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API FLANGE SLIDE RULE

Flange & Ring Gasket Reference · NFC Services
Flange Size (Nominal)
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Pressure Rating

Select a flange size and pressure class,
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BX ring gaskets are pressure-energized and used with Type 6BX flanges (10M, 15M, 20M). R and RX rings are used with Type 6B flanges (2M, 3M, 5M). RX gaskets provide a pressure-energized seal; R gaskets do not.
Groove pitch diameters are sourced from metric API 6A tables and converted to inches; minor rounding differences from fractional equivalents may occur.
Stud bolt and tap end stud lengths assume RX-gasket service on Type 6B flanges (API 6A Annex I, Tables I.1/I.3, matching the PE ring numbers shown) and BX service on Type 6BX flanges. Plain R-gasket service uses Tables I.5/I.6 — bolt lengths may differ. Verify before ordering for R-gasket assemblies.