Bending pipe

[glenn1340]

Here`s a question:
Is it ok to bend hard copper tube (after annealing and purging with nitrogen)? I ask this as a guy on a course said by bending the tube the outer diameter could become stretched and weakened. We know, however, that it`s often not possible to fit a elbow or bend. Also time is a major consideration as is the equation: more joints = possibility of more leaks.

Any thoughts on this?

Glenn

Oh, maybe if I just bent the tube over my knee...

[monkey spanners]

I think the three and six meter lenghts are called half hard copper. I have been bending these in sizes up to 1 1/8" with out any failures, but i can't tell you if this does or does not match any good practice thingies that may exist.
I had this discussion recently on a R410A install and one of my collegues pointed out that the outdoor VRF units are full of bent bits of pipe and that fittings were conspicious by their absence....
Like you say there are less joints and a manufacturered bend must flow better also.
Hopfully some more knowledgeable members will be able to answer your question.

Jon

[frank]

I wouldn't worry about it.

I've just had to replace 2 whole condensers on Daikin RZQ outdoor units as they started to leak on the condenser bends. You know, the little 180 degree bends that connect the coil pipes together.
So thin that you could press your finger into them :eek: (if you are Strong like me - he he)

Apparently, the crimping tool used in the factory must have been set too high a pressure and they start to leak after a couple of years. Not any sort of argument from the supplier when you report it - just a new part despatched.

If they can fit such thin materials on the condenser which carries R410A pressures, why do we need to fit increased thickness pipework on site??

[nike123]

Make some bends and test it with hydraulic (water) pump to find what is burst pressure and you will know is it good or not.

[glenn1340]

Make some bends and test it with hydraulic (water) pump to find what is burst pressure and you will know is it good or not.

Good Idea, next time I`m in the yard I`ll get the test bucket out. I`ll let you know the results.
Now where`s that wet suit?

[old gas bottle]

just get bending, the less elbows the better and dont worry about the pipe splitting , the brazed joints are more at risk from high pressure failure just above the joint where the extreem heat weakens it,also the joint can leak if your having a bad day, cant beat seeing a nice install where the engineer knows how to use a set of benders.;)

[top engineer]

i have been building refrigeration packs for years and have been bending pipe upto 15/8 never had any problems as with most pipework it gets pressure tested so if it is done correctly should be no worries

[glenn1340]

Thanks for all the replys guys. I`m with you lot, probably in theory the pipe could weaken but there again in theory we could all be hit by that asteroid that`s out there winging it`s way to us. So I`ll carry on with that bender.

[paul_h]

I remember my old bosses comment a couple of years ago, (he was in the trade since the 60s). He sent me to a unit that needed a remote condenser fitted (sight unseen so none of us knew what the job required).
I called back saying I need X pipe sizes and x amount of elbows, x amount on strut and brackets etc.
He said "what the hell you want elbows for? It's only going to put crap in the system, make the job take longer, have a bigger chance of leaks and look ugly"

I guess the only elbowed and brazed systems that look good are the fully insulated or painted ones ;)
I only work with things that are under 3/4" though so YMMV.

[sokold]

if we weren't meant to use pipe benders then they wouldn't sell them.......i never use elbows if i can help it...

so who masures to the back of the bend and who goes for the centre ? i'm a back bend boy myself

[glenn1340]

so who masures to the back of the bend and who goes for the centre ? i'm a back bend boy myself

I`ll go for the centre of the pipe.
By the way, what`s the opinion on those multi pipe benders where you need three hands? I gave up with them and invested in decent single size ones. So easy to use and less chance of nipping your fingers trying to hold the former in place.

[littleyapper]

i agree ...bending pipe was part of every bodies training inc mine .....BUT the"P.E.D" AND "en 378" have reference to bending pipe.... not as clear cut as we might like to think.... fittings are now the preferred option and all fittings should meet a particular standard .... after bending a pipe the wall thickness should be above the required thickness depending on pipe dia. sorry to "bend" your thinking on this but the regs are very much in force....

[jdunc2301]

Fittings mean more chance of leakage, looks unsightly and takes time....and i haven't used them in 5 years i am mainly service though!

Well made bends are very neat looking and reduce chance of leakage annd costs less.....

I wouldn't worry about pipe diameter.. is it just me or is it all getting a little over the top?

[sokold]

part of the F-Gas regulations.....use copper coils instead of straight lengths if possible - to cut down on joints.

to me, that's a license to bend :D

[subb-zero]

That's right more joints more possible leaks. But if you have to then do it.

[surfacehilly]

hi newbie here but been in the heatexchanger world to long, most manufactures bent the pipes for speed, price and its automated, if your worried dry some fine sand plug the tubes pout in the sand and use bending tool will keep the pipe in shape inside and out also will stop flat spots let it cool down on its own to

bill

[sokold]

hmmmm, i wouldn't go pouring sand down your pipework :eek:....but if you think it's a good idea, let us know how this affects system performance !