Reducing Flanges

On a standard flange, every dimension — the bore, the outer diameter, the bolt circle, the raised face — is sized to match one single nominal pipe size throughout. A reducing flange is genuinely different: its outer dimensions, bolt circle, and bolt hole pattern are machined to match a larger nominal pipe or flange size, so it bolts up to a same-larger-size mating flange using a completely standard bolt pattern — but its bore is machined to the smaller pipe size that actually needs to connect there.

This genuinely combines two functions into one component. Normally, transitioning pipe diameter requires a separate concentric or eccentric reducer fitting welded into the pipe run, plus a standard flange at whatever size is needed at that connection point. A reducing flange eliminates the reducer fitting entirely by building the diameter transition directly into the flange itself, at the exact point the bolted connection already needs to happen anyway — the size transition happens there for free, at no extra weld joint.

A genuine, honest limitation follows directly from where this transition physically happens. Because it occurs right at the bore of the reducing flange — a very short axial distance — the fluid flow experiences a genuinely more abrupt change in cross-sectional area than a separate reducer fitting would provide. A standalone concentric reducer is typically manufactured with a longer, tapered transition length specifically to minimize turbulence and pressure drop, while a reducing flange’s transition is confined to the flange’s own thickness. This can create more turbulence and a higher, less predictable pressure drop at that point than a properly tapered separate reducer would — an honest, real hydraulic trade-off worth flagging for flow-sensitive or high-velocity service.

Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our reducing flange range is manufactured and verified for bore concentricity and bolt pattern accuracy under our ISO 9001:2015 quality system.