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3 cases · 10 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Microstructure: Segregation Bands Standard: AISI Capture method: NItal Etched Macro clear all

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Macrography of the longitudinal section of the valve body, at the cracked position close to the actuator hole. The valve body is 40 mm thick and at this position it is possible to see that there are two regions where the body was welded, close to the inner surface (bottom) and at the close to the outer surface (top). The through wall crack presented a branch aspect close to the repair in the ID and a straight aspect when propagating from the repair.
55
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 MacroDf - Weld Repair
Macrography of a longitudinal section of the pipe at the fracture position, in the thicker thickness. The external side of the pipe (OD) is to the rigth side of the figure, and the internal side of the pipe is to the left of the figure. There are several secondary cracks, opened to the OD, created during bending.
37
VIEW
ML00159 / Mar.2020
Collapse of a Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - O&G Well DrillingCd - Ductile Behavior
Cm - NItal Etched MacroDf - Plastic Deformation
Macrography of a stud longitudinal sectiion at the fracture position (top of the figure). It is possible to see a large secondary crack at the bottom of the thread fillet adjacent to the fracture surface, 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.
56
VIEW
ML00136 / Jun.2018
Hydrogen Cracks of Subsea Studs
M - Low Alloy Medium Carbon QTP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - NItal Etched MacroDf - Secondary Cracks

More from these cases

ML00162 — Valve Body Crack Growth from Weld DefectsM - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Macrographic detail of the cracked position close to the actuator hole. The through wall crack presented a branch aspect in the weld metal, that is the original defect created during welding, and a straight aspect when propagating from the repair.
27
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 MacroDf - Hot cracking
Macrographic detail of the longitudinal section of the valve body, at the cracked position, a little far from the actuator hole. There is a straight crack, transverse to the thickness that clearly propagated by fatigue mechanism, from the region where the welding defects were created.
27
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 MacroDf - Fatigue Crack
Valve Body Crack Growth from Weld Defects
2
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 MacroDf - Crack
Valve Body Crack Growth from Weld Defects
1
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 MacroDf - Fatigue Crack
ML00159 — Collapse of a Drill PipeM - Low Alloy Medium Carbon QTP - Drill PipeAp - O&G Well DrillingCd - Ductile Behavior
Macrography of a longitudinal section of the pipe at the fracture position, in the thinner thickness. The external side of the pipe (OD) is to the left side of the figure, and the internal side of the pipe is to the rigth of the figure. The fracture occurred by shearing the pipe in a single event (probably due to tensile stresses during removal).
37
VIEW
ML00159 / Mar.2020
Collapse of a Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - O&G Well DrillingCd - Ductile Behavior
Cm - NItal Etched MacroDf - Ductile Fracture
Macrographic detail of the longitudinal section of the pipe at the fracture position, in the thicker thickness. The several secondary cracks, opened to the OD, were created during bending and shows evidences of compression, responsible for the increase in the pipe thickness.
33
VIEW
ML00159 / Mar.2020
Collapse of a Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - O&G Well DrillingCd - Ductile Behavior
Cm - NItal Etched MacroDf - Ductile Fracture
Macrographic detail of a longitudinal section of the pipe at the fracture position, in the thinner thickness. The external side of the pipe (OD) is to the left in the figure, and the internal side of the pipe is to the rigth in the figure. The fracture occurred by shearing the pipe in a single event (probably due to tensile stresses during removal).
24
VIEW
ML00159 / Mar.2020
Collapse of a Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - O&G Well DrillingCd - Ductile Behavior
Cm - NItal Etched MacroDf - Ductile Fracture