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Bending plastic piping


NavisBD

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I have to do a considerable amount of rerouting the pipework on my 'project', because the previous owner had left all the pipework visible and also taking some crazy routes. I don't wish to visit the merits of plastic v copper pipe; at the moment I have an open mind.

 

However, I am interested to hear people's views on bending plastic pipes. Youtube is full of demonstrations of how, using for example heated sand, plastic piping can be gently curved to a rigid and unkinked 45/90 degree angle. But orthodox plumbing guides always seem to recommend using coupling joints, despite the fact that these are quite bulky and visibly ruin the line. I can only assume that there are good physical reasons for always going with couplings rather than bending, but I don't know what they are.

 

Have any members successfully bent plastic pipe instead of using a coupling?

Edited by NavisBD
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You can permanently bend it by softening the area carefully with a heat gun - keep the gun moving and don't overheat the pipe.

 

Not sure I'd want to though.

 

Tony

Tony,

 

This is the heart of the matter for me though - I am confident it can be done, so I am interested in why nobody seems to do it. Why are you not sure you'd want to?

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Had to fit some of that reinforced clear plastic tubing over a hose barb the other day. Heating it with a hardryer helped a little but dunking it in near boiling water totally softened it allowing fitting with one push.

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Tony,

 

This is the heart of the matter for me though - I am confident it can be done, so I am interested in why nobody seems to do it. Why are you not sure you'd want to?

Two reasons:

 

The application of heat has to be very carefully done - a hair dryer won't do it but a heat gun will - because if it's overdone the pipe will wrinkle or crease. If I'd made a dozen connections/bends and then screwed up the last one I'd use an unpleasant word.

 

Also, 45 degree bends, slow bends, 90 degree bends etc are easily available and guaranteed to work first time so why bother?

 

However, as noted above, you can cold bend it and hold it in place with clips if required.

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Two reasons:

 

The application of heat has to be very carefully done - a hair dryer won't do it but a heat gun will - because if it's overdone the pipe will wrinkle or crease. If I'd made a dozen connections/bends and then screwed up the last one I'd use an unpleasant word.

 

Also, 45 degree bends, slow bends, 90 degree bends etc are easily available and guaranteed to work first time so why bother?

 

However, as noted above, you can cold bend it and hold it in place with clips if required.

Thanks Tony,

 

Yes, 90 degree bends are available but they are quite bulky. Working in a confined space, I want to get both hot and cold pipes to run as closely together as possible - once you introduce couplers the distance between the pipes gets quite large, as well as looking awful. This is an example what I'm working with, and illustrates what I mean about corner couplings ruining the line.

 

Piping%20original%20close%20up%20for%20F

Edited by NavisBD
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Thanks Tony,

 

Yes, 90 degree bends are available but they are quite bulky. Working in a confined space, I want to get both hot and cold pipes to run as closely together as possible - once you introduce couplers the distance between the pipes gets quite large, as well as looking awful. This is an example what I'm working with, and illustrates what I mean about corner couplings ruining the line.

 

 

 

Good idea but not too close as you will get warm,cold water. icecream.gif

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One reason to use plastic fittings rather than trying to bend it is if the bend subsequently fails (for whatever reason), you'll be in trouble and have to replace the whole length of pipe, whereas if you've used an elbow instead, you can easily replace it.

 

I'd talk directly to the pipe manufacturers for their advice about how to bend it, or indeed if you can bend it.

 

Personally I wouldn't worry about the appearance of the plastic pipework though, as whatever you do, unless you can box it in, it will always look awful.

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You can bend speedfit & the limits of bend are on the JohnGuest website. The cold-formed bends work but can be awkward as they have a bit of a flange which is always in the place that you don't want. I avoid joints wherever possible and use the coiled up stuff. Keep this in the bag it comes in to protect it from scratching until you use it. I used to be great fan of soldered copper (Yorkshire) then compression and now plastic pushfit. The only drawback for me is the lack of certain specialised fittings which you have to buy in brass /bronze. Has this got anything to do with the thread topic? I have forgotten.

I'm guessing you can only glue ABS (&similar?) waste fittings.

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You can bend John Guest barrier pipe with a bending spring as normal.

 

 

Really? What spring are you using given the internal diameter of JG Speedfit tube is about 2mm smaller than a 'normal' bending spring? And I can't imagine the bend staying 'in' when you pull the spring out, let alone when you run hot water through the pipe.

 

 

 

They sell cold forming brackets to maintain the shape but if you warm the pipe with a heat gun (or even boiling water) the bend will hold.

 

 

This is not a method approved by the manufacturer AFAIK.

Tony,

 

This is the heart of the matter for me though - I am confident it can be done, so I am interested in why nobody seems to do it. Why are you not sure you'd want to?

 

 

Because if a pipe failure occurs as a result, the manufacturer will be falling over themselves to blame you for abuse of their product.

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Really? What spring are you using given the internal diameter of JG Speedfit tube is about 2mm smaller than a 'normal' bending spring? And I can't imagine the bend staying 'in' when you pull the spring out, let alone when you run hot water through the pipe.

 

Yes really. You obviously don't bend barrier pipe very often. Never said a normal bending spring will do the job. I just mentioned JG can be cold formed using a bending spring as normal.

Rather than trying to be clever mike you perhaps should have pointed out that normal size bending spring won't fit a JG pipe so the OP will need to buy a JG spring

 

 

This is not a method approved by the manufacturer AFAIK.

Lots of things are not approved by manufacturers, but that doesn't mean that its not possible.

 

Because if a pipe failure occurs as a result, the manufacturer will be falling over themselves to blame you for abuse of their product.

Something tells me the above is highly unlikely to happen as long as you don't overdo it.

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You can also use a bending machine.

Yes, that's what that link stated.

"It is also possible to bend Speedfit Pipe using a standard pipe bender. The pipe should not be heated with a blowlamp or hot air gun."

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