Buy Flanges Online in Australia
What is a pipe flange?
A pipe flange is a disc-shaped end fitting welded or threaded onto a pipe end. Two flanges bolted face-to-face with a gasket between them form a flanged joint — a connection that can be disassembled for maintenance without cutting the pipe. Flanges are used at valve connections, pump connections and equipment nozzles. AIMS Industrial supplies pipe flanges in carbon steel and 316L stainless steel.
What are the main types of pipe flanges?
Weld neck flanges have a long tapered hub butt-welded to the pipe — the most robust type for high-pressure and cyclic service. Slip-on flanges slide over the pipe and are fillet-welded at the bore and face. Blind flanges close the end of a pipe or vessel. Threaded flanges screw onto a threaded pipe end without welding.
Are flanges of different standards interchangeable?
No — flanges manufactured to different standards have different bolt circles, bolt counts and dimensions. A flange to one standard will not bolt up to a flange of another standard at the same nominal size. Always confirm the standard, nominal size, pressure class and face type before ordering replacements.
Pipe Flange Standards — Quick Reference
Pipe flanges are specified by face type, pressure rating and dimensional standard. Australian water industry uses AS 4087 (Table-D and Table-E). Process pipework typically uses ANSI/ASME B16.5 (Class 150 and higher). European-derived process equipment uses BS EN 1092 / DIN PN ratings. Flanges from DIFFERENT standards do NOT bolt together — verify before ordering replacements.
| Standard | Common Rating | Bolt Circle PCD (DN100 example) | Typical Use |
|---|---|---|---|
| AS 4087 Table-D | Up to 6.9 bar | 180 mm (8-bolt) | AU water supply, irrigation, fire service |
| AS 4087 Table-E | Up to 13.8 bar | 190 mm (8-bolt) | AU higher-pressure water, municipal mains |
| ANSI B16.5 Class 150 | Up to 19.7 bar (ambient) | 190.5 mm (8-bolt) | Process plant, chemical, oil & gas, imported skid equipment |
| ANSI B16.5 Class 300 | Up to 51.1 bar (ambient) | 200 mm (8-bolt) | Higher-pressure process, steam, high-pressure water |
| BS EN 1092 PN16 | Up to 16 bar | 180 mm (8-bolt) | European chemical & process equipment |
| BS EN 1092 PN25 | Up to 25 bar | 190 mm (8-bolt) | European higher-pressure process |
| JIS B2220 10K | Up to 10 bar | 175 mm (8-bolt) | Japanese-origin equipment, marine, Asian market machinery |
Flanges of different standards have DIFFERENT bolt circles — they will NOT mate. When matching to existing pipework, identify the standard from existing bolt count + bolt circle measurement. For gaskets matched to each flange standard, see gaskets and our spiral wound gasket guide. For flexible flanged connections, see rubber bellows.
Pipe Flanges
Pipe flanges are the disc-shaped end fittings welded or threaded onto pipe ends to create a bolted connection point. Two flanges bolted face-to-face with a gasket between them form a flanged joint — a connection that can be disassembled for maintenance and component access without cutting the pipe. Flanges are used at valve connections, pump connections, equipment nozzles, and wherever the piping system must be periodically broken for service. AIMS Industrial supplies pipe flanges in carbon steel and stainless steel for industrial piping applications across Australia.
Types of Pipe Flanges
- Weld neck flanges: The most robust flanged connection — a long tapered hub is butt-welded to the pipe end, providing a smooth bore transition and transferring stress from the flange into the pipe wall gradually. The preferred type for high-pressure, high-temperature, and cyclic load service where fatigue resistance is important.
- Slip-on flanges: Slide over the pipe and are fillet-welded at the bore and face. Easier to align and fit than weld neck flanges, but lower pressure and fatigue resistance. The most common type for moderate-service industrial piping.
- Blind flanges: Solid disc that closes the end of a pipe, nozzle, or valve. Used to blank off the end of a pipe run, provide a future connection point, or close a vessel nozzle during hydrostatic testing.
- Threaded flanges: Screwed onto a threaded pipe end — no welding required. For small-bore, low-pressure applications where threading is practical and welding is undesirable or unavailable.
Pressure Class and Material Selection
Flange pressure class (ANSI Class 150, 300, 600, etc.) must match the system pressure and temperature envelope. Carbon steel flanges (A105N or equivalent) suit general industrial service including steam, water, oil, and gas. 316L stainless steel flanges are specified for corrosive services including acids, chloride environments, and food processing. Matching the flange specification to the pipe and the service conditions is not optional — a mismatched flange is an unrated, potentially dangerous component. For flange selection and specification guidance, contact our team.
Flange Selection and Compliance
Selecting the correct flange requires confirming the nominal pipe size (NPS or DN), the pressure class, the face type (raised face, flat face, or ring-type joint), and the material grade. In Australian process industries, both ASME B16.5 and AS 4087 flanges are in use — these standards differ in detail, and mixing standards within a flanged joint is not permitted. AIMS Industrial stocks flanges in carbon steel (A105N) and 316L stainless steel in common nominal sizes and pressure classes, and our team can assist with specification for new and replacement applications.
People Also Ask — Flanges
Q: What is a pipe flange?
A pipe flange is a disc-shaped end fitting welded or threaded onto a pipe end. Two flanges bolted face-to-face with a gasket between them form a flanged joint — a bolted connection that can be disassembled for maintenance and component access without cutting the pipe.
Q: What are the main types of pipe flanges?
Weld neck flanges have a long tapered hub butt-welded to the pipe — the most robust type for high-pressure and cyclic service. Slip-on flanges slide over the pipe and are fillet-welded front and back. Blind flanges close the end of a pipe or vessel. Threaded flanges screw onto a threaded pipe end without welding, suited to lower-pressure piping where welding isn't practical.
Q: Are flanges of different standards interchangeable?
No. Flanges manufactured to different standards — such as AS 4087, ANSI B16.5, and BS EN 1092 — have different bolt circle diameters, bolt counts, and face dimensions even at the same nominal size. A flange to one standard will not bolt up to a flange of another standard. Always confirm the standard, nominal size, pressure class, and face type before ordering replacement flanges.
Q: What is the difference between AS 4087 Table-D and Table-E flanges?
Both are Australian water industry flanges. Table-D flanges suit pressures up to 6.9 bar, with a bolt circle PCD of 180 mm at DN100. Table-E flanges suit pressures up to 13.8 bar with a wider PCD of 190 mm at DN100 — the higher bolt circle diameter provides additional clamping force for higher-pressure service.
Q: How do you identify an unknown flange standard on site?
Count the bolt holes and measure the bolt circle diameter. These two values together with the nominal pipe size will typically identify the standard — for example, DN100 with 8 bolts on a 180 mm PCD points to AS 4087 Table-D, while 8 bolts on a 190 mm PCD points to Table-E. Material (carbon steel vs stainless) and face type (raised face, flat face) help narrow it further.
Q: What is the difference between a raised face and flat face flange?
Raised face (RF) flanges have a small raised annular section around the bore where the gasket sits — this concentrates bolt clamp load on the gasket ring for better sealing. It's the industry standard for steel piping in general chemical, oil and gas, and process service. Flat face (FF) flanges have no raised section — the gasket covers the full face inside the bolt circle. Flat face is used with brittle-body flanges (cast iron pump casings, some GRE composites) where a raised face would risk cracking the mating body under bolt load. Never bolt an RF flange to a cast iron FF flange without checking the mating body specification.
Q: What are ANSI flange pressure classes 150#, 300#, 600#?
ANSI B16.5 pressure classes are numeric ratings — 150#, 300#, 600#, 900#, 1500#, 2500# — defining the pressure-temperature rating envelope for the flange. The number is roughly the working pressure in psi at 500°F for carbon steel, but the actual rating varies with material and temperature. Class 150 covers general water, air and low-pressure service; Class 300 is common in mid-pressure steam and process piping; Class 600 and above cover high-pressure oil and gas and superheated steam. Higher classes have thicker flanges, more bolts and larger bolt diameters at the same nominal size.
Q: How do I select the right gasket for a flanged joint?
Match the gasket material to the fluid and temperature: compressed non-asbestos fibre for general water, oil and low-pressure steam; PTFE (Teflon) for chemical service; graphite for high-temperature steam; spiral-wound (metal-and-filler construction) for high-pressure or cyclic thermal service. Match the gasket dimensions to the flange face type — full-face gaskets for FF flanges, ring gaskets for RF flanges. Compression: aim for 15-30% of gasket thickness under bolt load; over-compression damages the gasket, under-compression leaks. See our spiral wound gasket guide for higher-pressure applications.
Q: What flange materials suit corrosive service?
For general industrial service, carbon steel (ASTM A105 forged, ASTM A182 wrought) is the default. Stainless 304L handles mild corrosive service and food-grade applications. Stainless 316L handles marine, saltwater and moderate chemical exposure. For aggressive chemical service — hot acids, chlorides, high-temperature process fluids — duplex stainless (2205), super-duplex (2507), Hastelloy or Monel are specified. Always match the flange material grade to the piping material grade — mixing materials in a bolted joint creates galvanic corrosion risk. For AS 4087 water industry flanges, ductile iron (AS 2280) is standard with epoxy or fusion-bonded coating for buried service.
Q: What is the difference between AS 2129 and AS 4087?
Both are Australian flange standards but serve different industries. AS 2129 covers general industrial steel flanges (Tables D, E, F, H and higher pressure classes) — the older standard, still widely used in process and manufacturing plant. AS 4087 covers water industry ductile iron and steel flanges for pressures up to Class 21 (2100 kPa) — used on water distribution, sewage and irrigation piping. AS 4087 Table D and Table E dimensions match AS 2129 Table D and Table E for direct bolt-up compatibility, but AS 4087 covers a narrower pressure range and includes water-specific material grades. Always check which standard the existing pipeline was designed to before ordering replacements.