I can answer part of your questions.
The bolts with 6 hash marks are Grade 8, the highest grade and strongest
generally available.There are markings on the nuts, as well, but I'm not
sure how to describe them: a dot, a hash mark and a percent sign, sort
of. Ask at a hardware store for a sample. Grade 8 will handle the
highest torque.
The bolts with 3 hash marks are Grade 5. This is a moderately strong
bolt.
Bolts with no markings are ungraded and the weakest of the bunch, most
likely to fail under stress and can take the least torque.
Tony Rhodes wrote:
> I know that nuts and bolts come in various grades.
>
> How do you differentiate them by sight? I have seen some
> bolts with lines on the top. Usually I have seen 3 lines or 6 lines.
> These lines are aligned radially pointing to corners. Many
> bolts I see have no markings. I have never noticed any
> particular markings on nuts. How do you tell grades there?
>
> In a similar vein, gow do you differentiate grades of
> torque wrench sockets. I have seen some with
> no circumferential lines, others with one or two. Do
> these have any meaning?
>
> -Tony
> ARhodes@compuserve.com
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MZ
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