Dave Plowman (News) wrote:
In article ,
Stephen wrote:
Don't forget that compression fittings are BSP sized, therefore the
correct spanners will (or should be) imperial size.

I did wonder that when I measured 28.5mm but then I thought if the
pipe is metric, surely the fittings will be too; I was forgetting that
15 and 22 mm pipe are essentially 1/2 and 3/4 inch pipe.

15mm and 1/2" are quite close:

Half inch is near enough to 12.5 mm. 2 1/2 mm smaller than 15 mm

22mm and 3/4" ain't.

3/4 inch is near enough to 19 mm. 3 mm smaller.

Dave