NFPA-13 1999 5-13.21 For those areas still using the old code.
----- Original Message -----
From: "Bill Minkel" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, April 20, 2007 11:53 AM
Subject: RE: Underground Dry Pipe
Take a look at NFPA-13 2002 8.14.20
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Todd
Williams
- work
Sent: Friday, April 20, 2007 10:09 AM
To: [email protected]
Subject: Re: Underground Dry Pipe
Methinks you speak from some experience. You kind of eluded to t in your
P.S., but there are different grades of SS. The stuff they would make 4"
pipe out of is most likely a lesser grade than they would use in medical
equipment and would probably start decaying a lot sooner.
My guess is that it would be cheaper to build a new amphitheater than have
4" pipe and fittings made of surgical grade SS.
At 09:23 AM 4/20/2007, you wrote:
Stainless steel does rust, and corrode. Anyone who has owned a sailboat
can attest to that statement. Stainless steel works because the
chromium in the alloy combined with presence of oxygen in the air forms
a passivation layer of chromium (III) oxide. This layer is too thin to
be visible, which accounts for the nice shiny appearance of stainless.
Anything that disrupts that layer, or shields the stainless from direct
contact with oxygen (buried underground) disrupts that reaction. This
accounts for the rust stains that seep out from under stainless steel
cleats, and the corrosion in a nice shiny new stainless steel
turnbuckle that has spent a year or so tightly wrapped in rigging tape.
Stainless steel pipe would probably last a lot longer than either black
steel or galvanized pipe in this application, but not forever.
Actually in the environment described, polyethylene sleeved, cement
lined ductile iron would last the longest. No exposed metal to rust on
the inside and no exposed metal to corrode on the outside. The only
question I would have since I haven't looked into it is the sealing
properties of the gaskets under air verses water pressure.
.Just random thoughts brought on from following this thread.
Richard L. Mote
Designer
Rowe Sprinkler Systems, Inc
P.S. Nickel, molybdenum and vanadium also contribute to passivation and
may be present in varying quantities some grades of stainless steel.
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Todd G. Williams, PE
Fire Protection Design/Consulting
Stonington, Connecticut
860-535-2080
www.fpdc.com
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