3" and 4" prefabricated flanges

[Chris Mc]

A question for the pipe fitters out there or anyone else in the know.

In prefabricated mild steel flanges at what size diameter does the flange change from a 4 hole one to an 8 hole one, I am of the belief it's between 3" and 4" 

Just want clarity on it 

Thanks

[JohnMo]

It depends on pipe schedule (how thick it is) as pipe size is stated in nominal dimensions. Take a look below.

 

https://www.valvesonline.co.uk/free-flange-tables?srsltid=AfmBOoqG7T3lPn0niO-55d0uNIKyHb0fiw_B9U79sEyC9H4moDn7wnUL