Donk: There are reference materials that describe bolt markings. You might try SAE and ASTM as a starting point. Bolts can be counterfeit and have correct markings. The hydrogen embrittlement issue is a separate one from counterfeit bolts. Non-counterfeit bolts can suffer HE also. Hope this helps! David Hendrix The Hendrix Group Inc.

DONK, There are some resources available on the internet where you can identify various ASTM and MIL-STD fittings Try these links: http://www.hudsonfasteners.com/fast_guide/fg_grade_markings.htm http://www.textronfasteningsystems.com/eng_tools_f/grades.html http://www.americanfastener.com/techref/grade.htm Let us know if this is what you require or if you are looking for additional information... There are engineering books available on fastener design and selection. As I see it, the only solution to the problem of counterfit and defective fasteners is the threat of a huge lawsuit byan agressive lawfirm. That type of "protection" seems to end at the US borderes..... Anybody else have ideas ???? What does the US airline industry do to protect themselves ? MJC