OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Dodgy bolts. What Grade are they?

So I needed some high tensile bolts that are around Grade 5-8. I scratched around in the shed and came across these ones from years past. I can't recall purchasing them but I guess they came from a local hardware or chain store.

At first I thought they must be Grade 7, but now I wonder if this is just a brand letter "L". It looks more like an "L" than a "7". As for the other three markings on the head, I have no idea. Perhaps this is meant to represent three lines, but it actually looks more like a brand to me. The bolts are zinc-plated not stainless.

I just want to be sure they are the right grade for the job. I know the old saying is, "If you can't read a grade marking, always assume a bolt is Grade 2 or less to be safe."

But I thought I'd post up a pic in case someone is familiar with this brand of bolt and can shed some light on the strange head markings?

The most common grade marking system seen on Imperial size hex bolt heads is the US ASTM/SAE scheme, which is an ANSI Standard. Metric bolts use the ISO 'x.y' numerical grade markings.

These markings don't resemble any in these schemes, so I'd say Grade 2 at best.

Thanks Gadge, In the old days I recall letter codes were sometimes used for sizes. A letter code "L" was for a 7/16" nut or bolt. But my bolts obviously have nothing to do with that system either, as they are M10.

I think you're clutching at straws trying to make that L read as a 1. Look like elcheapo hardware store bolts to me.

L, Grade 1, Grade 2. Hardly matters. If they are el cheapo then they must be Grade 1 or 2, eh?
Thank you for commenting anyway!

Appears to be manufactured by CHUN YU WORKS & CO., LTD. or at least that is closest I can find in the US Department of Defense Handbook 2011 version but I think they are a Lion logo now.

No grading marks so as aussietrev said appears to be el cheapo bolt. If looking for grade 5 or 8 stick a bolt with known grade stamp.

The markings in the middle of the bolt head are the logo for the brand. They are "Zenith" brand bolts and are definitely not high tensile.

Tnx BigTed I couldn't find that logo and was going on the L symbol. Zenith wasn't even listed as manufacture so the US Military handbook dated 2011 on fasteners is out of date apparently.

Ah ha, that's it! Zenith, I can see that now. Thanks for the great info.
I just realized that these are not M10, they are actually 3/8". Not that this makes any difference. An el cheapo bolt is still an el cheapo bolt, regardless of the size!