Bending an Offset in 1" PVC

[Anthony Whitesell]

Based on our wonderful sticky thread for bending conduit, I need to install some 1" PVC with some box offset bends (slightly larger than the standard offset). Two questions:

1) How do you calculate how much and where to make each of the bends?

2) What tools do you suggest for bending PVC? I am hoping to only have to make two of these offset bends in the run.

[Chris Padilla]

I know that offset bends are available in 1/2" and 3/4" but I haven't seen any for 1".

To bend PVC you need a hot air gun. Not a hair dryer...but a nice hot air gun. Once you get the PVC soft enough, you can bend it however you like.

You can even save PVC fittings and remove the glued-in pipe by heating it up and working out the pipe. Try some searching on "bending PVC" and you'll hit a plethora of videos on YouTube that you should find interesting.

This one looks interesting...no heat required: CLICK

[Anthony Whitesell]

Home Depot has a pre-made 1" offset bend, Lowe's does not. Go figure. Unfortunately, the offset is not large enough.

I do have a real heat gun. I'm most interested in the first part, how to calculate the bend angle and spacing to achieve the right offset. I doubt I will get two chances at it with PVC conduit.

[John Lanciani]

Heat up the last 6-8" of conduit until it is pliable and install it. No calculations required, it finds its own fit.

[Chris Padilla]

^^^^^^^^^^^^^^EXACTLY. Heat and install it.

[Steve Peterson]

In a pinch, you can always cut a 90 degree sweep in the middle and rotate one end to put it back together as an offset bend.

Steve

[Buck Williams]

I'm not quite sure what your install looks like, you can often use a *(trade name) Minerallac conduit hanger as a kind of a stand-off so that you can run your conduit straight in to the 1" KO in the box.

Example Link - http://www.cesco.com/b2c/product/Min...-and-Nut/73486

Screw the hanger into the wall through the hole in the top of the clamp, and it should be close to a straight shot into knock out on the box.

[Anthony Whitesell]

In short I need to connect an PVC LB to a PVC junction box (http://www.lowes.com/pd_115862-223-E...d=1005247&pl=1) after coming through the foundation. The LB sits proud of the foundation but the length of the hub and the junction box is mounted flush to the foundation. The distance from the foundation to the LB outlet headed to the box is more than the standard box offset to transition from a flush mount Lx or T fitting to the box, So I will need to bend my own offset. Further downstream and upstream will not be an issue, only at the transitions through the foundation.

[Wade Lippman]

I know that offset bends are available in 1/2" and 3/4" but I haven't seen any for 1".

To bend PVC you need a hot air gun. Not a hair dryer...but a nice hot air gun. Once you get the PVC soft enough, you can bend it however you like.

You can even save PVC fittings and remove the glued-in pipe by heating it up and working out the pipe. Try some searching on "bending PVC" and you'll hit a plethora of videos on YouTube that you should find interesting.

This one looks interesting...no heat required: CLICK

It doesn't break!?

[Julie Moriarty]

Bending PVC is usually done in a hot box. It's a rectangular box about 4-5' long, is open on both ends and has roller wheels at each end that the pipe sits on. They are electrically powered and usually 240V. There are coils running the length that heat the pipe and you spin it to make sure it's evenly heated.

I'm explaining that so you get an idea how the process works.

Before bending PVC, you need to plug the ends tightly. The reason is so as you heat the pipe, the air inside expands a little, and when you go to bend it, the pressure inside keeps the pipe from kinking.

I've never used a heat gun but it could work for one bend. You would have to spin the pipe or make sure the gun heats the entire circumference for a length sufficient to give you the bend you need. I would say that means something close to a foot would have to be evenly heated before attempting to bend it.

The second bend might be trickier because the pipe is no longer straight, but the goal is the same. Heat all around the pipe until it becomes soft and bend.

To set the bend, drench the pipe with water. A wet rag works just as well as long as it's very wet. No formulas are needed. If you need a very specific bend, you can make a template for the bend to follow. We usually use pipe but anything formable will work.

[Anthony Whitesell]

One of the you tube videos, uses a spring to maintain the ID (instead of plugging the ends).

[Rollie Meyers]

A heat gun, propane torch, even stuffing the PVC up a vehicles exhaust pipe can soften the pipe to bend it, it's real easy to scorch the pipe when a torch is used, the downside is that the NEC requires that it only be bent by "identified bending equipment" per 352.24. After a bend is made, a wet rag will "set" it.

[Julie Moriarty]

Never tried the car exhaust method but have used the exhaust from a backhoe to heat the pipe. Because you're holding it in your hands, once the pipe gets soft, you have to be really careful not to let it kink.

The first job I worked on as an apprentice had one of these:

You fill it with some kind of liquid and insert the pipe in the top. The contractor bought it new for that job because we had miles of PVC to lay and he thought it would save time. It did just the opposite. The journeymen on the job had nothing good to say about it and then one day a beat up old version of this showed up on the job.

We used it for the remainder of the job.

But in a pinch, you find any good heat source and make do.

[Art Mann]

I tried bending some 3/4 inch water pipe using a heat gun once and the result was not satisfactory. The pipe started to collapse at the bend. I think Julie's suggestion of sealing the ends so the pipe doesn't collapse is really clever.