On Thu, 25 Jun 2015 09:51:29 -0700, wrote:

On Wed, 24 Jun 2015 13:15:47 -0500, "Paul K. Dickman"
wrote:

Except for certain alloys it doesn't age harden.
But refer tube has a pretty wide tolerance in wall thickness. Typically
+-10% of the thickness.
My guess is that when copper was cheaper, they erred on the plus side, now
they lean to the minus.

One could as much as 20% thicker than the other.

Paul K. Dickman

wrote in message
. ..
Copper tubing to be exact. I have a couple rolled lengths of soft
copper tube. One length is about 20 years old and the other about 4
years old. Both are the soft copper tubing commonly used for
refrigeration or water. It comes with a plastic cap on each end.
Anyway, my old rolled length, which I discovered the other day when
cleaning out some junk, is much stiffer than the new roll. So I am
wondering if the copper got stiffer over time because the older stuff
is quite a bit harder to bend than the newer stuff.
Eric

Greetings Paul,
I can check that. I just checked, both coils have the same wall
thickness and O.D. I think it must just be different types of copper
tube.
Eric

More likely it's different degrees of annealing. Copper readily work
hardens, and the soft type has to be thoroughly annealed so it will
freely bend.

Heat treating isn't always consistent.

--
Ed Huntress