Field Bend

[Alwayslearningelec]

Would you ever field bend 4" PVC Coated RGS or always use prefab? Have about 250 bends within multiple sets.

It's all on a roof on ground and not up in air, not sure if that makes difference in determing whether bend or use prefab.

 

[infinity]

Either way will work. I would probably lean towards prefab.

 

[don_resqcapt19]

Yes, factory 90s.
It would probably take special shoes and follow bars to field bend, but that will still likely be a problem for any kicks or offsets that are needed.
If the conduit was smaller, I would probably just use the next larger shoe and follow bar, but with many benders, they stop at 4", so you can't do that.

 

[Alwayslearningelec]

Yes, factory 90s.
It would probably take special shoes and follow bars to field bend, but that will still likely be a problem for any kicks or offsets that are needed.
If the conduit was smaller, I would probably just use the next larger shoe and follow bar, but with many benders, they stop at 4", so you can't do that.

Yes but then don't you then need to cut and thread whihc adds labor?

 

[infinity]

Yes but then don't you then need to cut and thread whihc adds labor?

Correct prefab 90's require more couplings and nipples but they are often less time consuming than bending. Also prefab 90's are easier to spin on.

 

[don_resqcapt19]

Correct prefab 90's require more couplings and nipples but the is often less time consuming than bending. Also prefab 90's are easier to spin on.

Especially with the extra care needed for PVC coated RMC.

 

[don_resqcapt19]

If they have specified PVC coated rigid, what did they specify for the supporting straps and struts?

 

[Alwayslearningelec]

Correct prefab 90's require more couplings and nipples but the is often less time consuming than bending. Also prefab 90's are easier to spin on.

EASIER to spin on??? Than what? You would be field bending otherwise.

 

[don_resqcapt19]

EASIER to spin on??? Than what? You would be field bending otherwise.

A field bend will be much longer on one end than a factor bend would be.

 

[infinity]

EASIER to spin on??? Than what? You would be field bending otherwise

I know we've been down this road before but a prefab 90 is about 32" long on each end. An elbow bent somewhere on 10 foot length of pipe is 10' of weight that you have to try and spin on instead of maybe 48" of pipe.

 

[Alwayslearningelec]

I know we've been down this road before but a prefab 90 is about 32" long on each end. An elbow bent somewhere on 10 foot length of pipe is 10' of weight that you have to try and spin on instead of maybe 48" of pipe.

 

[electrofelon]

just curious because I have never worked with it: How thick is the PVC coating? Does it get damaged when you field bend it? Is there a coating that you field apply at the couplings and/or any damaged areas?

 

[roger]

Does it get damaged when you field bend it? Is there a coating that you field apply at the couplings and/or any damaged areas?

Sometimes and yes. The couplings and connectors have an additional length of the PVC on each end to overlap the pipe

 

[quantum]

Our field crews mostly field bend with Greenlee 884s or 885s. We do use coated shoes for the PVC/RGS.

 

[don_resqcapt19]

just curious because I have never worked with it: How thick is the PVC coating? Does it get damaged when you field bend it? Is there a coating that you field apply at the couplings and/or any damaged areas?

There is, but unless you apply multiple coats, you won't have good corrosion protection.

 

[electrofelon]

There is, but unless you apply multiple coats, you won't have good corrosion protection.

So I guess I don't understand how this stuff is installed. I can see how the factory lengths can be made so the PVC butts up to the previous piece. But what do you do when you need to field cut a piece?

 

[quantum]

just curious because I have never worked with it: How thick is the PVC coating? Does it get damaged when you field bend it? Is there a coating that you field apply at the couplings and/or any damaged areas?

40 mil exterior, thinner on the interior. It does not get damaged if the correct tools are used, i.e. coated bending shoes, the appropriate adapters for chain vices, and strap wrenches/fine tooth pipe wrenches. Robroy and Ocal also sell touch-up paint that can be used to field repair the coating on their products.

 

[don_resqcapt19]

So I guess I don't understand how this stuff is installed. I can see how the factory lengths can be made so the PVC butts up to the previous piece. But what do you do when you need to field cut a piece?

You need special teeth in you threader and you cut the coating length wise about 1/4" apart for the length of the threads before you thread it.
The threads, even on the factory lengths are not coated. The couplings have sleeves that extend a couple of inches past the coupling at each end and the sleeves are a vert tight fit to the OD of the coated conduit.
Video instructions for one brand of PVC coated conduit. If you notice the inside of the conduit is also coated.

 

[muddyboots]

I was always under the impression that the threads also require a kind of sealant that the manufacturer provides (may be the same as the touch up paint, it's been a few years since I had to run pvc coated rmc).
I do remember cursing at myself once or twice with a bad measurement or an offset/90 not quite turned the right way. After about 20 seconds the sealant seems to cure and after that, good luck getting it to spin on or off anymore. Would have to cut off and start over which in my experience means having to completely redo on a fresh stick.
I am not sure if this is a requirement from the manufacturer or possibly an engineering spec, but it definitely can turn into a pain in the tail. But as others have explained having the proper tooling and adapters is crucial for a smooth installation. They also make specialized channel locks that are great for smaller pipe, strap wrenches generally work good in larger stuff.

 

[quantum]

I was always under the impression that the threads also require a kind of sealant that the manufacturer provides (may be the same as the touch up paint, it's been a few years since I had to run pvc coated rmc).
I do remember cursing at myself once or twice with a bad measurement or an offset/90 not quite turned the right way. After about 20 seconds the sealant seems to cure and after that, good luck getting it to spin on or off anymore. Would have to cut off and start over which in my experience means having to completely redo on a fresh stick.
I am not sure if this is a requirement from the manufacturer or possibly an engineering spec, but it definitely can turn into a pain in the tail. But as others have explained having the proper tooling and adapters is crucial for a smooth installation. They also make specialized channel locks that are great for smaller pipe, strap wrenches generally work good in larger stuff.

That would be news to me. Ocal requires or recommends KopR-Shield. Requesting touchup coating sounds like a customer or engineering preference. STL8 is the only thing we use unless a customer spec says otherwise. We do have one customer that requests we coat the couplings after install with touch-up paint. They think it water proofs the install lol.