bending large PVC conduit

[pr3dict]

I've heated up 1 inch and 1 1/2 inch conduit with a heat gun before but this 2 1/2 sch 40 is like a rod of steel.

I've seen this thing called a pvcbendit for sale for $400 but that's a little steep. A sunbelt rental place an hour away from me has some PVC oven type thing that looks like it would do the trick but I don't want to drive 4 hours (1 each way twice) to pick it up and delivery/pickup is $300.

Any other ideas? I need to make what essentially is a 90 degree angle over a fairly large radius.

 

[Kevin Essiambre]

A heat gun and a piece of duct work underneath the PVC to circulate the heat around the pipe. It will take awhile to heat up (I do 2" PVC all the time. For a long radius you'll want something to sit on). You may have to do it one section at a time (something like 8" segments at a time).

I'll admit that I've used a BBQ and propane heaters to bend PVC too, but they aren't approved methods of bending PVC where I am haha

 

[pr3dict]

A heat gun and a piece of duct work underneath the PVC to circulate the heat around the pipe. It will take awhile to heat up (I do 2" PVC all the time. For a long radius you'll want something to sit on). You may have to do it one section at a time (something like 8" segments at a time).

I'll admit that I've used a BBQ and propane heaters to bend PVC too, but they aren't approved methods of bending PVC where I am haha

I guess I'm more afraid that it's going to cave in on itself.

 

[Norcal]

A heat gun and a piece of duct work underneath the PVC to circulate the heat around the pipe. It will take awhile to heat up (I do 2" PVC all the time. For a long radius you'll want something to sit on). You may have to do it one section at a time (something like 8" segments at a time).

I'll admit that I've used a BBQ and propane heaters to bend PVC too, but they aren't approved methods of bending PVC where I am haha

They are not approved here either. A heat gun will work but will take a while, used a weed burner on some 2 1/2”, even managed to avoid scorch marks.

 

[Innovate1]

I used steam to bend up to 1.5" conduit pretty easily. Don't see why it wouldn't work for larger. Just used a plain old "teakettle" and used a 2" piece of PVC about 5 feet long. Put a fitting on the end to reduce the size to loosely fit the teakettle spout. Sloped the pipe slightly up away from the teakettle. Get the water boiling so there is steam going through the pipe. I found just a small flow was enough. Stick the pipe to be bent in for about 3 minutes and it is very flexible. With 2.5" you will need a helper or some blocks to hold one end as you bend it. And probably more time to heat it. I layed out the radius on the floor ahead of time. Wear leather gloves for the hot pipe. Pull it out and quickly bend as needed and hold for a few minutes to cool. Figure on at least a foot or two extra on the ends for leverage. You can throw a coupler on the hot end to hold it round after you pull it out of the heater. Rotate the pipe occasionally during heating so it heats evenly.

When you pull it out if it doesn't seem flexible enough put it back in for a bit more time as you can't reheat it this way once it is bent. I noticed the end sticking out of the heater starting to droop and gave it a little more time after that.

You will need to scale this up. at least 3" pipe to hold the 2.5" , maybe bigger. And you may need longer. You can figure the length along the radius you want.

The outer pipe sagged a bit during the bending and may be worse for longer. I suggest you put a 2x4 under the larger pipe for support. I used a step ladder to support the far end of the steam chamber pipe.

 

[Shiftless]

I bent some half inch by filling it with sand heated in an oven to 350 F.
I filled the pipe with hot sand and then bent it into the shape I needed. One advantage of this technique is that the sand prevents kinking and you’ll never get scorch marks.
Use a big metal funnel and cap off one end.

 

[loganb]

To prevent the collapse I've heard people fill them with sand and tape the ends. Couple co-workers used the sand trick when the did some bends for low voltage cabling at their church, but I wasn't part of the fun so no personal experience.

In the metal bending arena, filling aluminum extrusions with sand to enable stretch bending without significant change in exterior profile is a common practice

Sent from The Garage Journal mobile app

 

[pr3dict]

I bent some half inch by filling it with sand heated in an oven to 350 F.
I filled the pipe with hot sand and then bent it into the shape I needed. One advantage of this technique is that the sand prevents kinking and you’ll never get scorch marks.
Use a big metal funnel and cap off one end.

HAh I like that idea. It's not too much volume either so a large pot should hold enough sand and I could put it in the BBQ oven.

 

[Jim greengo]

I heat electrical PVC conduit over an electric stove all the time,not a big deal.

 

[cybrdyke]

I've heated up 1 inch and 1 1/2 inch conduit with a heat gun before but this 2 1/2 sch 40 is like a rod of steel.

I've seen this thing called a pvcbendit for sale for $400 but that's a little steep. A sunbelt rental place an hour away from me has some PVC oven type thing that looks like it would do the trick but I don't want to drive 4 hours (1 each way twice) to pick it up and delivery/pickup is $300.

Any other ideas? I need to make what essentially is a 90 degree angle over a fairly large radius.

Let Cantex make it for you.
https://www.cantexinc.com/products/elbows-bends

 

[Innovate1]

I guess I'm more afraid that it's going to cave in on itself.

I did 24" radius and didn't have any trouble with collapsing or kinking. Even heat helps keep the bend even. If I was doing shorter bends I think it would have been an issue.

 

[Shiftless]

HAh I like that idea. It's not too much volume either so a large pot should hold enough sand and I could put it in the BBQ oven.

It will take a really long time to heat through in a pot. I used a shallow aluminum tray in the kitchen oven, if the sand is clean, you shouldn’t get in trouble with your S.O.

 

[The Cobbler]

an electrician friend of mine used to heat the pipe with is truck exhaust using an exhaust tube from a repair shop

 

[Dagny]

salamander heater

 

[alfredeneuman]

I bent some half inch by filling it with sand heated in an oven to 350 F.

Half inch PVC can be bent cold with a (3/4" EMT-1/2" Rigid) hand bender.
It springs back so you only get about half the bend you would regularly get (a 90 ends up being a 45) so you have to do it in segments if you any more than a 45

 

[dogdog]

Hot sand / cold water bath?

 

[larry4406]

There are expensive commercial units. Maybe these can give your some ideas/

https://www.greenlee.com/us/en/heat-boxes

 

[sparky 1971]

This will take most of the fun out of it, but why not just buy one at a supply house? That's what I do for larger than 2", I have a hot box for 2" and smaller. A Cantex 36" radius 2-1/2" 90 part number is 5133857. It should cost about $25.00. I checked my contractor pricing and it's $13.81, but it's also out of stock at the sh I use right now. I plead the 5th on whether I have used a weed burner before.

 

[Git]

click the pic for YouTube video

 

[Shiftless]

Half inch PVC can be bent cold with a (3/4" EMT-1/2" Rigid) hand bender.
It springs back so you only get about half the bend you would regularly get (a 90 ends up being a 45) so you have to do it in segments if you any more than a 45

Thanks for the tip. The bend I did had to have about a 12 inch radius.

 

[pr3dict]

This will take most of the fun out of it, but why not just buy one at a supply house? That's what I do for larger than 2", I have a hot box for 2" and smaller. A Cantex 36" radius 2-1/2" 90 part number is 5133857. It should cost about $25.00. I checked my contractor pricing and it's $13.81, but it's also out of stock at the sh I use right now. I plead the 5th on whether I have used a weed burner before.

I need to make a 90 over like 20 feet. I'd need like 6 15 degree elbows to make that turn

 

[nadogail]

Not knowing how many 2.5" conduit bends are needed and the experience of the OP, maybe the better choice would be Premade bends.

 

[pr3dict]

This is what I'm working with.

 

[Movover]

Start one end in the trench and use a weed burner on low, take your time and form it into the trench as you go. Probable need 2 people

 

[johnnyradiant]

Start one end in the trench and use a weed burner on low, take your time and form it into the trench as you go. Probable need 2 people

Now that I see the trench. That's how I'd do it too, or at least it would be my 'Plan A'

 

[pr3dict]

I don't have a weed burner (though I could order one from amazon for $40) but I have a heat gun.... Whats your thoughts on that bad boy?

 

[sparky 1971]

Maybe the picture is deceiving, but it looks like if you were to glue three of four pieces together, they may lay in the trench and form themselves. I know that's what I would be trying first. If that won't work, I believe a weed burner is going to be your next purchase. Home Depot and Lowes carry them, so does Northern Tool. I wouldn't wait for one to show up Amazon. A good rain and you may be trenching again. A heat gun is a waste of time on larger conduit.

 

[larry4406]

I’ve used a heat gun to bend conduit. Mind your distance so as not to burn and rotate while heating as well as heat over a long distance so you don’t ovalize or kink.

 

[oldwino]

Caught an “electrician” pouring About a half a can of PVC glue where he wanted the bend then lighting it. For some reason it was rejected

 

[TonyJ]

About a month ago I needed to do the opposite. I needed to straighten out a 3” sweeping 90 so I used a torpedo heater. Worked like a charm

 

[nadogail]

In the case of the curved trench, which was not disclosed in the Original Post, I would use either brute force and the heat of the sun, or an electric wrap around blanket.

The weed burner, very carefully applied could also work.

 

[MoonRise]

Or retrench it in a straight line from Point-A to Point-B. Then you can use straight conduit and then just two premade 90s at the ends. Done.



Or the $55 propane 'weed burner' at Lowes or Home Depot.

https://www.lowes.com/pd/Lincoln-Electric-Torch-Kit/4742120

Or the slightly less expensive version from HF, $35

https://www.harborfreight.com/propane-torch-with-push-button-igniter-91037.html

Use the 'heat' from the torch and not the flame itself if using the torch method.

 

[pr3dict]

Or retrench it in a straight line from Point-A to Point-B. Then you can use straight conduit and then just two premade 90s at the ends. Done.



Or the $55 propane 'weed burner' at Lowes or Home Depot.

https://www.lowes.com/pd/Lincoln-Electric-Torch-Kit/4742120

Or the slightly less expensive version from HF, $35

https://www.harborfreight.com/propane-torch-with-push-button-igniter-91037.html

Use the 'heat' from the torch and not the flame itself if using the torch method.

Cant go straight as there is a septic/ leach field mound in the way. I'm curving around it in that photo. I'm going to harbor and trying the weed burning method. Seems dangerous but I'm game for a challenge

 

[Innovate1]

I need to make a 90 over like 20 feet. I'd need like 6 15 degree elbows to make that turn

The picture looks like a lot less bend than 90 in 20 feet. You would have a hard time doing 90 in 20 feet cold but the picture looks possible.

 

[pr3dict]

The picture looks like a lot less bend than 90 in 20 feet. You would have a hard time doing 90 in 20 feet cold but the picture looks possible.

My math skills are a little off. Maybe its 40 or 50 feet.

 

[Tduby]

This is what I'm working with.

Damn if you would have done this in August you could have glued it together and let it sit in the sun and made that bend but probably to cold in NJ now.

Like others said glue it up warm it with a burner and lay it in gently.

 

[pr3dict]

Damn if you would have done this in August you could have glued it together and let it sit in the sun and made that bend but probably to cold in NJ now.

Like others said glue it up warm it with a burner and lay it in gently.

Permits... I put my permits in for this in July or June lol.

 

[pr3dict]

On another note.

Thoughts on using a core drill vs a rotary hammer for 3" hole to go through foundation?

 

[MoonRise]

On another note.

Thoughts on using a core drill vs a rotary hammer for 3" hole to go through foundation?

Core drill in a rotary hammer. Bosch SDS-MAX 3-1/4", 12" or 22" length listed.

https://www.boschtools.com/us/en/boschtools-ocs/sds-max-rotary-hammer-core-bits-1-pc--22580-c/#

Or an SDS-Plus 3-1/8" two-piece:

https://www.boschtools.com/us/en/bo...peedcore-thin-wall-core-bits-t3917sc-33867-p/

Biggest 'solid' rotary hammer bit I see on the Bosch site is a 2" SDS-MAX bit.

Although some more looking found a 3-1/8" x 24" Thru-Hole SDS-MAX bit.

https://www.boschtools.com/us/en/boschtools-ocs/sds-max-thru-hole-rotary-hammer-bits-hc6531-29791-p/

Biggest solid SDS-Plus that I see is 1".

https://www.boschtools.com/us/en/boschtools-ocs/sds-plus-bulldog-rotary-hammer-bits-hc2167-27890-p/

Although there is a Bulldog-Extreme 1-1/8" solid bit listed:

https://www.boschtools.com/us/en/bo...g-xtreme-rotary-hammer-bits-hcfc2287-27918-p/

Core bit and done though.

Although you could do the 'drill a whole bunch of smaller diameter holes on the desired circle perimeter and then knock out the center core' approach too.

 

[pr3dict]

Or an SDS-Plus 3-1/8" two-piece:

https://www.boschtools.com/us/en/bo...peedcore-thin-wall-core-bits-t3917sc-33867-p/


Core bit and done though.

Although you could do the 'drill a whole bunch of smaller diameter holes on the desired circle perimeter and then knock out the center core' approach too.

So with that one I just drill in the x" that it goes, clear it, reinsert and keep on going?