Bending Pipe

[coldjoker]

Hey guys I am new to this site, I have a question about Heating Hard Drone copper tube? I have done a few Wal-Mart installs and a few other where we have heated ACR to make doglegs and such around objects to cut down on 90's and pressure drops. The company I am with now claims that on Hot/kool gas defrost that heating the copper will weaken it and make it burst at the bend. I have done 100's of heated bends and had no troubles, the bends were from 20 - 40 degress not like full 90s or more what is your guys opion. Thanks Cold Joker

[SteinarN]

Hey guys I am new to this site, I have a question about Heating Hard Drone copper tube? I have done a few Wal-Mart installs and a few other where we have heated ACR to make doglegs and such around objects to cut down on 90's and pressure drops. The company I am with now claims that on Hot/kool gas defrost that heating the copper will weaken it and make it burst at the bend. I have done 100's of heated bends and had no troubles, the bends were from 20 - 40 degress not like full 90s or more what is your guys opion. Thanks Cold Joker

Hmmm, if you werent to heat and bend the tube, how does your company sugests you should go around corners? Soft-soldering fittings? Normal phosphor solder also make the tube soft.

I've seen some tables of the burst pressure. 1/4" tube has a burst pressure of several 1.000 psi. Larger tubes have far less burst pressure. But i've never heard of the possibility of bursting tubes due to heating them.

I have an electric bending tool. It bends hard drone copper tubes up to 1-3/8" with perfect results. :) The best tool i ever have bought. It looks impressive in the plant room when you look at a 5m long 1-3/8" suction tube with several smoth 90degres turn made with that tool.

[dsp]

I have used those electric bending tools they are awesome. Really worthwhile considering the time and cost of brazing bends.
dsp

[nike123]

Hi SteinarN!

Could you post make and model of your bending tool?

Thanks.

[Tesla]

It depends on quality (thickness/purity) of tube and the amount of stress when bent. Need to be heating tube to "cherry red" or oxidation colour black/brown to anneal it, let it cool a bit, then form a bend. I have also done hundreds with no probs. But what the company has said is correct as hard drawn Cu tube is stronger than soft drawn. When we anneal the tube to form it, we don't have uniform hardness throughout tube therby weakening it.

[old gas bottle]

i,am thinking that a bend on a pipe is stronger than a brazed elbow, warming it to bend it has to be better and i also would not get it to the point of oxydising either for obvious reasons, when a elbow is brazed in the joint is stronger than the pipe just above the joint which will have thined with the intense heat , plus there is no joint to leak. no contest realy and nice to see,;)

[SteinarN]

Hi SteinarN!

Could you post make and model of your bending tool?

Thanks.


http://www.rems.de/go.aspx?lid=2&tid=15&pgid=5

http://www.rems.de/maint_files/deu/files/BA%20Curvo%20Curvo50%20Sinus%20-%20Stand%2011-2007_0.pdf

I have the smal Rems Curvo. It bends up to 1-3/8" and up to 180 degres. There is other makes also, but i think Rems is the best make. I had to order bending formers for inch tubes specially. The suplier had them only with metric bending formers as standard.

[Thermatech]

When R410a a/c units were first introduced in the uk a company did some independant pressure tests to see what the real burst pressure of copper tube would be.
A number of typical sections of 3/4 to 1 1/8 tube were made up with flare connections, expanded straight brazed connections, brazed straight couplers & 90 deg bends.
These sections of tube were sent to a university for the pressure testing.
Almost without exception the burst location on half hard straight tube was where the tube had been heated & cooled. So on a 90 deg bend fitting which had been brazed the actual fitting & joint survived in tact but the tube burst an inch or two back from the joint. At this location the tube had only been exposed to the heat from brazing the joint & then allowed to cool.
The same with an expanded straight brazed joint. You might expect the weakest point to be where the tube has been expanded but still the burst location was an inch or two back from the brazed joint.

The burst pressures for these tests was at least 2 & up to 4 times higher than the max working pressure of R410a.

However in the case of heating the tube to make it softer & then bending it the tube will also be stretched on the outside of the bend & will be slightly thinner wall thichness on the outside of the bend. At this location the tube will be weak due to being soft because of heating & cooling & also thinner wall thickness because of bending.

[coldjoker]

Thanks guys that was a quick reply

[Alex Harvey]

The bending tools are becoming increasingly popular and good practice is the fewer joints the better as each joint has a chance of failure and each additional joint increases the chance of failure even if only theory.

As advised already REMS made a bender call the curvo, I found this site which has film of a REMS curvo on the section bending www.rackettering-rems-tools-press-distribitor.co.uk

Rothenberger also a German manufactuer offer pipe benders including the Robend 3000 electic pipe bender which can be viewed on this site www.rothenberger-tool-uk-sales-and-hire.co.uk but no film only pictures and discriptions.

But joints can not the avoided all together in larger bore or hard copper and a good joint should not fail but there is in theory no 100% perfect joint. The copper can become work hardened if there is vibration on the pipe which can cause facture at joints or bends.

[coolhibby1875]

you should be able to bend pipe up to 1 5/8 with the right benders without heat, After that you should use copper fittings for strenght and after 1 3/8 these should be long radius bends and not short.

[benny17]

do what ever you like just make sure you have the standard and code on your pipe run ie we have australian standards 1571 which meets the requirements for r410 heat as much as you like no differnce then soldering it