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Appendix E: Selected Subsea Bolt Failures
Pages 156-159

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From page 156...
... in 1998-2000. As a consequence, bolt hardness was reduced to HRC34; an ICS safety alert was issued related to removal of metallic coating from bolt holes.
From page 157...
... The high material hardness, yield strength, bolt design, impressed current and thermal spray aluminum coating were identified as contributing factors for the failure." (Product Advisory issued by Vetco Gray on April 8, 2005) 2012-2013 Flanged riser bolt/bolt Per QC-FIT Report, Appendix G, "Riser BSEE, 2014 insert failure bolt inserts (nuts)
From page 158...
... long; Stress Engineering Services indicated "failures of the incident bolts initiated due to hydrogen stress cracking" and "it is likely that atomic hydrogen present in the bolts due to the plating process (and not removed via a subsequent bake-out) played a major role in the failures" (GE issued GE Safety Notice SN 13-001, REV.
From page 159...
... Of these brittle fractures 57% were attributed to hydrogen embrittlement, 29% to temper embrittlement, and 14% to other/undetermined causes. SOURCES: Adamek, F.C., Adamek Engineering and Technology Solutions LLC, "A Historical View of Subsea Bolting," presentation to the Workshop on Bolting Reliability for Offshore Oil and Natural Gas Operations, April 10-11, 2017.

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