I’ve converted to +2 calipers so have removed the servo. I therefore need a short length of copper pipe from the master cylinder to the T piece from where the front and rear brakes connect.
I’m reusing a length of the copper pipe which originally went to the servo and is in good condition and I have cut to a suitable length. I have one end that needs flaring to connect to the T piece. The other original end has a double flare which I think was either connected to the master cylinder or servo. I took the pipe along to my friendly local garage and was offered a single or double flare.
Richard, copper brake pipe can work harden and crack. Its banned for this reason in Germany. CuNi (easy to get from AutoMec and many others) is much more resistant.
To select the correct flare for the joint you are making, a convex male part must mate to a female (double) flare, a concave female part must mate to a male (bubble) flare. For example, the bore in the 16PB calipers is concave female, so needs a matching male bubble flare on the end of the pipe that matches.