Gary,
These were stainless steel wires inside protective polymer
sheathing, extra thick multiple coatings.
The wires were mounted on a "fence" and then placed under
tension to make their resonance from wind, etc fairly high
frequency - like the e string on a bass guitar.
Seems the tension put so much internal stress into the
wires and encouraged so much corrosion that the wires would
only last a year, even 2 miles from an ocean.
- Robert -
On Fri, 10 Oct 2003 14:56:39 -0700
"GARY MCINTURFF" <[email protected]> wrote:
> Robert,
> Thanks for the info. Do you mean stress from normal
> nut/bolt torque or from a press-fit application. Here is
> another small tidbit you might consider - a trick I got
> from an aircraft mechanic. Even if the part is stainless
> steel if you are working around it with non-stainless
> tools you can compromise the stainless part with the
> tool. It is the tool material that could be starting the
> corrosion. In the particular instance I was discussing it
> was stainless steel panels that were being sheared, and
> the shear didn't have stainless "shoes" or whatever the
> actually shearing components are. These shoes smeared
> onto the stainless parts and viola corrosion. When they
> put stainless shoes on the shear the problem disappeared.
> This was a Boeing 747 crew chief so he certainly has
> the experience to make him believable. Might want to
> check your manufacturing plant just for grins.
> Gary
> ----- Original Message -----
> From: robert Macy
> To: GARY MCINTURFF ; [email protected]
> Sent: Friday, October 10, 2003 12:01 PM
> Subject: Re: Corrosion tests - NEBS or Milspec
> acceleration factors?
>
>
>
> Gary,
>
> From experience with security systems only "close" to
> the
> seashore (approx 2 miles away) it is best to *NEVER*
> have
> any of the metal parts under stress/tension, else the
> corrosion rates are incredibly accelerated.
>
> The particular stainless steel part had been tested
> real
> time in worse environments with absolutely no
> degradation
> detectable. Yet, in the actual application under
> mounting
> stress the stainless steel part repeatably failed
> within 1
> year even that far away from the ocean.
>
> - Robert -
>
> Robert A. Macy, PE .. [email protected]
> 408 286 3985 . . . .. . . fx 408 297 9121
> AJM International Electronics Consultants
> 101 E San Fernando, Suite 402
> San Jose, CA 95112
>
>
>
> On Fri, 10 Oct 2003 09:47:40 -0700
> "GARY MCINTURFF" <[email protected]> wrote:
> > Ernie,
> > I know you received Naftali's email so I will
> just
> > clarify a little more. We test and pass the GR-487
> > outdoor enclosure requirements for the
> telecommunications
> > industry but I have a client who is non-telecom.
> > Telecommunciations customers seem to accept the test,
> > because past experience has shown in meets the
> equipment
> > and time needs (20 years). Non-Telecommunications
> > customers not familiar with the tests kind of expect
> some
> > sort of acceleration factor for the hours under test
> to
> > demonstrate how long the equipment will work, rather
> than
> > a more or less pass fail salt fog test. He wants to
> how
> > long the equipment can withstand the elements at his
> > coastal location. Is there any sort of acceleration
> model
> > used in the salt fog test, or the mixed gasses and
> > hygroscopic tests? He is a little unhappy with my
> > current response (understandably) that experience
> shows
> > the test satisfies the screening requirements or else
> > they would have been changed long ago to something
> that
> > did meet the equipment and time requirements.
> > Can you give me a little insight?
> > Thanks
> > Gary McInturff
>
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