Counterfeit Fasteners
In the past two years a great deal of concern and publicity
about counterfeit fasteners has surfaced. The counterfeit case
with the most documentation is the deliberate marking of
grade 8.2 boron bolts as grade 8 bolts.
Grade 8.2 bolts are a low-carbon (0.22 percent C) boron
alloy steel that can be heat treated to the same roomtemperature
hardness as grade 8 medium-carbon (0.37 percent
C) steel. However, the room- and elevated-temperature
strengths of the grade 8.2 bolts drop drastically if they are
exposed to temperatures above 500 OF. Grade 8 bolts can be
used to 800 OF with little loss of room-temperature strength.
Other fasteners marked as MS and NAS but not up to the
respective MS or NAS specification have shown up; however,
documentation is not readily available. Since these fasteners
are imported and have no manufacturer's identification mark
on them, it is not possible to trace them back to the guilty
manufacturer. U. S . Customs inspections have not been
effective in intercepting counterfeit fasteners.
Another problem with fasteners has been the substitution
of zinc coating for cadmium coating. If a dye is used with the
zinc, the only way to detect the difference in coatings is by
chemical testing.
Federal legislation to establish control of fastener materials
from the material producer to the consumer is being
formulated.Regards, Harold Sprague
> Date: Thu, 26 Nov 2009 07:39:34 -0500
> From: design@hodgsoneng.ca
> To: seaint@seaint.org
> Subject: Re: Grade 8 bolt properties
>
> I deal with ferro-manurium almost every day and some of it involves
> engineering.
> Gary
>
> Christopher Wright wrote:
> >
> > On Nov 24, 2009, at 6:58 AM, Gary L. Hodgson and Assoc. wrote:
> >
> >> I have one customer who keeps wanting to use the nice shiny SAE grade
> >> 8 bolts because they look better than those black A325 or A490 bolts.
> > To make things worse, the Counterfeit Bolt Affair of the 1990's hasn't
> > gone away. If anything it's gotten worse.
> > <http://www.nv.doe.gov/library/publications/sitelines/sl100.pdf> The
> > original problem was with so-called grade 8 bolts that were actually
> > grade 8.2 (or something like it) that were understrength or wouldn't
> > hold a pre-load. So when you go through all your spec options keep in
> > mind that you could be getting ferro-manurium fasteners if you don't
> > shop with care.
> >
> > Christopher Wright P.E. |"They couldn't hit an elephant at
> > chrisw@skypoint.com | this distance" (last words of Gen.
> > .......................................| John Sedgwick, Spotsylvania
> > 1864)
> > http://www.skypoint.com/members/chrisw/
> >
> >
> >
> >
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