SPRING 2018

26 THE DISTRIBUTOR’S

26 THE DISTRIBUTOR’S LINK Carmen Vertullo Lead Trainer, Fastener Training Institute® FASTENER TRAINING INSTITUTE ® 5318 East 2nd Street #325, Long Beach, CA 90803 TEL 562-473-5373 FAX 661-449-3232 EMAIL info@fastenertraining.org WEB www.fastenertraining.org HYDROGEN EMBRITTLEMENT IN FASTENERS CASE STUDIES - PART 2 This is the second in our series of articles on case studies of hydrogen embrittlement in fasteners. If you are not familiar with hydrogen embrittlement I recommend that you read the previous issue’s case study and three other articles I have written on the subject for the Distributor’s Link Magazine. In our previous case study we had a situation in which there was no real hydrogen embrittlement in the product, but because of lack of process control and specification knowledge the supplier and the end user suffered some pain. It was not significant and the outcome was positive for all involved. This current case also involves lack of specification understanding, however it involves real hydrogen embrittlement where the consequences were severe. It serves as an excellent illustration of why end users and suppliers should have a thorough understanding of the fastener and coating specifications they are working with. In the end, we will use this study to help you understand two important plating specifications and how to make informed decisions regarding their use. CASE NUMBER 2: Subsea Oil Rig Bolting and Zinc Plating Specifications Over the past 5 years or so there have been a series of bolting failures in subsea oil drilling equipment. The investigations, repair of the failures, bolting replacement worldwide and the associated drilling rig downtime cost many millions of dollars, not to mention the environmental impact, which fortunately has been minimal. BSEE, the Bureau of Safety and Environmental Enforcement TECHNICAL ARTICLE and API, the American Petroleum Institute, along with other organizations have been at the front of these investigations. Hydrogen embrittlement was identified as the cause of failure in some of these cases. While experts agree that hydrogen embrittlement was indeed involved, the type of hydrogen embrittlement and the root cause of these failures is still a subject of controversy. When the root cause of any failure is elusive or not properly identified, applying an effective preventive action is not possible. In at least one case of this subsea bolting, the hydrogen embrittlement was attributed to the fact that the bolts were zinc plated and not properly baked according to the plating specification used, ASTM B633. When hydrogen embrittlement occurs under these conditions it is called internal hydrogen embrittlement. Baking the parts for some amount of time, a few hours to 24 hours or more, is the prescribed method to drive out the hydrogen and prevent hydrogen embrittlement from occurring. Many experts, reports, presentations and articles have indicated that improper baking was the cause of the hydrogen embrittlement in these cases. Other experts, more familiar with ASTM specifications for both fasteners, plating, and hydrogen embrittlement, could easily tell that improper baking was not the cause of this hydrogen embrittlement failure. Those experts are Joe Greenslade, the past Director of Engineering Technology of the Industrial Fasteners Institute (IFI), and Salim Brahimi, a renowned hydrogen embrittlement researcher and the current IFI Director of Engineering Technology. CONTINUED ON PAGE 110