odd steel pipe sizes

[svouts]

Hi,
I am doing some work in an old house’s central heating and I have some odd steel pipe sizes. I can measure the bellow outer diameter of the pipes:

2.2 cm

2.7 cm

3.5 cm

4.2 cm

4.9 cm

6.3 cm

7.7 cm

Any idea what sizes in inches are above?

Many thanks

 

[oldbuffer]

Steel pipe is sized by the internal bore. You could convert your figures to inches and check on the internet for the likely internal diameter of these exterior diameters.

 

[Hugh Jaleak]

https://www.pipefittingsdirect.co.uk/contents/en-uk/d15.html