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#106782 01/21/05 07:13 PM
Joined: Oct 2000
Posts: 3,661
Likes: 1
Admin Offline OP
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Quote
What tape, I don't see no stinkin tape!

(submitted by Joe Tedesco)
[Linked Image]

2017 / 2014 NEC & Related Books and Study Guides
#106783 01/23/05 09:04 PM
Joined: Dec 2004
Posts: 23
D
Member
what is the story here

#106784 01/24/05 12:28 PM
Joined: Jun 2001
Posts: 642
N
Member
An old one. Some one ran unprotected metal conduit under ground and mother nature has taken her toll. This needs to be fixed now hopefully before some one gets hurt.


ed
#106785 01/24/05 10:34 PM
Joined: Apr 2001
Posts: 518
J
Member
What we need to remember is that materials need to be suitable for their application/environment, regardless of listing.
EMT may be allowed for use underground, but it has shown itself totally inadequate for alkaline soils. Would wrapping it in pipe wrap tape help? I don't know.
I'm a HUGE fan of running pipe, rather than UF cable...but sometimes you have to "look beyond the book."

#106786 01/25/05 10:15 AM
Joined: Mar 2002
Posts: 360
T
Member
Hey John, et al. A lot of the time in a situation like this it's just the transition that rusts through, the O2 in the air leading to the oxidation of the pipe. Would it be money ahead to put in a short, 2' length or so of stainless steel in this instance? I've often thought about that as we have lots of places around here that are on there way to doing the same thing.

TW

#106787 01/25/05 04:16 PM
Joined: Apr 2002
Posts: 2,527
B
Moderator
I understand that tendencies for electrochemical corrosion exist where moisture (as the electrolyte and typical schedule-40-dimension} raceway passes from soil to air, concrete to air or soil to concrete. It is murderous with aluminum pipe, and much less so for brass {$$} or nickel-chromium {$$$} raceway alloys. The UL white books stress this under the phrase, “supplementary protection.”

In extreme cases where soil is strongly alkaline (high pH) there are asphaltic-based (versus vinyl) tape/mastics that are applied to many types of subsurface metallic piping, For thousands of hard-core situations {like $1M/hour-leaking cross-country 30-inch oil line} the coating durbility can be effectively enhanced with judiciously applied sacrificial anodes driven with DC excitation—looking like stone-age golfcart battery chargers.

Soil resistivity {1/conductivity} varies all overr the place, directly affecting corrosion rates.




[This message has been edited by Bjarney (edited 01-25-2005).]

#106788 01/25/05 10:33 PM
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
Sure, Train, I agree. Heck, even stubbing down with RMC is an improvement. The "code" problem arises when you try to buy SS, Brass, or whatever conduit- as far as I know, no "listed" product exists. I've done it, but you can't rely on the inspector exercising judgement.

Of course- there's always plastic pipe! And, with corrosion being an issue, maybe a ground wire isn't a bad idea either.

#106789 01/26/05 08:40 PM
Joined: Dec 2000
Posts: 4,287
Member
[Linked Image] WELCOME RENOSTEINKE [Linked Image]

John, could that be GRC in the picture?


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