Grade 8 Bolt Marking Symbol

[tfro]

I have a bolt that is now damaged and needs replacement. The bolt has the normal 6 lines indicating it is a SAE Grade 8 bolt, but also has a small triangle between two of the lines. I don't recognize this marking and can't find any references stating its meaning. What does this triangle mean?

It's a 5/8-11 x 3" partially threaded, if that matters.

 

[TVP]

That symbol is likely the manufacturers identification insignia. Use the following link to see which company uses it:

http://www.uspto.gov/web/offices/tac/fqa/active.pdf

 

[CoryPad]

The triangle is the manufacturers identification. The company is Infasco:

http://www.infasco.com/infasco/English/index.html

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[tfro]

Yep, that's it. Thanks.

Do you mind telling me how you found that, or were you familar with the brand?

 

[reidh]

Some head marking information can be found at:

http://www.unified-eng.com/scitech/bolt/boltmarks.html

If you really need to know the manufacturer by the head bolt marking, you can purchase a book from the Industrial Fasteners Organization that has many manufacturers (over 1000 I think) and their head markings at:

http://www.industrial-fasteners.org/publications.php?cat=2

Reidh

 

[mayt4u]

tfro,
Hi, does it matter? A grade 8 is a grade 8. The symbol is for ISO tracking. All American and/or World follow the specs. for manufacturing of bolt, nuts and washers. (hopefully).
Cheers
Robert
Could be worse, could be me!

 

[IRstuff]

Just bear in mind that there were a rash of counterfeit grade 8's some years ago.

TTFN

Eng-Tips Policies FAQ731-376

 

[tfro]

mayt4u,

No, it doesn't matter at all since it's only a manufacturing identifier (but I didn't know that, so that's why I started the thread). I work on products that don't require graded bolts, so I've never run across this before.

I was assuming that any grade 8 bolt would be fine, but since I wasn't sure I figured I'd ask and see if I could learn something (which I did).

-Thomas

 

[CoryPad]

I was familiar with the brand.

 

[zuccus]

Good post tfro, I learned something new also. Also wondered what those markings meant.

Zuccus

 

[reidh]

"does it matter? A grade 8 is a grade 8."

It DOES matter. If you think for a minute that the quality controls are the same between all manufacturer's, you are crazy. We have had problems before in which we were using a grade 8.8 or 12.9 bolt and it was failing. Independent lab tests proved that the bolt was not manufactured to the standard, which was the reason for failure. These were not counterfeit bolts either, they were traced directly to the manufacturer.

In case anybody was wondering, the head marking was "WT".

Reidh

 

[tfro]

Any suggestions on finding reliable vendors? Like I mentioned earlier, I don't deal with these types of bolts at work but I do use them for personal use (this particular bolt is an aftermarket suspension part). I'd like to find a good vendor to use, and price isn't really too much of an issue since I'm ordering in qtys under 10 and failure leads to serious issues.

-Thomas

 

[reidh]

Depending on your location in the world, your best bet may be to order the bolt to a mil-spec if you are in the US. There are tighter quality controls for mil spec bolts compared to the SAE J429 standard.

I imagine my above comment may open a can of worms on this forum.

Reidh