Conduit RMC- argument

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rounder22

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ok guys here goes, I recently ran across an electrician whose hydraulic bender was broken. He was using a torch to heat and bend a 90 on a 2.5" stick of rigid. I told him that it was a code violation. He said to prove it. His argument was the code said as long as one doesn't change or deform the conduit it was ok. So far I haven't found anything to disprove his argument. I was under the impression that once conduit was heated,such as in a burnt building, it was no longer usable. :confused:
 
Re: Conduit RMC- argument

I'm not even sure you are prohibited from deforming it. Clearly just bending conduit causes at least some deformation.

The main issue I would think is that the heating would damage the varnish coating on the inside of the conduit or the zinc galvanizing on the outside. Tell him to prove he has not damaged the inner coating by heating the exterior of the conduit.
 
Re: Conduit RMC- argument

I'm thinking that what he is doing may violate 110.3(B), i.e violate the listing of the conduit. Not sure if 344.24 applies. (all references from 2002 NEC)
 
Re: Conduit RMC- argument

344.24 Bends ? How Made. Bends of RMC shall be made so that the conduit is not damaged and the internal diameter of the conduit is not effectively reduced. The radius of the curve of any field bend to the centerline of the conduit shall not be less than indicated in Table 344.24.
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I hesitate being another engineer addressing this issue; I?d much prefer that one of our inspector or electrician colleagues answer it. But, since an EIT asked the question, I?ll at least speak to it from an EE perspective.

Section 344.24 definitely applies and it addresses both issues of deforming (the internal diameter cannot be reduced) and damage. The steel used for Ferrous Metal Conduit is ?soft? malleable. That?s why it bends ?relatively? easily. While 300.18(B) generally prohibits welding raceways, it doesn?t specifically prohibit ?torching? them to bend them; however, in my opinion any discoloration of the galvanizing is evidence that the RMC is damaged. I?d also run a nylon stocking through the bend and any evidence of it catching also would be sufficient to reject it.
 
Re: Conduit RMC- argument

I can't speak to the listing issue. I'm having a problem using the UL website, but I would look for whether the conduit is listed to be bent with a bender or if bending is even mentioned in the guide info.

The galvanizing damage won't be a problem in a dry location. If outdoor, then paint or spray on galvanizing.


Bob
I'm curious. What are you looking for with the stocking, cracks in the metal? Cracks would be cause for rejection.

Inspectors should be loking for minimum compliance and although some may think it a stretch, this scenario could be ok.
 
Re: Conduit RMC- argument

I wouldn't put a torch to anything galvanized in a confined space.
Make sure there is plenty of ventilation.
 
Re: Conduit RMC- argument

Originally posted by sandsnow:
I can't speak to the listing issue. I'm having a problem using the UL website, but I would look for whether the conduit is listed to be bent with a bender or if bending is even mentioned in the guide info.

The galvanizing damage won't be a problem in a dry location. If outdoor, then paint or spray on galvanizing.


Bob
I'm curious. What are you looking for with the stocking, cracks in the metal? Cracks would be cause for rejection.

Inspectors should be loking for minimum compliance and although some may think it a stretch, this scenario could be ok.
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Larry, I sincerely appreciate your practical and thoughtful approach to inspection.

There is no UL restriction beyond what the Code already says - that's one reason I wouldn't reject it outright either. But I definitely would want to be certain there was no internal damage. Part of the problem is that enough heat to "blue" the galvanizing changes its chemistry and there is no direct way to tell how severe the effects are especially deep inside the conduit. But if the conduit's outside finish were "clear" and there was no evidence of internal damage, I might accept it too. I'd also look closely for any potential "flattening" through the bend.
 
Re: Conduit RMC- argument

Bob
Thanks.

Hey rounder22
Just how long did it take to bend that masterpiece?? It must have been some very extenuating circumstances.
 
Re: Conduit RMC- argument

That pipe more than likely made a trip to the universal die via a bandsaw first,and spawned little 2.5"s pipes..
 
Re: Conduit RMC- argument

Originally posted by rounder22:
[QB]
Originally posted by tom baker:
[qb] Is this a proposal for the 2008 NEC to prohibit torch heating for bending?
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No its not, I guess if your in a bind and your way behind one crappy bend may not kill us. Hey that kinda rimes......

thx
Rounder
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Re: Conduit RMC- argument

Originally posted by sandsnow:
Bob
Thanks.

Hey rounder22
Just how long did it take to bend that masterpiece?? It must have been some very extenuating circumstances.
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It was a rush shut down job. It only took a few minutes...I think he has mastered the art of bending pipe.
:D
 
Re: Conduit RMC- argument

:confused: Yes. I too would love to hear the precise method of conduit bending via torch. Unless it was just a tweak I cannot imagine how the conduit was prevented from flattening in the radius. I've done some novel conduit bending over the years (trees, semi trailer tires, etc) when in a pinch but never resorted to the blacksmith method.
 
Re: Conduit RMC- argument

for the overheating of the 110 citing to have any merit, thr part nmust be broken, bent (where it wasn't before, otherwise no bent pipe), cracked or deteriorated. pipe should be able to be heated and bent where it doesn't damage the integrity of the interior surface , or the integrity of the pipe structure. mild malleable steels are heated and reheated without losing their strength. These are not alloys, tempered, cold-rolled, or other altered metals.

The two primary concerns are corrosion resistance and deformation. I guess spray on galvanizing would not satisfy the purists.

paul :)
 
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