tech22,
I am happy you haven't been injured, as the pressure related to your pump and lines can do serious AND dangerous bodily harm. Whoever repaired (spliced) your pressure line with copper just wasn't thinking straight. I would locate a complete new or used line and repair as soon as possible. Even sweated fittings and a 4000 psi hydraulic hose to replace the damage area would be better, but still temporary...flexible lines lack the exterior protection from the elements.
I agree with Norm, if a suitable replacement is difficult to locate, then seamless 18mm steel tubing should be used and brazed, silver soldered or compression fitted together for a permanent fix.
Good Luck, Mark