AS 4087 - Metallic Flanges for Waterworks Purposes

Formerly included in AS2129, this standard covers nominal sizes of DN 15 (NPS 1/2") to DN 1200 (NPS 48") in various materials and pressure ratings designated by their allowable operating pressure (AOP) - PN Rating - but the nominal size range is limited to DN 50 (NPS 2") to DN 1200 (NPS 48") with pressure ratings of PN 16, PN 21 and PN 35 for stainless steel grades of material.
These flanges are generally stocked in sizes DN50 (NPS 2") to DN 600 (NPS 24") with a P 16 pressure rating.  The other sizes and pressure ratings are available with a lead time.

AS 4087 Dimensions