Aspect Before Analysis

10 cases · 20 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Damage Microstructure: Tempered Martensite Standard: UNS clear all

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Aspect of the barrel nut that is broken in a brittle way (without plastic deformation). The Nut diameter is 1", the nut length is 2" and the bolt thread is 1/2" (nominal diameter).
753
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Aspect Before AnalysisDf - General View
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
Allen stud, 1/2" nominal diameter, cadmium plated and chromate treated, cracked during assembling external parts in a gate valve.
63
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
Aspect of the broken bolt, 5/8" Allen, socket head cap screw, originally 1 3/4" long, broken in subsea service under cathodic protection. The bolt presents a zinc coating.
116
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
Macroscopic aspect of the crack in the valve ring surface. A leakage was detected during testing after 6 months out of service and the inspection identified several transverse cracks in the forged ring. The valve was installed for one year, but it was not drained during the time it was out of service. The cracks were located in regions that were rusted and presenting a biological fouling.
50
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - At the Surface
Aspect of the broken padeye. The outer diameter is about 10" and the thickness of the casting is about 2".
22
VIEW
ML00098 / Nov.2017
Brittle Fracture of a Casting Lifting Device
M - Low Alloy Medium Carbon QTP - CastingAp - LiftingCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - General View
Fracture appearance of the 1 1/4" diameter link. The fracture is flat and presented no evidences of plastic deformation, suggesting a brittle behavior.
54
VIEW
ML00079 / Jul.2017
Hydrogen Cracking of a Maritime Chain Link
M - High Strength Low AlloyP - Chain LinkAp - OffshoreCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
Aspect of the bolt fracture. The fracture appearance is irregular and there are several secondary cracks from thread fillets.
245
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View

More from these cases

ML00148 — Brittle Fracture of a 420 SS Barrel NutM - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Visual aspect of both sides of the fractures. They present a macroscopically brittle aspect, with chevron marks indicating the starting point at the thinner edge of the thread.
81
VIEW
ML00148 / Sep.2018
Brittle Fracture of a 420 SS Barrel Nut
M - Martensitic Stainless SteelP - Barrel NutAp - LiftingCd - Heat Treatment Defect
Cm - Aspect Before AnalysisDf - Fracture
ML00136 — Hydrogen Cracks of Subsea StudsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Macroscopic view of the fracture surface showing that there is a flat appearance of the fracture close to the bottom of the thread (upper side of the figure) and a flat, but rough appearance in the center of the stud. No evidences of corrosion in the thread fillets indicating that the stud was protected.
59
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Brittle Fracture
Macroscopic detail of the stud, adjacent to the fracture, showing that there are several secondary cracks at the bottom of the thread fillets, without any deformation evidence. This reveals a brittle material behavior, although the hardness measured at the stud end revealed 33HRc, as should be expected by the material specification.
59
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Secondary Cracks
ML00127 — Hydrogen Cracks of Cadmium Plated StudsM - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Allen stud, 1/2" nominal diameter, cadmium plated and chromate treated, cracked during assembling external parts in a gate valve.
40
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Fracture
Allen stud, cadmium plated and chromate treated. The fracture appearance is brittle.
38
VIEW
ML00127 / May.2018
Hydrogen Cracks of Cadmium Plated Studs
M - Low Alloy Medium Carbon QTP - Allen StudAp - Oil and GasCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Fracture
ML00126 — Hydrogen Fracture of Subsea Allen BoltsM - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Aspect of the fracture of a small Allen bolt, nominal diameter 5/8" 1 3/4" long, class 12.9, that was operating in subsea environment during 5 years. The fracture is rusted but the thread still presents the zinc coating.
81
VIEW
ML00126 / Mar.2018
Hydrogen Fracture of Subsea Allen Bolts
M - Low Alloy Medium Carbon QTP - Coated ProductAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
ML00124 — MIC of a Martensitic Valve RingM - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Macroscopic aspect of the crack after cleaning the ring surface. Transverse cracks were identified associated to pitting corrosion.
44
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Localized Corrosion
ML00098 — Brittle Fracture of a Casting Lifting DeviceM - Low Alloy Medium Carbon QTP - CastingAp - LiftingCd - Brittle Fracture
Aspect of the fracture surface, showing a brittle morphology. Flat fracture with chevron marks from regions close to the internal diameter of the padeye, where there are secondary cracks.
22
VIEW
ML00098 / Nov.2017
Brittle Fracture of a Casting Lifting Device
M - Low Alloy Medium Carbon QTP - CastingAp - LiftingCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Fracture
ML00077 — Hydrogen Cracking of LAS Subsea BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Aspect of the bolt surface with a detail of a secondary crack at the first thread fillet, close to the bolt head.
147
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Secondary Cracks
Aspect of the bolt fracture. The fracture appearance is irregular.
137
VIEW
ML00077 / Jun.2018
Hydrogen Cracking of LAS Subsea Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Fracture