When should I use a concentric reducer vs an eccentric reducer?

Concentric reducers have the same centreline — used in vertical piping and gas/vapour lines where even flow distribution is needed. Eccentric reducers have one flat side — used in horizontal liquid lines (flat side up to prevent air pockets) and at pump suction (flat side down to avoid cavitation). Specifying the wrong type can cause operational problems.

EN 10253 Type B Available ASME B16.9

Buttweld Pipe Reducers

Concentric Reducers | Eccentric Reducers | ASME B16.9 | EN 10253

Manufacturer and exporter of concentric and eccentric buttweld reducers in all material grades. All sizes ½" – 48" × all standard reducing combinations. EN 10204 3.1/3.2 MTR. PED 2014/68/EU certified.

Request Quote EN 10253 Type B Guide

Range at a Glance

Types	Concentric & Eccentric
Size Range	¾"×½" – 48"×36"
Schedule	SCH 10 – XXS
ASME Std.	B16.9
EN Std.	EN 10253-1/-2/-3/-4
EN Type B	Available ✓
MTR	3.1 std / 3.2 on request

Concentric vs Eccentric Reducer — Selection Guide

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Concentric Reducer

Both ends share the same centreline axis. The transition is symmetrical — the pipe narrows equally on all sides.

Use when:

✓ Vertical piping (any orientation)
✓ Gas / vapour / steam lines (prevent condensate pockets)
✓ Overhead lines — symmetrical flow preferred
✓ Turbulent slurry service

Designated: Large NPS × Small NPS (e.g. 6"×4" CON)

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Eccentric Reducer

One side (flat side) is parallel to the pipe axis; the other side tapers. Used to maintain a level invert (bottom) or top of pipe.

Use when:

✓ Horizontal liquid piping — flat side up to prevent air pockets
✓ Pump suction — flat side down to prevent cavitation
✓ Gravity-drained lines requiring level invert
✓ Any horizontal line where air entrainment must be avoided

Designated: Large NPS × Small NPS (e.g. 6"×4" ECC)

Pump Suction Rule: Always use eccentric reducer flat-side-down at pump suction to prevent vapour accumulation which causes cavitation damage. This is a common field error — specifying concentric at pump suction or wrong orientation of eccentric can void pump warranties.