USED FOR:
(Parts 1–3) Metallic flanges
Dimensional and pressure-rating standardization of flanges — steel (Part 1), cast iron (Part 2), copper alloy and composite (Part 3).
RELATED STANDARDS:
- ASME B16.47 “Large Diameter Steel Flanges – NPS 26 Through NPS 60”
- EN 1092-1 “Flanges and their joints – Circular flanges for pipes, valves, fittings and accessories, PN designated – Part 1: Steel flanges”
- MSS SP-44 – Steel Pipeline Flanges
- ASME B16.20 / EN 1514-1 “Metallic and non-metallic gaskets for pipe flanges”
DIMENSIONAL RANGE:
Part 1 covers steel flanges typically from DN 10 up to very large diameters, commonly cited as DN 4000 in commercial catalogues, across the full family of PN ratings from PN 6 up through PN 400/PN 420, mirroring the ASME B16.5 (Class 150 to 2500) and B16.47 pressure classes on the metric side. Part 2, for cast iron, runs over a narrower nominal-size band, broadly DN 10 to DN 2000, with pressure ratings from PN 6 up to around PN 160. Part 3, for copper alloy and composite flanges, sits at the lower end of both size and pressure, generally PN 10 to PN 50. We always treat the upper-end figures as indicative rather than contractual, since the authoritative table sits in the paid ISO text and different national adoptions (EN 1092, AS 4331) don’t extend identically at every PN.
DESCRIPTION:
The ISO counterpart to ASME B16.5/B16.47. In practice, on internationally mixed projects we have had to reconcile ISO 7005 (often aligned with EN 1092) against ASME flange tables, because bolt circles, hole counts, and facing details are not automatically interchangeable even at “equivalent” pressure classes.
IMPORTANT NOTES:
Never assume an ISO/EN flange will bolt straight up to an ASME flange of the “same” rating without checking the actual dimensional tables, this is a recurring source of field fit-up problems, especially at interfaces between packages sourced from different regions.
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