Our heat exchanger
on the main engine (common marine engine Cummins 5.9l) is copper and a few elbows associated with it are copper with a (very shallow) flare like the one in the middle pic of post #19. We have used a bit of bronze pipe and fittings in a few other places associated with this raw water cooling circuit but since there were a couple aged hoses on the coolant
side we needed to replace and the Cummins rep in the port wasn't too helpful, we just went to the local autoparts place and started sorting through, with a helpful clerk, the radiator hoses until we found some with the size and bend needed for our situation. We cut off the excess bits of hose we didn't need and actually have been pretty pleased with the use of these car part radiator hoses.
The bronze or copper both benefit from a coat of nice paint
before they are installed on the boat. You'll be able to see leaks
if you paint
them. We paint all engine parts
before install (like the exterior bronze case of the raw water pump) as it helps us identify problems/leaks.