Copper tube bend failure

[irishal]

Hello,

Need some help finding the cause of a failure of a copper tube bend on a small HVAC split unit. The 6mm copper pipe carries R422 refrigerant and has failed at least 3 times now on the inside of the bend. The bend was made using a pipe bender. The failure appears to be a pin hole failure. Fairly minor I know but it keeps giving my maintenance team a head ache getting it fixed. Our local HVAC contractor keeps going for a like for like replacement and is not offering any solutions.

Cheers,
Al

 

[imok2]

You need to be using soft copper, try applying a little heat as you make the bend and use as large a radious as you can to lesson the stress on the inside bend.

 

[IRstuff]

Or, use an oxygen-free copper. Normal copper work-hardens

TTFN

 

[Yorkman]

I'm with imok2 hard drawn ACR tubing can't stand up to the stresses of bending without annealing, trust me been there, screwed that up!!. If your going to use ACR hard drawn; heat the tubing until the tube shows a bit of blueing this should be done with an N2 purge running. The alternative would be to use annealed ACR from the box, unfortunetly this comes in rather large coil lengths (50/100Ft) P.S.Can you patch the pin-hole with some 15%BCuP braizing alloy to get you through?

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[WhoDey09]

may want to look into replacing. how much time have you paid for, for your service guy to patch it 3 times?

 

[revisw]

You should not attempt to bend hard copper tubing. Instead use appropriate fittings to form required directions.