Custom Machined Flanges

A Flange Has to Match and Seal

A flange exists to join two things and, often, to seal them. So its value lives in three features: the bolt pattern (which must match the mating flange), the centre bore (which must line up with the pipe, shaft or port), and the sealing face (which must be flat for a gasket or O-ring to hold). Machined from solid, we hold all three precisely — and across a batch, so every flange is interchangeable.

Custom Flange Specifications

Attribute	Capability
Materials	6061 aluminium, mild & alloy steel, 304/316 stainless
Bolt pattern	Standard or bespoke; true position from a common datum
Sealing face	Flat; raised face, O-ring groove or recess on request
Centre bore	Bored/turned concentric to the bolt circle
Tolerance	±0.025 mm on critical features; controlled flatness
Quantity	One-off to interchangeable batch

Flange Standards & Pressure Classes

Need a flange to a recognised standard? We machine to the common ones — and, unlike the forged-flange stockists, we also make the non-standard, adapter and obsolete flanges they can't supply from a catalogue.

Standard	Classes / ratings
ASME / ANSI B16.5	NPS ½–24″ · Class 150 / 300 / 600 / 900 / 1500 / 2500
ASME B16.47 (A/B)	Large-diameter flanges
DIN / EN 1092-1	PN 6 / 10 / 16 / 25 / 40
JIS	5K / 10K / 16K / 20K
Face types	Raised Face (RF) · Flat Face (FF) · Ring-Type Joint (RTJ)

Standard pipe-flange materials such as A105 carbon steel and A182 F304/F316 stainless are available with certs. Working to a drawing, a standard callout, or a sample — we match it.

Flange Types We Machine

• Pipe & port flanges — to match an existing pattern
• Shaft / bearing flanges — concentric pilots and bores
• Blind & closure flanges — sealed ends
• Adapter flanges — converting one bolt pattern to another
• Motor / pump mounting flanges — with register spigots

Stainless Steel, Steel & Aluminium Flanges

Material is usually the first call on a flange. A stainless steel flange in 304 or 316/316L is the default wherever corrosion, washdown, hygiene or a marine or chemical medium is involved — and a stainless steel pipe flange machined from solid avoids the porosity of a cheap casting. A steel flange (mild or alloy, A105-grade carbon steel) gives strength at lower cost for structural and non-corrosive duty, while a 6061 aluminium flange keeps weight down on non-pressure mounts and brackets. Tell us the pressure, medium and environment and we machine the metal flange to suit, with a material certificate on request.

Matching & Sealing

Send the bolt circle diameter, hole count, hole size and centre bore — or the mating/old flange itself — and we machine a flange that bolts straight on. The sealing face is machined flat and to the finish a gasket needs, with O-ring grooves or raised faces added as required. Flatness and hole position are verified on inspection. See our bolt-pattern-matched flange batch for how we hold position across a run.

Frequently Asked Questions