It’s important to get the correct flange. Measure your flange using the guide below and review the measurements using the Flange Identification Chart to see which flange is appropriate for your use. One of the most important measurements is the Pitch Circle Diameter (PCD) which can determine if the flange bolt holes will match each other.
A: Inside Diameter
Measure across the centre from one side of the internal hole to the opposite side of the hole. This will tell you what size tube or pipe is needed.
B: Outside Diameter
Measure across the centre from the external edge to the other external edge of the flange.
C: Pitch Circle Diameter (PCD)
Measure from centre of the bolt hole to centre of the opposite bolt hole. This can also be measured from the external edge of the bolt hole to the internal edge of the opposite bolt hole. This measurement will tell you the distance between the bolt holes so that you can match the same flanges together.
D: Hole Size
Measure from edge to edge, across the centre of a bolt hole. This will generally be slightly larger than the metric bolt being used.
Measure from one edge of the ﬂat face to the other.