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Bending copper pipe

Bending copper pipe

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Chris Gunn20/09/2016 19:46:44
459 forum posts
28 photos

Mark, just heat it up to red heat and let it cool naturally, do not hold it under the tap, then it will be soft. Be careful you do not crush it though. It will work harden if you keep working it, and you just reheat it and let it cool again and away you go.

Chris Gunn

martin perman20/09/2016 20:18:53
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2095 forum posts
75 photos

I also find a nice long soak in the oven, when wife out for day, works well followed by slow cooling.

Martin P

not done it yet20/09/2016 23:40:35
7517 forum posts
20 photos

Apparently copper is one of those metals which remain soft after heating however it is cooled. Only work hardens. I have always cooled slowly, thinking it needed to be done that way, so as it works and it cools fairly quickly anyway, I have no burning desire to change. But nice to know it does not really matter.

Roderick Jenkins21/09/2016 00:01:16
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2376 forum posts
800 photos

Yes, no need to cool copper slowly. I like to quench from hot into cold water because A) I'm impatient and B) it shocks some of the scale off and makes the pickle last longer.

However, Mark's original question says he has cones on the end of the pipe so if these are soft soldered and he wishes to keep them intact he is probably out of luck since the annealing temperature (about 400C minimum) needs to be well over the melting point of soft solder. Probably OK for silver soldered joints though it may be wise to put some flux on them before heating.

Rod

Hopper21/09/2016 05:28:41
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7881 forum posts
397 photos

If you want to keep the soldered cones in place you will need a heat sink between the section being annealed and the soldered part. Dependiing on size etc, a pair of vice grips are often sufficient. For more heavy duty applications, a large potato forced over the tube will absorb an amazing amount of heat before it can get to the soldered section. (We used to use a sort of papier mache ball made from asbestos shreds and water but they won't let you do that any more) Trick is to heat the annealing section up quickly to dull red then plunge it in a bucket of water, thus minimizing the time available for heat to travel past the heat sink. If you know where your bends are going to be, you can anneal each of those specific areas one at a time to stop heat build up in the the pipe overall.

Tim Stevens21/09/2016 10:06:02
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1779 forum posts
1 photos

If you have really tight curves to make, you will find it helpful to fill the pipe with something so that the bends do not collapse around the outside. Soft solder or lead can be used, and I have read that there is a plastic which works too. It has a low melting point and comes in pellet form but I cannot recall the name. Anyone?

And of course use a grooved former for the inside of the bend, too. This can be turned in hardwood to the size required, if you can find nothing off-the-shelf.

Cheers, Tim

Brian H21/09/2016 10:11:21
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2312 forum posts
112 photos

I am fortunate in having a supply of Cerobend which is a strange alloy that melts in hot water, very useful for pipe bending but needs to be completly removed if silver soldering.

mechman4821/09/2016 10:32:52
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2947 forum posts
468 photos

It has been known to use sand packed into the tube, you can also get pipe bending springs of various diameters.

George.

Brian Wood21/09/2016 16:33:50
2742 forum posts
39 photos

Whether or not Mark could get a spring into the pipe now that fittings are on each end depends on the internal diameters of the fittings and any hard solder residues.

​The trick with pipe springs, as any plumber will tell you, is to over -bend as the first move, then ease the bend back to release the spring. The pipe tends to collapse onto the spring and there is no way the spring can be pulled out without damage to it if you don't ease the bend in this way

My early days of plumbing taught me that lesson, the expensive way. His other alternative is to use Cerrobend and melt it out with hot water afterwards. That resists flattening and creasing on the outer and inner sides of the bend, another hazard, especially creasing, that will trap a spring. Careful work with a sheet metal hammer around the sides of the bend is the only way of releasing one caught that way

Regards
​Brian

john fletcher 121/09/2016 18:02:43
893 forum posts

If you have over bent a piece of copper tube using a spring, useually if you wind up the spring in the correct direction the spring will come out, but it does take a lot of effort. In former times the heating and ventilation people who used 3 or maybe 5 inch steel heating pipe would fill the pipe with very dry sand with a cap either end and using Oxy/acetylene bottles to heat the pipe would make expansion loops on long runs. Now days they will have a hydraulic bender with a digital readout and key board. I think kiln dry sand as used by block pavers would be OK but make sure it is definitely dry. When I have used sand I always put it in the oven before use to drive out any moisture, ensuring I didn't generate steam and maybe blow the sealing caps off, ruining the job. Primitive but it works.John

david williams 1422/09/2016 16:32:02
16 forum posts

suprising how quickly some copper pipe work hardens. if you feel it go stiff, stop and reheat, really frustrating when a second bend breaks

Dave Halford23/09/2016 19:46:04
2536 forum posts
24 photos
Posted by Brian Hutchings on 21/09/2016 10:11:21:

I am fortunate in having a supply of Cerobend which is a strange alloy that melts in hot water, very useful for pipe bending but needs to be completly removed if silver soldering.

A better use for that would be to cast some teaspoons out of it.

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