Atlas

2 cases · 41 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Product: Stud clear all

Results

SortNewestOldestTitle A-ZTitle Z-A
Aspect of the broken stud that was fastening a flanged line in a subsea body (tapped hole) using a nut. The fracture, transverse to the stud axis, occurred exactly at the body to flange interface. Adjacent to the fracture, all thread fillets (positioned inside the flange hole) presented cracks at the bottom of the thread. The stud was operating during seven years and was not corroded, indicating it was protected by the anodes. There are also deposits in the fillets suggesting the cathodic protection was effective even inside the flange hole.
799
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
Transgranular brittle aspect of the stud fracture surface. Evidences of hydrogen embrittlement.
965
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Fractography by SEMDf - Secondary Cracks

More from these cases

ML00136 — Hydrogen Cracks of Subsea StudsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Longitudinal section micrography in a position of the thread, far from the failure. The stud presented a quenching and tempering structure and the thread was machined.
84
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Machined Thread
Microstructure of the stud in the longitudinal section, presenting segregated bands, not uniformly distributed in the section. The bands are associated to elongated and aligned inclusions, and a refined microstructure, probably due to carbon and alloying elements concentration.
69
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Microstructure of the stud in the longitudinal section, out of a region of segregation, where the tempered martensitic microstructure appears more uniform.
72
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite
Micrographic detail of the segregated bands, not uniformly distributed in the section. The bands are associated to elongated and aligned inclusions, and a refined microstructure, probably due to carbon and alloying elements concentration. The localized microhardness (50g) in the band showed levels about 540HV, and out of the band, in the same localtion, presented an average hardness of 321 HV, indicating that the material is non uniform in the regions where there are bands.
66
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrographic detail of the martensitic structure of the stud in the longitudinal section, out of a region of segregation, where the microstructure appears more uniform and the microhardness is about 370HV (50g).
62
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Nital Etched Micrography by OMDf - Martensite

+24 more from this case →

ML00075 — Hydrogen Cracking of IN 718 Subsea FastenersM - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Macroscopic aspect of the stud that broke transverse to the axis, at the bottom of the thread fillet, presenting a brittle aspect.
64
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
The stud presents an austenitic structure, with primary and secondary precipitates of a size that is visible in low magnification microscopy.
55
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Austenite
The stud structure evidences grain boundaries precipitation of probably delta phase (an overaging of the hardening precipitate).
49
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Austenite
Micrography of a longitudinal section of the stud, at the fracture surface, in the thread.
44
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Fracture
Micrographic detail of a longitudinal section of the stud, at the fracture surface, in the thread. It is possible to see primary precipitates (yellow) already cracked and intergranular propagation.
37
VIEW
ML00075 / Jun.2018
Hydrogen Cracking of IN 718 Subsea Fasteners
M - NiCrFe AlloyP - StudAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched Micrography by OMDf - Intergranular Cracking

+5 more from this case →