In message , Andrew
writes
Has anyone done this ?.

I have a 22mm bending spring intended for 22mm copper
and it is a fairly loose fit.

I was going to heat the pipe with my hot air gun
and bend it around something round or maybe
hammer some nails into a bit of old plywood and
use them as a 90 degree guide.

I am replacing the gas pipe that was used to run
power from house to garage in 1976 with the correct
stuff, so needs a 90 degree bend at each end to fit
a metre wide path, before re-instating the path
(dug up for other reasons).

Yes. I only heated the inside of the bend in stages. Applying force
causes a kink to form. Allow that to cool before starting the next. Not
hugely pretty.
Electric paint stripper with slotted nozzle.

--
Tim Lamb