rare bolt head mark 3

[Nitsugua]

Hi, here's a picture of a broken cap scew involved in an accident. We will call it the "F" bolt. Other bolts around are SS ASTM F593. Unfortunately, this only one does not have a stadard mark and nobody around know about it. Many manufacturer's charts have been viewed and no clue appears.

The question is: What is the bolt grade?

A simple magnetic test showed us a difference, the "F" bolt react to the magnet.

Look at the picture below.

Luc Perron, structural ingineer

Luc Perron, engineer
Unigec Experts-conseils

 

[RebelBrill]

This bolt has no grade. See the following link for some information on "suspect and counterfeit fasteners".

http://www.hss.energy.gov/csa/csp/sci/

 

[TheTick]

Bolt is broken + accident + possible counterfeit = ???

 

[btrueblood]

You can't say the bolt has no grade, just that it has no grade identifier. Depending on the spec. it was fabricated/purchased to, it may or may not need one. It's pretty clear that it is NOT compliant with ASTM F593, however.

The fact that it does not match adjacent fasteners is suspicious, but you can't claim counterfeiting without showing that somebody deliberately represented/sold the bolt in question as being the same as the adjacent fasteners. It could be that it was replaced in the field by somebody (maintenance tech) who didn't know better, or was installed originally by somebody who didn't know better, or because the bolt fell into the (wrong) bolt bin and it never got caught...

 

[KENAT]

Would a hardness test give some information to help you?

KENAT, probably the least qualified checker you'll ever meet...

 

[MintJulep]

There is no point in making a counterfeit "no grade" bolt.

Likewise, there is no point in making counterfeit bolts with an unknown manufacturer's mark.

 

[btrueblood]

I'd agree Mint, although maybe it's just a really poor job of counterfeiting

 

[InventorGod]

It may not be counterfeit at all though, it may be that it was made by the company that was using it or the company that made the machine it came off of. It may even be an expensive bolt or a rare one, and they took it to a machine shop, and they made one for them. Not really counterfeit, but not really legal either I guess.

 

[hydtools]

Here is a link to MIL-HNBK-75B that shows manufacturers marks. It is a 5meg+ pdf file.

http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=66904

Ted