On 31 May, 11:33, "Peter" wrote:

As my angle grinder wont cut thro 4 inches should I cut twice ie make a sort
of inspection hole and hacksaw the back or is there an easier way.

Ring it from the outside, but without breaking all the way through,
then tap it with a cold chisel at which point the (brittle) cast iron
cracks neatly. This avoids running a high-speed grinder disk (or "fan"
as they're known) through the Inner Contents Layer...

Cast iron grinds, saws, cracks neatly. Even belting it with a sledge
can be quite a neat way to dismantle it (with practice) and it doesn't
split past the joints. If you are using a hammer, then slipping a
wooden wedge under the pipe to be smashed stops loading the joint into
the next one. You don't even need to make the grinder grooves connect
all the way, if you just think about where the stress risers are
pointing and where it wants to crack when thumped.