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Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Brittle Behavior clear all

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Aspect of the broken spring. The wire is 1 1/2" diameter and the ourter diameter of the spirals is 12 1/2", in a 20" height spring. It was broken in several pieces.
866
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - General View
Microscopic image by scanning electron microscope (SEM) of the ring surface that presented pites under fouling deposits.
522
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - Pitting
Draft of the completion riser after removal of the external case showing the hydraulic line position where the 316 tubing is welded by orbital autogenous GTAW to the Nitronic fitting (stab). In the design of these hydraulic lines, the position of the cracking in the fitting is associated to a slightly bent condition of the fitting due to the misaligment of the tubing axis and the stab axis in the connector, visible in the draft.
1081
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Identification drawingDf - General View
Aspect of the fitting welded to a tubing, ND 5/8" in a hydraulic line. The through wall cracking is longitudinal in the fitting side.
1032
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - General View
Micrographic detail of the through wall cracking, slightly branched and thin.
656
VIEW
ML00093 / Sep.2017
MIC of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
Cm - Nital Etched Micrography by OMDf - Cracking
The as polished micrographic aspect of the corroded surface shows pitting and several microcracks, probably associated to the biological attack and material embrittlement. Replication technique.
924
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - As polishedDf - Microcracks
Aspect of the broken disc spring, 1/4" thick, OD 10". The fracture is flat and transverse to the disc.
604
VIEW
ML00080 / Sep.2017
MIC of Stacking Disc Springs
M - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Brittle Fracture

More from these cases

ML00137 — Brittle Fracture of a 15-5 PH Valve SpringM - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Aspect of the fracture of the spring. Close to the surface the fracture presents the aspect of rusted spots.
132
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Fracture
The spring ruptured in several positions. This is the aspect of one of the fractures of the spring. In the initiation of the fracture (top side of the figure) the fracture presents a different morphology.
101
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Brittle Fracture
Microstructure of the spring in a transverse section, presenting an aged martensitic structure.
96
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Martensite
Corroded spots (shallow pits) at the spring surface.
84
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - At the Surface
Corroded spots (shallow pits full of products) at the spring surface.
80
VIEW
ML00137 / Mar.2021
Brittle Fracture of a 15-5 PH Valve Spring
M - Precipitation Hardened Stainless SteelP - SpringAp - Oil and GasCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - Corrosion

+22 more from this case →

ML00124 — MIC of a Martensitic Valve RingM - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
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
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
Micrography of a transverse section of the ring presenting a uniform tempered martensite structure.
43
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Kalling Etched Micrography by OMDf - Martensite
Microscopic details of the ring surface showing the fouling at the surface and localized corrosion under the deposits.
42
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - Pitting
Higher magnification of the localized corrosion, showing that there are cracks at the margin of the corroded region.
39
VIEW
ML00124 / Feb.2018
MIC of a Martensitic Valve Ring
M - Martensitic Stainless SteelP - ForgingAp - EnergyCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - Pitting

+11 more from this case →

ML00095 — MIC of a Riser Control LineM - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Aspect of the hydraulic line samples removed from service to be analyzed. Tubing and welded joint (bottom sample) between the 316 tubing (left side of the sample) and the nitronic fitting (right side of the sample). The cracking is located 10 mm far from the weld, autogenous orbital GTAW.
108
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - General View
Scanning electron microscopy image of the external surface of the line at the cracking position showing multiple cracks, branched, transverse to the line axis.
79
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - External Surface
Detail, by scanning electron microscopy, of the external surface of the line at the cracking position presenting branched cracks, transverse to the line axis. The surface of the fitting is fully stained (dark grey), from where the cracks start, indicating that the material loose passivation in these regions.
62
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - Branched Cracks
Detail of the welded joint between the 316 tubing (left side) and the nitronic fitting (right side). The through wall cracking is transverse to the line, in the fitting, 10 mm far from the weld, where the fitting was slightly bent to be assembled (cold bent).
65
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Welded Joint
The longitudinal section macrography of the welded joint sample shows that the cracks are positioned in the fitting, about 10 mm far from the weld.
60
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Longitudinal Section

+10 more from this case →

ML00094 — MIC of a Subsea Hydraulic LineM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Detail of the longitudinal through wall cracking in the fitting welded to a tubing, ND 5/8" in a hydraulic line.
87
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - External Surface
Macrography of a longitudinal section of the fitting to tubing weld, with the longitudinal cracking at the tubular fitting position.
69
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Kalling Etched MacroDf - Longitudinal Section
Aspect of the internal side of the fitting to tubing welded joint, after longitudinal cut. It is possible to see that the cracking (still filled with corrosion products) is located in the fitting side (left side) far from the welded joint to the tubing (right side).
58
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Internal Surface
Aspect of the internal side of the fitting, at the cracked position with corrosion products and several surface microcracks adjacent to the main crack.
52
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Surface AspectDf - Internal Surface
Aspect by scanning electron microscopy of the cracking at the external surface of the fitting.
47
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - External Surface

+13 more from this case →

ML00093 — MIC of a Drilling ToolM - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
The tool housing ID 1 1/2" presented a longitudinal through wall cracking, in two positions at 180°. The internal side of the housing presented several pits.
66
VIEW
ML00093 / Sep.2017
MIC of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Through Wall Cracking
Micrography of a longitudinal section of the housing presenting a uniform tempered martensitic structure. The material presented a thickness about 2.5 mm in the region where the cracking started.
52
VIEW
ML00093 / Sep.2017
MIC of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
Cm - Nital Etched Micrography by OMDf - Uniform Structure
Micrography of a longitudinal section of the housing presenting a uniform tempered martensitic structure.
51
VIEW
ML00093 / Sep.2017
MIC of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
Cm - Nital Etched Micrography by OMDf - Longitudinal Section
Aspect of the internal side of the housing presenting multiple cracks in longitudinal direction.
49
VIEW
ML00093 / Sep.2017
MIC of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Cracking
The microscopic aspect of the internal side of the housing evidences the characteristics of the multiple cracks, not directly related to pitting corrosion.
41
VIEW
ML00093 / Sep.2017
MIC of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Heat Treated PartAp - O&G Well DrillingCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - Cracks

+10 more from this case →

ML00092 — MIC of a Valve BodyM - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Aspect of the inner side of a valve body, showing regions of localized corrosion and rust, not expected for this stainless steel.
82
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Corrosion
Evidences of a stagnated fluid in the internal surface of the valve body.
61
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Internal Surface
Deep localized corrosion spots, rusted. There are indications that the roughness of the surface influences the localized corrosion location.
61
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Localized Corrosion
The macroscopic aspect of the surface after preparation. Grinding and polishing.
50
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Surface AspectDf - Localized Corrosion
The forged valve presented an uniform tempered martensitic structure, surface hardness 246HB. Replication technique.
42
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Kalling etched, OMDf - Martensite

+3 more from this case →

ML00080 — MIC of Stacking Disc SpringsM - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Macroscopic aspect of the fracture surface, showing a brittle behavior (chevron marks) and a starting point at the bottom of the groove in the right side of the figure.
42
VIEW
ML00080 / Sep.2017
MIC of Stacking Disc Springs
M - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Cm - Fracture Surface AspectDf - Brittle Fracture
Detail of the fracture starting point, in the bottom of the groove, where there is a pit about 0.5 mm depth.
36
VIEW
ML00080 / Sep.2017
MIC of Stacking Disc Springs
M - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Cm - Fracture Surface AspectDf - Brittle Fracture
Microscopic detail of the fracture surface in the position where the fracture is intergranular, probably due to the MIC attack creating an embrittled condition of the material.
31
VIEW
ML00080 / Sep.2017
MIC of Stacking Disc Springs
M - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Cm - Fractography by SEMDf - Intergranular Fracture
Microscopic detail of the fracture surface in the position where the fracture is intergranular, probably due to the MIC attack creating an embrittled condition of the material. A surface film is evident in this position suggesting that the fracture remained open and exposed to the environment during a certain time before the failure was detected.
29
VIEW
ML00080 / Sep.2017
MIC of Stacking Disc Springs
M - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Cm - Fractography by SEMDf - Intergranular Fracture
Fracture micromechanisms. Intergranular fracture in the top of the figure (close to the groove) and transgranular fracture in the bottom of the figure, where the mechanism changed to transgranular by quasecleavage.
27
VIEW
ML00080 / Sep.2017
MIC of Stacking Disc Springs
M - Low Alloy Medium Carbon QTP - SpringAp - SubseaCd - Brittle Behavior
Cm - Fractography by SEMDf - Intergranular Fracture

+6 more from this case →