Flanges are indispensable in pipelines, so how to check whether the flanges you buy are standard? We need to measure the inner diameter, outer diameter, thickness, number of holes and hole size of the flanges.

Essential Measuring Tools

Ruler or Vernier Caliper – for measuring thickness and size.

A pen – to record the measurement results

Flange Standard Table – to find out if the flange you are measuring meets the standard.

Measurement steps

OD – Outer Diameter

Use a tape measure or ruler to measure the diameter of the flange from the outermost edge to the other edge.

If the flange is connected to a hose, use a diameter tape measure and record the measurement after wrapping around the outside of the flange.

ID – Inner Diameter

Measure the diameter of the opening of the inner hole of the flange and record the result with a tape measure or ruler.

This dimension determines the outer diameter of the pipe or tube that the flange fits.

PCD – Pitch Circle Diameter

The pitch circle diameter is the distance from the center of the bolt hole to the center of the bolt hole on the opposite side.

It can be measured in two ways:

Measure directly from the center of the bolt hole to the center of the opposite bolt hole.

Measure the outer edge of one bolt hole to the inner edge of the opposite bolt hole and add the diameter of the bolt hole.

Bolt hole size measurement

Use a caliper or ruler to measure the diameter of each bolt hole (edge ​​to edge width).

The bolt hole size is usually slightly larger than the actual bolt size used to ensure installation flexibility.

Calculation of bolt hole quantity

Count the number of bolt holes on the flange and record them.

Ensure that they are consistent with the required standards or actual usage requirements.

Flange thickness measurement (Thickness)

Use a tape measure, ruler or vernier caliper to measure the thickness from the flat surface of one side of the flange to the other side.

Flange thickness can reflect its strength grade and is also an important reference for judging flange drilling specifications.

Measurement Considerations

In addition to the above routine inspections, flange measurement also requires inspection of the material and whether it is coated with anti-rust paint if necessary. High-precision tools are used for measurement to avoid errors.

Conclusion

Flange measurement is a routine test before the flange is used. This ensures that the flange can be installed correctly. If you have other tests such as material and pressure level, you can ask a third party to test it.