Custom o-ring 2m (78inch) flange flattness

[DavidCR]

Hello and blessings to all.

I need to specify the flange face flatness manufacturing tolerances for a flange with rubber o-ring seal.

The flange is for a 2m diameter pipe custom design for cold water.

I have the o-ring groove design and required finishes, but noy sure how to specify the tolerance for manufacturng the flange faces to ensure the geometric contact of the faces is flat and parallel.

Thanks a lot for any recommendation.

 

[Doug Hunter]

Your O-ring design guidance should also give a finish and flatness for the mating flange face. If not, try Parker.com. At the very least, you can apply the flange tolerances to the entire flange face (not just the portion capping the groove). If that is not manufacturing feasible, then you can try taking the manufacturing capability limits back to the O-ring supplier for their evaluation. If that doesn't resolve your issues, you can do a calculation to see how much the flatnesses of the 2 flange faces add to the effective O-ring groove depth, which is ultimately what controls your O-ring compression to the proper range. You can reduce your O-ring depth tolerance by the amount that the flatnesses add, or choose to live with a wider compression range.