bending pvc pipe

Discussion in 'HortForum' started by pointy1, Feb 24, 2010.

  1. pointy1

    pointy1 Member

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    Hi. I want to make a row cover for my raised bed using 1/4 or 1/2 inch pvc pipe. My beds are only 36" wide and I'm wondering if PVC pipe will bend that much without heating it. Anyone with experience using PVC pipe out there who can tell me what sort of curve I can get over a 3 foot width. I'm hoping to have enough height so that the curve doesn't compromise the growing space at the edges of the bed.

    I'm going to buy a length on the weekend to experiment, but wondered if there are any known formulas out there. Any suggestions for other cheap and easy materials that might work better?

    Thanks!
     
  2. photopro

    photopro Well-Known Member

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    I've used it for many things but we always have to use the angled joints to make it bend. If he did the pipe simply collapses. My entire overhead watering system was constructed of PVC pipe with farm ministers normally use for tractors and chicken houses. Over long legs it will bend slightly, but nothing sharp.
     
  3. lorax

    lorax Rising Contributor 10 Years

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    You'd have to heat the PVC pipe if you wanted to get any usable curve over that small a radius; a little handheld Bernzomatic torch works very well if you do want to try that; the very tip of a blue flame played just above the PVC seems to provide enough heat to make it flexible without burning it. However, since you're worrying about the curve compromising the growing area at the edges of the bed, it would be more logical to do as Steve (photopro) suggests and use the PVC knuckle-joints to make a squarer construction - this would get you equal vertical space in all areas of the beds.

    If you want an alternative material that will create an arch without resorting to heating, PET hose material, especially the black 1/4 or 1/2" diameter stuff used in commercial watering systems, is both flexible enough to make a graceful arch and stiff enough to hold that shape. I have no idea where you'd even look for it in Ontario; down here in Ecuador I go to a hose specialty store or an irrigation company, although in some towns it's also available at the local hardware stores. Try Home Depot or Rona/Revy/whatever they're calling it these days. It will be in the gardening section if they have it.

    Other than this, about a 10-gauge coated wire will work very well for what you're doing; if you can't find coated, you can always just use regular steel wire and spray it with enamel paint to keep it from corroding. The cheapest 10-ga coated wire I've ever found was old coathangers.
     
  4. pointy1

    pointy1 Member

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    Thanks Photopro and Lorax,
    I'll look in to the connectors and perhaps try heating as well. I found a site that suggests filling the pipe with sand first so the it doesn't buckle when you bend it. They managed to make a pretzel shape with 1/2 " pvc.
     
  5. lorax

    lorax Rising Contributor 10 Years

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    Yeah, I realized I should have said something about sand - if you heat empty pipe, it can collapse in on itself.
     
  6. vitog

    vitog Rising Contributor 10 Years

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    Pointy1, I found some discarded white PVC pipe, 3/4" diameter, that looked useful for my row covers; so I tried it out. It works fine on my 120 cm wide rows, although the natural shape is somewhat elliptical rather than circular. The narrower pipe that you mentioned should be even easier to bend than the stuff that I used, which can easily be bent to cover a 36" wide row. To get vertical sides, you might have to shape it on a frame, but I suspect that the 1/4" pipe will be very flexible. After a season in the garden, the pipe retains its curved shape quite well. I only use the PVC pipe for the end hoops. For intermediate hoops, where lateral stiffness is not required, I use portions of discarded vinyl siding - the thick nailing rib at the top, with all of the flat material below cut off. This makes effective hoops and it is free.
     
  7. pointy1

    pointy1 Member

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    Thanks Vitog, I'll keep my eyes open for used vinyl siding.
     
  8. M. D. Vaden

    M. D. Vaden Active Member 10 Years

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    From past experience, I found that PVC seems more brittle when cold.

    If you heated it, maybe try a blow dryer and shoot the hot air into the openings of several pieces at once. It would not melt them.

    I'd expect that you could bend a 5 foot long piece so that the ends were 2.5 feet apart, although maybe a longer piece if the ends need to go into the ground.

    The fitting idea suggested sounds practical, like a 90 or 45 degree fitting.

    When you buy the pipe, give a slight bend to Class 200 and also to the Schedule 40 with thicker walls, to see how it feels. My guess is that the 200 will bend better, but won't be as tough.
     
  9. mike anders

    mike anders Active Member

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    Hi All!

    If fittings are used it would be a good idea not to use solvent to fix them with. But the structure would need extra support against the wind. Then the framework can be dismantled when not required & stored neatly in the shed/garage etc. Or can be kept for another application.

    Poly pipe can be bent in a bending machine. That is 15mm & 22mm. But be sure to make the two bends exactly in the same plane. To do this, get a 4b pencil or felt marker, then scribe a continous line all along the side of the pipe through the portion which will have the two bends in it. See photos of my pipe benders. The pencil line, kept to the outside of the bend, will ensure that you get it right!
    1/2 " plastic pipe will fit into the 22mm part of the bending machine like in the photo.

    If a larger pipe is required you could ask a plumber to bend it for you with a hydrolic steel pipe bender. The type which is used to make galvd. hand rails. But it would require filling with sand and heating if plastic is used.

    Regards Mike Anders
     

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    Last edited: Mar 1, 2010

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