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3 cases · 41 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Mechanical Fatigue clear all

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Aspect of a flared tubing, cold deformed at 37°, and the circumferential cracking.
483
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
Aspect of the bolt fracture surface by scanning electron microscopy, (SEM) presenting striations that indicate a FATIGUE micromechanism. The bolt is of a medium strength (class 8.8) low alloy steel, medium carbon, quenched and tempered.
1123
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Fractography by SEMDf - Fatigue Fracture
Micrographic detail of the fatigue cracking at the margin of the flange to shell fillet weld.
484
VIEW
ML00050 / Nov.2017
Fatigue Failure of a 316SS Pressure Stabilizer
M - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Cm - Micrography by OM using A262 Method ADf - Fatigue Crack

More from these cases

ML00167 — Fatigue of a Flared Tubing ConnectionM - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Same flared tubing, with a circumferential crack, with the focus at the internal side.
65
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
Micrography of a longitudinal section of the tubing showing a granular structure, austenitic.
52
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Oxalic Acid Electrolytic EtchDf - Longitudinal Section
Micrography of a longitudinal section of the tubing, showing the austenitic structure free from strain hardening and free from grain boundary carbides.
51
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Oxalic Acid Electrolytic EtchDf - Austenite
Micrographic detail of the austenitic structure, free from strain hardening and free from grain boundary carbides.
54
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Oxalic Acid Electrolytic EtchDf - Austenite
Low magnification fractography by scanning electron microscopy, after a complete opening of the crack. At this magnification no micromechanism is evident.
51
VIEW
ML00167 / Aug.2020
Fatigue of a Flared Tubing Connection
M - Austenitic Stainless SteelP - TubingAp - EngineCd - Mechanical Fatigue
Cm - Fractography by SEMDf - Fracture

+8 more from this case →

ML00130 — Fatigue Fracture of Overloaded BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
The four bolts have fractured in the same position, close to the end, and the corrosion marks in the thread suggest that they have been tightened only a few fillets in a tapped hole. This condition could be responsible for overloading the fillets, relaxing the applied bolt preload, and intensifying cyclic stresses.
192
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
The corrosion marks in the thread surface indicate that the bolt was not properly tightened in the tapped hole. The length of thread engagement should be at least 1x of the bolt diameter, in this case 3/8".
170
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
Macroscopic aspect of the bolt fracture. Part of it is flat from the bottom of the thread.
166
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - Fracture
The head of the bolts presented the marks that indicated they were manufactured to meet ASTM A449 type 1 bolt, that is a medium strength low alloy steel, quenched and tempered.
148
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - At the Surface
Aspect of the fracture surface in low magnification, showing a flat aspect (associated to a fatigue fracture micromechanims) and a rough aspect (associated to a ductile fracture micromechanism).
167
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Fractography by SEMDf - General View

+12 more from this case →

ML00050 — Fatigue Failure of a 316SS Pressure StabilizerM - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Aspect of the equipment presenting a through wall cracking at the margin of the fillet weld.
142
VIEW
ML00050 / Nov.2017
Fatigue Failure of a 316SS Pressure Stabilizer
M - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - Cracking
Macrography of the welded joint between the flange and the shell, indicating the position where the cracking was detected, at 90°.
116
VIEW
ML00050 / Nov.2017
Fatigue Failure of a 316SS Pressure Stabilizer
M - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Welded Joint
The shell plate micrography showed an austenitic structure.
101
VIEW
ML00050 / Nov.2017
Fatigue Failure of a 316SS Pressure Stabilizer
M - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Cm - Micrography by OM using A262 Method ADf - Austenite
The macrography of a transverse section of the shell to flange weld (Lepto's etch) shows that the cracking occurred through the shell plate thickness, at the margin of the fillet weld.
93
VIEW
ML00050 / Nov.2017
Fatigue Failure of a 316SS Pressure Stabilizer
M - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Cm - Transverse Section AspectDf - Cracking
Fracture surface after opening the shell cracking, presenting fatigue striation. The fracture presents also foreign particles.
132
VIEW
ML00050 / Nov.2017
Fatigue Failure of a 316SS Pressure Stabilizer
M - Austenitic Stainless SteelP - Fabrication WeldAp - Chemical IndustryCd - Mechanical Fatigue
Cm - Fractography by SEMDf - Fatigue Striation

+3 more from this case →