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Re: Steel corrosion

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Jack,

	Another possibility is that the fabricator substituted material in
stock for what was specified.

				Regards,

				H. Daryl Richardson

Balmer James wrote:
> 
> I think it could be explained by the permissible variations in plate
> thickness.  It doesn't sound reasonable that plate would have been produced
> to a thickness tolerance tighter than what you measured.
> 
> I would look into ASTM Spec A6 prior to 1951.  There is a table that lists
> the permissible variations in plate weight.  I would think that the weight
> permissible variations would translate into permissible thickness
> variations.  From this you could determine what the maximum possible
> thickness the plate could have been.  If this max is still less than what
> you measured, you need a crustier engineer.
> 
> James Balmer
> 
> -----Original Message-----
> From: Jack Creviston [mailto:jcreviston(--nospam--at)tlf-engineers.com]
> Sent: Tuesday, April 17, 2001 11:01 AM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: Steel corrosion
> 
> I just finished one of those jobs that remind you why you spent all that
> time earning an education.  The only thing worse than foundry jobs: coal
> bunker inspections!  Both were built around 1951.  The steel in one bunker
> was never painted and is severely corroded (delaminated to less than 50% of
> original cross section).  The other bunker was painted at one time and
> herein lies the mystery.  The steel was cleaned as aggressively as possible
> and then measured with a micrometer.  My measurements are showing the steel
> in be an average of 0.01" thicker than it was 50 years ago.  The steel had a
> pitted appearance, which I attribute to the paint.  My question is: can the
> paint, in this type of environment, "fuse" with the steel?  What I mean is,
> can it become indistinguishable after so many years of acidic exposure?
> Could the extra material be the paint?
> 
> The steel was all solid in this bunker, so my interest is more out of
> curiosity than concern.  I would appreciate any (readily available)
> references or even anecdotal evidence from some of you crustier (I mean that
> with respect) participants.
> 
> Thanks!
> Jack Creviston, EIT
> 
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