Pipe Flanges

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.