Conduit workmanship interpretation

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jtinge

jtinge

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Hampton, VA
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Sr. Elec. Engr
On a current facility construction project, conduit for data and communication circuits was installed having some slight deformations in the bends resulting in differing opinions from the QA inspectors on its acceptability. The spec requirement applicable for this conduit includes the following: "Do not install crushed or deformed conduits." In your opinion, do the deformations in the conduit bends rise to the point of being "crushed" or "deformed"? Would conduit fill margin to maximum allowable fill color your opinion?
 

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My money is one the fact that you're looking at 2" EMT. For whatever reason 2" EMT is notorious for dimpling when field bending. We have had this problem for years with many different sidewinder type benders.

In a perfect world there would be no dimples but IMO they really are not a cause for concern unless the tubing is actually kinked.
 
infinity said:
My money is one the fact that you're looking at 2" EMT. For whatever reason 2" EMT is notorious for dimpling when field bending. We have had this problem for years with many different sidewinder type benders.

In a perfect world there would be no dimples but IMO they really are not a cause for concern unless the tubing is actually kinked.
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Kinda my thought too. Especially if they aren't trying to bump up against the max allowable fill. I wouldn't lose sleep over this one and play my non compliance card for something worth the energy.
 
jtinge said:
Kinda my thought too. Especially if they aren't trying to bump up against the max allowable fill. I wouldn't lose sleep over this one and play my non compliance card for something worth the energy.
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I agree.
 
jtinge said:
On a current facility construction project, conduit for data and communication circuits was installed having some slight deformations in the bends resulting in differing opinions from the QA inspectors on its acceptability. The spec requirement applicable for this conduit includes the following: "Do not install crushed or deformed conduits." In your opinion, do the deformations in the conduit bends rise to the point of being "crushed" or "deformed"? Would conduit fill margin to maximum allowable fill color your opinion?
Click to expand...
Well now, this is interesting. The specs say "Do not install crushed or deformed conduits". The second you bend a conduit, you "deform" it.
As for workmanship, it can not be defined.
There is a huge difference between QA and minimum code standard.

Ron
 
infinity said:
My money is one the fact that you're looking at 2" EMT. For whatever reason 2" EMT is notorious for dimpling when field bending. We have had this problem for years with many different sidewinder type benders.

In a perfect world there would be no dimples but IMO they really are not a cause for concern unless the tubing is actually kinked.
Click to expand...
Thats not 2" in the pic, right? I might be misinterpreting what your saying..
Dimpling on auto benders usually means its emt on a rigid ramp, or on the table benders, the tray is backwards. Have uou tried the "seam" in both the 12 oclock and 6 position?
The dimps in the pic happen because the bend was made by hand in the air.. instead of on the ground with the foot, or with very poor pressure on the foot and too much on the bar.
They kind of did it perfectly backwards...they decreased the center mark instead of increasing...all the kicks should be straight.
But, there aint nothing wrong with those bends.. at least they used pencil...
 
rambojoe said:
Thats not 2" in the pic, right? I might be misinterpreting what your saying..
Dimpling on auto benders usually means its emt on a rigid ramp, or on the table benders, the tray is backwards. Have uou tried the "seam" in both the 12 oclock and 6 position?
The dimps in the pic happen because the bend was made by hand in the air.. instead of on the ground with the foot, or with very poor pressure on the foot and too much on the bar.
They kind of did it perfectly backwards...they decreased the center mark instead of increasing...all the kicks should be straight.
But, there aint nothing wrong with those bends.. at least they used pencil...
Click to expand...
Yes it's probably 2" so it was not bent in the air. Look at the red conduit behind it which appears to be 3/4.
 
hbiss said:
Nothing that, after seeing the first bend, wouldn't make me stop and figure out what I was doing wrong. I wouldn't put my name on that.

-Hal
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You whip these kids in shape then! At least they got something up in a week... Things are bad hbiss.
 
I appreciate all the perspectives on this installation. Another illustration of how vague requirements that aren't measurable lead to various interpretations when checking for compliance.
 
hillbilly1 said:
Ah! Tractor trailer bender! Yeah, need to buy or rent a bender.
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Actually, I have seen this mostly when the squeeze isn't properly adjusted on the bender, but also, especially with 2" with cheap conduit. Anyone ever seen the conduit split on the seam when it is bent? I have, for some reason, 2" is almost always the problem.
 
infinity said:
My money is one the fact that you're looking at 2" EMT. For whatever reason 2" EMT is notorious for dimpling when field bending. We have had this problem for years with many different sidewinder type benders.

In a perfect world there would be no dimples but IMO they really are not a cause for concern unless the tubing is actually kinked.
Click to expand...
Just what I said before I read your post. It is weird isn't it? Bend 2 1/2" and it doesn't have the same problem.
 
rambojoe said:
Thats not 2" in the pic, right? I might be misinterpreting what your saying..
Dimpling on auto benders usually means its emt on a rigid ramp, or on the table benders, the tray is backwards. Have uou tried the "seam" in both the 12 oclock and 6 position?
The dimps in the pic happen because the bend was made by hand in the air.. instead of on the ground with the foot, or with very poor pressure on the foot and too much on the bar.
They kind of did it perfectly backwards...they decreased the center mark instead of increasing...all the kicks should be straight.
But, there aint nothing wrong with those bends.. at least they used pencil...
Click to expand...
All of the things you are saying are valid, but that pic is definitely not hand bent conduit. Again, squeeze adjustment, but also as you pointed out, seam orientation, even in a sidewinder bender can affect that. I don't think I would allow that in my company and I have acted as QC manager in and official position in my company. That is too much ripple for too small of a bend.
 
Strathead said:
Actually, I have seen this mostly when the squeeze isn't properly adjusted on the bender, but also, especially with 2" with cheap conduit. Anyone ever seen the conduit split on the seam when it is bent? I have, for some reason, 2" is almost always the problem.
Click to expand...
Yes we've been having problems with 2" EMT for a decade. We've tried different conduit manufacturers, different benders, different seam orientation, etc. with varying results. Some sidewinder type benders don't have a squeeze adjustment but they bend 1½ and smaller EMT with no problems. The 2" EMT seems to be the common denominator. Yes I've seen EMT split when bending a 90° elbow.
 
jtinge said:
I appreciate all the perspectives on this installation. Another illustration of how vague requirements that aren't measurable lead to various interpretations when checking for compliance.
Click to expand...
Vague and unquantifiable requirements can't be enforced. I don't like how it looks but it is serviceable.
 
infinity said:
Yes we've been having problems with 2" EMT for a decade. We've tried different conduit manufacturers, different benders, different seam orientation, etc. with varying results. Some sidewinder type benders don't have a squeeze adjustment but they bend 1½ and smaller EMT with no problems. The 2" EMT seems to be the common denominator. Yes I've seen EMT split when bending a 90° elbow.
Click to expand...
BUT... That is not a very big angle. It looks less than 30 degrees, and for that much ripple in less than 30 degrees I feel it is too much.
 
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