mo Seam Welded Tube
M - CrMo SteelP - Longitudinally Seam WeldedAp - Fired HeaterCd - Not according to spec
Cm - Nital Etched Micrography by OMDf - Base Metal

+9 more from this case →

ML00172 — Brittle Fracture of a LAS Valve SpringM - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Micrography of the transverse section of the spring wire, in the center, presenting a refined structure and segregation bands that are detected only in low magnification.
24
VIEW
ML00172 / Mar.2021
Brittle Fracture of a LAS Valve Spring
M - Low Alloy Medium Carbon QTP - SpringAp - Oil and GasCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Transverse Section
ML00162 — Valve Body Crack Growth from Weld DefectsM - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Low magnification micrography at the weld repair close to the internal surface of the valve body, in a longitudinal section. Weld metal to the right and heat affected zone to the left.
30
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Repair
Micrography of the weld repair at the fusion line. At this magnification it is possible to identify several voids at interdendritic positions.
26
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Repair
Micrographic detail of the weld metal presenting hot cracks, at interdendritic positions, interconected.
28
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Metal
Microstructure of the weld metal close to the fusion line, showing that the dilution effects created zones of higher carbon content, creating a martensitic plus retained austenite microstructure.
29
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Metal
Micrography in low magnification of the cracks in the repair weld metal, showing the dendritic aspect of the hot cracks, formed during welding due to the high content of impurities in a high strength weld metal.
26
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Nital Etched Micrography by OMDf - Weld Metal
ML00077 — Hydrogen Cracking of LAS Subsea BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Micrography of a longitudinal section of the bolt, showing the (secondary) crack propagating, transverse to the bolt, from a thread fillet.
91
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of the (secondary) crack propagating transverse to the bolt, from a thread fillet.
91
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of the (secondary) crack propagating transverse to the bolt, from a thread fillet.
80
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Micrographic detail of the banded region, with microhardness identations indicating that the longitudinal bands are harder than the rest of the structure. The measurements in the band are 466, 447 and 460 HV50g; and out of the band are 358, 360 and 362 HV50g, from the top to the bottom.
86
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Microhardness Indentations
ML00072 — Liquation Cracks in a High Strength JointM - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Micrographic detail of the cracks at the fusion line of the welded joint, at the connector side. The cracking presents morphology of melting regions of impurities at grain boundaries of the large grains of the heat affected zone (HAZ).
57
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Fusion Line
Micrography of the AISI 4130 forging, 5/8" thickness, close to the welded region, in the longitudinal section.
42
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal Left Side
Micrographic detail of the AISI 4130 forging, 5/8" thickness, close to the welded region, in the longitudinal section.
45
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal Left Side
Micrography of the X65 pipe, 5/8" thickness, in the longitudinal section.
45
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal Right Side
Micrographic detail of the X65 pipe, 5/8" thickness, in the longitudinal section.In the center of the pipe thickness there is a segregation band of bainitic structure. The cracking was not associated to the pipe but to the other side, the forged connector.
43
VIEW
ML00072 / Jan.2018
Liquation Cracks in a High Strength Joint
M - Low Alloy Medium Carbon QTP - Longitudinal Seam Welded PipeAp - O&G Well DrillingCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal Right Side

+2 more from this case →