Originally Posted by Chas Erwin
Before you commit please consult your metallurgical properties references
and ask yourself why no manufacturer uses copper for oil line (nor vehicle brake line either for that matter.)
While I agree there are some risks with copper. I'm using 3/16" soft copper tubing with a working pressure of 1900 PSI. Yes I will have strain relief and I'm thinking a loop in the tubing for thermal expansion. Just for fun.
Plus I'm soldering the fitting, not brazing. Brazing anneals the copper and makes the joint a failure point. Soldering at 500 degrees does not anneal the copper and preserves the malleability/strength of the copper tube at the joint.
Saw the results of that, gee 20 years ago at the Luxor casino, where the mechanical contractor had brazed the 3/4" copper fittings on the heating
loop for the rooms. Faster that way you know... Then they ran the boilers without good or any real temp control and water
temp rose to 220-230 degrees (pressure water). They were running the boilers to keep the building warm in winter so the painters could finish up the rooms. Interesting building.
The copper piping expanded floor to floor, which because of the pyramid shape (the piping was running along the exterior slope), was about 15'-16'. The annealed joints failed at oh 1200 places right at the brazed joint. Spec was for solder joints I believe. Exciting!. A great lesson on the issues with annealing copper at brazing temperatures. A combination of "Issues" caused a rather large set of leaks
. In finished rooms... with carpet.
Yes copper will work harden over time, if it is subjected to excessive strain/vibration. But the connections are all on the engine and not going off engine. So vibration, torsional strain is less an issue. If I was going from engine to another location, there would be a greater issue with work hardening. I am putting a loop in the piping which will relieve stain at the fittings.
Copper use to be used for fuel
and oil lines all the time till the 1940's and shortage of copper due to the war effort. Copper IS less forgiving and can become brittle. I'm thinking / hoping I'm aware enough to adjust the design to make it work reasonably well.