Offshore

13 cases · 176 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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The repair weld presented several cracks in the weld metal, transverse to the weld, detected during inspection using magnetic particle test. The cracks were mainly located in regions of the structure where the repair was conducted by welding in the vertical position using 1/8" stick electrode.
710
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Aspect by NDTDf - Cracking
Transverse section of the blade showing large grains of this poliycristaline cast material.
421
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Coarse Structure
Regions of the pin thread presenting pitting corrosion.
635
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Surface Aspect by SEMDf - Localized Corrosion
Longitudinal section of the wire, close to the surface. Galvanized layer (zinc), 50 microns thickness.
368
VIEW
ML00036 / Jan.2018
High Strength Medium Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Cm - Nital Etched Micrography by OMDf - Surface Layer
Mooring chain aspect, after several years of operation. Transverse cracking, revealed by dye check, close to the flash butt weld.
441
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Aspect by NDTDf - Crack

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ML00010 — Cold Cracks in a Gouged Weld MetalM - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
After grinding to remove the cracks, it was possible to see that they originated in the root, with longitudinal and transverse cracking, and localized in the weld metal only.
167
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Aspect by NDTDf - Cracking
Acetate metallographic replica from the surface, before cracking removal, showing the intergranular morphology of the cracks in a very refined weld metal structure.
123
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital etched, OMDf - Intergranular Cracking
Detail of the acetate metallographic replica from the surface, before cracking removal, showing the (previous austenite) intergranular morphology of the cracks in a very refined weld metal structure.
107
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital etched, OMDf - Intergranular Cracking
Tempered martensitic structure of the plate base metal.
93
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal
Detail of the tempered martensitic structure of the plate base metal. Hardness level of 27 HRc.
92
VIEW
ML00010 / Oct.2017
Cold Cracks in a Gouged Weld Metal
M - Low Alloy Low Carbon QTP - Rolled PlateAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Base Metal

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ML00042 — Gas Turbine Blade IN 939, CoatedM - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Micrography of the blade, view inside the grain. The intragranular precipitation presents one unique size of precipitation, not yet coalesced, although the blade was in high temperature service for 50.000 hours. Etched by H2SO4 + HNO3 + H3PO4 reagent.
66
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - Micrography by SEMDf - Intragranular Secondary Precipitation
Micrography close to the surface of the blade, showing the diffusion coating (aluminum base alloy) that is still sound. No strong oxidation or erosion was detected.
53
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Coating
Micrographic detail of the diffusion coating. H2SO4 + HNO3 + H3PO4 etched.
47
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - Micrography by SEMDf - Coating
Micrography as polished of the region where there was a refrigeration hole, presenting a cracking.
35
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - Micrography by OMDf - Cracking
The cracking from the refrigeration hole presents an intergranular morphology, as shown in the micrography of a transverse section of the blade.
35
VIEW
ML00042 / Apr.2017
Gas Turbine Blade IN 939, Coated
M - NiCrCo AlloyP - CastAp - Gas TurbineCd - Intergranular Cracking
Cm - H2SO4+HNO3+H3PO4 Etched MicroDf - Intergranular Cracking
ML00016 — SCC in Free Cutting 303SSM - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Regions of the localized corrosion spots associated to non metallic inclusions.
123
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Surface Aspect by SEMDf - Non Metallic Inclusions
The macrography of the longitudinal section of the pin (9.5 mm nominal diameter) shows the localized corrosion associated to the non metallic inclusions.
107
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Localized Corrosion
The low magnification micrography of the longitudinal section of the pin shows the localized corrosion associated to the non metallic inclusions.
89
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Micrography by OM using A262 Method ADf - Localized Corrosion
The pin microstructure in the longitudinal section shows austenitic structure, free from carbides, and sulfide inclusions that characterize the free cutting condition of this stainless steel.
77
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Micrography by OM using A262 Method ADf - Non Metallic Inclusions
The micrographic detail of the longitudinal section of the pin shows the localized corrosion associated to the non metallic inclusions.
67
VIEW
ML00016 / Apr.2017
SCC in Free Cutting 303SS
M - Austenitic Stainless SteelP - Machined PartAp - OffshoreCd - Stress Corrosion
Cm - Micrography by OM using A262 Method ADf - Localized Corrosion

+3 more from this case →

ML00036 — High Strength Medium Carbon Steel WireM - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Longitudinal section of the 3.6 mm wire, presenting a refined structure.
46
VIEW
ML00036 / Jan.2018
High Strength Medium Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Longitudinal section of the 3.6 mm wire, presenting a strain hardened structure, predominantly perlitic.
41
VIEW
ML00036 / Jan.2018
High Strength Medium Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Longitudinal section of the 3.6 mm wire, presenting a strain hardened structure, predominantly perlitic.
38
VIEW
ML00036 / Jan.2018
High Strength Medium Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Cm - Nital Etched Micrography by OMDf - Predominantly Pearlitic
Transverse section of the 3.6 mm wire, presenting a refined structure.
32
VIEW
ML00036 / Jan.2018
High Strength Medium Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Cm - Nital Etched Micrography by OMDf - Transverse Section
Transverse section of the 3.6 mm wire, presenting a refined structure predominatly perlitic.
19
VIEW
ML00036 / Jan.2018
High Strength Medium Carbon Steel Wire
M - Medium Carbon SteelP - WireAp - OffshoreCd - Typical manufacturing
Cm - Nital Etched Micrography by OMDf - Transverse Section

+1 more from this case →

ML00013 — Welding Cracks in Mooring ChainM - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Micrography of a longitudinal section of the mooring chain in the base metal. The low magnification reveals the banded structure of the rolled bar. The base metal microstructure is bainitic..
79
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrographic detail of the bainitic microstructure of the base metal in the longitudinal section.
72
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Bainite
Micrography of a longitudinal section of the mooring chain at the flash welded region. The banded structure is deformed by the upset, close to the weld metal that is ferritic-bainitic.
61
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Bainitic Ferrite
Micrographic detail of the ferritic-bainitic weld metal, autogenous flash butt weld.
56
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Nital Etched Micrography by OMDf - Bainitic Ferrite
Welded region etched to reveal impurities. The banded structure creates a continuous network parallel to the weld metal.
50
VIEW
ML00013 / Apr.2017
Welding Cracks in Mooring Chain
M - Low Alloy Low Carbon QTP - Welded PartAp - OffshoreCd - Welding Defect
Cm - Micro by OM, picric acid+FeCl3+H2O etchDf - Segregated Regions

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