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RE: Grade 8 Bolts

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A grade 8 is primarlily a metric grade 8.8 bolt to a DIN standard and is
widely used in structural connections here in Europe. You may be able to get
the correct information from Borstlap who are a very large Dutch bolt and
nut company. They have several depots in the USA. Contact them via
www.borstlap.com 

> -----Original Message-----
> From:	Neil Glaser [SMTP:NGlaser(--nospam--at)pkainc.com]
> Sent:	Monday, February 28, 2000 12:54 PM
> To:	seaint(--nospam--at)seaint.org
> Subject:	Re: Grade 8 Bolts
> 
> This definitely sounds like a fatigue problem and if it is, it will likely
> occur again.  Grade 8 bolts are roughly the equivalent of A490 bolts,
> however,
> they are not typically used for structural applications.  If it is a
> fatigue
> problem, I would assume that the bolts are located within the column
> flanges.
> Due to the beam rotation this would cause large stress fluctuations in the
> bolt
> since the beam will rotate about the column flanges. Short of some type of
> modification to move the bolts outside the column flanges, your best
> option
> would be to recommend frequent inspections and replacement of the bolts.
> 
> Neil J. Glaser, P.E.
> 
> Fountain Conner wrote:
> 
> > I have an long-time industrial client who recently replaced a bunch of
> > *missing* structural bolts with "Grade 8" (I assume SAE, Grade 8) bolts.
> I
> > can only guess what happened to the original bolts.  I'm sure they
> weren't
> > stolen, so that leaves the options of working loose or breaking under
> > repetitive load cycles -- This is a vertical bolt, attaching a crane
> girder
> > to a column cap plate.  Can anyone say, "fatigue"?
> >
> > I'm not comfortable with this replacement.  So far as I can tell, the
> grade
> > 8 machine bolt is hard, tough, and *brittle*.  'Sounds like courting
> > disaster to me...
> >
> > I recommended replacing the *new* bolts with A325, but the client is
> > reluctant to spend money twice for the same work.
> >
> > Guidance and counsel, anyone?
> >
> > Fountain E. Conner, P.E.
> > Gulf Breeze, Fl. 32561
> >
> 
>