Hydrogen

2 cases · 2 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Hydrogen — sub-branches

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
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 bolt fracture.  The fracture appearance is irregular and there are several secondary cracks from thread fillets.
245
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