Navigating Flange Standards
Australia's industrial infrastructure uses a mix of local, American, and European pipe flange standards, often within the same facility. Selecting the correct flange gasket size requires identifying which standard and pressure class your flange belongs to. We manufacture to all of them.
Can't see your standard below? Our Gasket Generator looks up seven flange standards (including AS 4087, BS, and JIS) and matches approximate measurements to the nearest catalogued size.
Search the CatalogueDN vs NPS: Nominal Size Designations
DN (nominal diameter) is the metric designation used by AS 2129 and EN 1514. NPS (Nominal Pipe Size) is the imperial designation used by ASME. Both are nominal — they don't represent the actual measured pipe diameter. For example, DN 50 and NPS 2" both refer to the same pipe size (60.3 mm OD).
All dimensions in the tables below are in millimetres (mm). ASME tables show both NPS and the DN equivalent for convenience.
Full Face vs Ring Gaskets
Every dimension table below includes both the Ring OD and the Full Face OD. The correct choice depends on your flange face type.
Full Face Gaskets
For Flat Face (FF) flanges
Extended to the outside diameter of the flange, with bolt holes punched through the gasket. These are essential for Flat Face flanges to prevent bending of brittle flange materials (such as cast iron) during bolt tightening.
Use the Full Face OD, PCD, Bolts, and Bolt Hole columns.
Ring Gaskets
For Raised Face (RF) flanges
Ring gaskets (also called IBC, Inner Bolt Circle) sit inside the ring of bolts, on the raised face. These are used on Raised Face flanges to concentrate bolt load onto a smaller sealing area, improving gasket compression and seal performance.
Use the Ring OD column. Bolt hole dimensions are not needed for ring gaskets.
AS 2129 — Australian Standard
AS 2129 is the long-standing general-purpose flange standard across Australian industry, mining, and legacy infrastructure. Table D covers lower pressures; Table E and Table H cover higher. All share the same nominal bore range. For modern water-industry flanges, see AS 4087 below.
Select a table to switch. All dimensions in mm.
Source: AS 2129-2000 — Flanges for pipes, valves and fittings. Verify against your physical flange.
AS 4087 — Australian Water-Industry Flanges
AS 4087 is the modern standard for water-industry flanges: pump stations, treatment plants, and water mains. It is PN-rated, where AS 2129 is Table-rated, and its flanges come flat-face or raised-face. Flat face is common on cast- and ductile-iron valves and fittings, which take a full-face gasket. At common sizes the PN 16 drilling matches AS 2129 Table D, so confirm which standard your flange is built to before ordering. PN 21 is the higher-pressure class tabled here. The standard also has PN 14 (PN 16 drilling) and PN 35 (PN 21 drilling).
Select a class to switch. All dimensions in mm.
Source: AS 4087:2011 incorporating Amendments 1 and 2 — Metallic flanges for waterworks purposes. Verify against your physical flange.
ASME B16.21 — Non-Metallic Flat Gaskets
Gasket dimensions for ASME B16.5 flanges. Class 150, Class 300 and Class 600 are the primary pressure classes for flat gaskets. Sizes shown as NPS with DN equivalent in parentheses. All dimensions converted to mm.
Select a class to switch. All dimensions in mm.
Source: ASME B16.21-2021 — Nonmetallic Flat Gaskets for Pipe Flanges. Dimensions converted from inches to mm. Verify against your physical flange.
EN 1514 — European Standard
EN 1514 covers gaskets for EN 1092-1 flanges — the European equivalent of the ASME B16.5 system. PN 10 and PN 16 are the two pressure-nominal ratings most commonly seen in Australian applications. Some smaller sizes share dimensions between PN classes — differences appear at larger diameters.
Select a PN class to switch. All dimensions in mm.
Source: EN 1514-1 — Flanges and their joints. Dimensions of gaskets for PN-designated flanges (EN 1092-1). Verify against your physical flange.
Can't Find Your Size?
Look It Up in the Gasket Generator
The tables above cover the four standards we see most. Our Gasket Generator carries the rest: seven standards including the larger AS 4087 sizes, the full AS 2129 table set, BS 3063, BS 4865, and JIS. Two ways to find a round flange:
Know the standard?
Pick the Round shape, open the Lookup tab, then filter by system, rating, and DN, or type a standard into the search box. Click a result to load its dimensions.
Only have measurements?
Pick the Round shape, type whatever dimensions you have into Specify, then read the Nearest tab. It ranks the closest catalogued standards and flags when a match is the right shape but the wrong size.
The generator is a reference aid, not a specification. The nearest-match score is a weighted estimate, so always confirm against the physical flange or the current published standard before ordering.
Search the CatalogueCustom & Non-Standard Gaskets
Non-standard profiles can be reviewed from a controlled drawing or verified measurements. Confirm material, thickness, finished dimensions, tolerances, quantity and required evidence; the available fabrication route and size range are confirmed at quotation.
If your flange doesn't match any standard table, or you need a gasket for a non-standard PCD, bolt pattern, or irregular shape, send us your measurements or drawing and we'll quote it.
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