Subsea

11 cases · 20 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Condition: Hydrogen Capture method: Aspect Before Analysis clear all

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General aspect of the 5/8" allen bolt that was found fractured in an instrument connected to a subsea BOP. The fracture presented a brittle aspect and occurred at the bolt head to threaded body transition.
1495
VIEW
ML00139 / Jun.2018
Hydrogen Fracture of a 17-4 PH Allen Bolt
M - Precipitation Hardened Stainless SteelP - Allen BoltAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Fracture
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
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
Aspect of the fracture that occurred in the connection between the pin of one DP and the box of other DP, in the pin side. The photo presents the pin still connected in the box. The flat fracture indicates a brittle behavior.
641
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View
Aspect of the fracture surface of the pin, still assembled in the box (that is externally to the pin). The pin fracture is flat, presenting radial marks.
791
VIEW
ML00088 / Dec.2017
Hydrogen Cracking of an API 5D S135 Drill Pipe
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Brittle Fracture
Brittle aspect of the failure of the conector in the male thread. Both sides of the fracture.
96
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - 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
The stainless steel spring broke without any evidence of plastic deformation. The round wire 1/8" diameter has ruptured in a brittle way in this 2" long spring of external diameter of 1/2".
73
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - General View

More from these cases

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
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
ML00009 — Hydrogen Cracking of a 5" Drill Pipe S135M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Aspect of the broken pin after removal from the box end.
125
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Brittle Fracture
Detail of the fracture surface with a starting point at the external surface of the pin.
91
VIEW
ML00009 / Sep.2017
Hydrogen Cracking of a 5" Drill Pipe S135
M - Low Alloy Medium Carbon QTP - Drill PipeAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Brittle 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
ML00076 — Hydrogen Cracking of a 17-7 PH Subsea SpringM - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Detailed aspect of the spring close to the fracture position. The wire surface shows a morphology that reveals the material structure.
58
VIEW
ML00076 / Jun.2017
Hydrogen Cracking of a 17-7 PH Subsea Spring
M - Precipitation Hardened Stainless SteelP - WireAp - SubseaCd - Hydrogen Embrittlement
Cm - Aspect Before AnalysisDf - Fracture