Concentric Reducer - Butt-Weld Pipe Fitting
Our concentric butt-weld reducer transitions between two pipe sizes along a single common centreline. The symmetrical taper keeps flow velocity uniform around the full circumference of the bore, making it the right choice for vertical risers, pump suction lines and gravity-fed systems where air pockets must be avoided.
Each reducer is supplied with factory-machined weld-end bevels to ASME B16.25 for full-penetration butt welding. Full heat-number traceability and EN 10204 3.1 material test certificates are available to satisfy UK site quality requirements.
Standards & Materials
Produced to BS EN 10253-2 and ASME B16.9 in a choice of carbon and stainless steel grades to suit your operating conditions.
| Attribute | Specification |
|---|---|
| Manufacturing Standard | BS EN 10253-2 / ASME B16.9 |
| Carbon Steel | ASTM A234 WPB |
| Stainless Steel | ASTM A403 WP304 / WP304L / WP316 / WP316L |
| Special Grades | Duplex & Super Duplex (UNS S31803 / S32205 / S32750), Alloy 20, Inconel 625 / 825, Monel 400, Hastelloy C-276 - available on request |
| Fabrication | Seamless or welded |
| Weld-End Bevel | ASME B16.25, 37.5° half-angle |
| Test Pressure | Up to 1 500 psi (103 bar) |
Dimensions & Sizes
Available across a broad range of size combinations up to 24" in schedules 10, 40 and 80. The table below shows representative ASME B16.9 overall length H for common concentric reducer size combinations.
| Large End NPS | Small End NPS | Overall Length H (mm) |
|---|---|---|
| 3/4" | 1/2" | 38 |
| 1" | 1/2" | 38 |
| 1" | 3/4" | 38 |
| 1-1/2" | 3/4" | 64 |
| 1-1/2" | 1" | 64 |
| 2" | 1" | 76 |
| 3" | 2" | 89 |
| 4" | 3" | 102 |
| 6" | 4" | 140 |
| 8" | 6" | 178 |
| 10" | 8" | 229 |
| 12" | 10" | 330 |
Performance & Benefits
The concentric, symmetrical taper ensures uniform flow velocity around the full bore, preventing dead zones and air accumulation on vertical runs. This balanced geometry also distributes mechanical loads evenly across the weld joints, reducing stress concentration compared with offset (eccentric) designs in vertical pipework.
Typical Applications
Commonly specified for vertical pump discharges, gravity-fed lines, stack-mounted plant, boiler feed systems and HVAC risers across the UK where concentric alignment is required for proper drainage and air elimination.
Quality Assurance & Traceability
Every fitting is manufactured to BS EN 10253-2 and ASME B16.9 and supplied with full material traceability and EN 10204 Type 3.1 test certificates. Heat numbers are recorded throughout production to support inspection, QA and UK project-compliance requirements.
Supply & Delivery
Stocked at our Sheffield, UK facility and delivered nationwide across England, Scotland and Wales. We offer fast dispatch from stock with tracked UK delivery to site, and next-day options for common sizes.
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Which sizes and schedules are available?
Available from 1/2" (DN15) to 24" (DN600) in schedule 10, 40 and 80, in both metric and imperial sizes to suit UK installations.
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When should I use a concentric reducer instead of an eccentric reducer?
Use a concentric reducer on vertical lines, pump suction risers and any installation where the pipe centreline must remain aligned. An eccentric reducer (flat-top or flat-bottom) is preferred on horizontal runs where you need to prevent air entrapment (flat top) or ensure complete drainage (flat bottom). Concentric reducers are also easier to fabricate and align on site.
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Can you provide material certificates?
Yes. Material test certificates and full traceability documentation are available with every order, to project and quality-management requirements.
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Do you deliver across the UK?
We deliver nationwide throughout England, Scotland and Wales, with fast dispatch from stock and tracked deliveries to site.