Concentric & Eccentric Reducers
Butt-weld reducers change pipe bore between two schedules or sizes: concentric for vertical symmetry, eccentric with one flat side for pipe racks and pump suctions. NPS 1/2" to 48", any standard reduction combination.
Concentric & Eccentric Reducers
Reducers join two different pipe sizes while keeping flow characteristics smooth. The concentric type tapers symmetrically around the pipe axis and is used at vertical lines and pump discharges; the eccentric type keeps one side flat (TOP or FOS alignment) so pipe racks hold a constant elevation and gas lines avoid liquid traps. CREATEEL supplies both types from 1/2"×3/8" up to 48"×36".
Seamless reducers are hot-formed in one piece from pipe; welded reducers are rolled from plate with a single longitudinal seam, 100% radiographed. Concentricity, taper length and flatness of eccentric pieces are inspected piece by piece against ASME B16.9.
Every CREATEEL fitting is shipped with full heat-number traceability from raw material certificate to the stamped marking on the piece itself. Dimensional reports, heat treatment charts and EN 10204 3.1 inspection certificates are issued as standard, with 3.2 certification by third-party inspection (SGS, BV, TÜV) available on request before shipment.
Technical Specifications
Applicable Standards
| Standard | Scope | Note |
|---|---|---|
| ASME B16.9 | Butt-welding fittings (reducers) | Governing dimensions & tolerances |
| MSS SP-95 | Swaged reducers & increasers | Small-bore swaged transitions |
| EN 10253-2 / -4 | Wrought fittings, type A & B | European; -2 carbon, -4 alloy/special |
| GB/T 12459 | Steel butt-welding fittings | Chinese national |
| GOST 17378 | Concentric & eccentric reducers | Russian |
| JIS B 2312 / B 2313 | Steel butt-welding fittings | Japanese |
| ISO 3419 | Non-alloy & alloy steel fittings | International |
Reducer Dimensions (ASME B16.9)
| NPS (large × small) | Large End OD (mm) | Small End OD (mm) | Center-to-End H (mm) |
|---|---|---|---|
| 1″ × 1/2″ | 33.4 | 21.3 | 25 |
| 1-1/4″ × 3/4″ | 42.2 | 26.7 | 25 |
| 2″ × 1″ | 60.3 | 33.4 | 38 |
| 2-1/2″ × 1-1/2″ | 73.0 | 48.3 | 44 |
| 3″ × 2″ | 88.9 | 60.3 | 44 |
| 4″ × 3″ | 114.3 | 88.9 | 51 |
| 6″ × 4″ | 168.3 | 114.3 | 64 |
| 8″ × 6″ | 219.1 | 168.3 | 76 |
| 10″ × 8″ | 273.0 | 219.1 | 89 |
| 12″ × 10″ | 323.8 | 273.0 | 102 |
| 16″ × 12″ | 406.4 | 323.8 | 127 |
| 20″ × 16″ | 508 | 406.4 | 152 |
| 24″ × 20″ | 609.6 | 508 | 178 |
Eccentric reducers per ASME B16.9 are supplied with long face (H1) and short face (H2) dimensions; sizes and schedules on request. All dimensions are nominal and for reference — confirm against the governing standard before ordering.
Material Grades
| Family | Grade | Spec |
|---|---|---|
| Carbon steel | A234 WPB / WPC | ASTM A234 |
| Low-temperature | A420 WPL6 / WPL3 / WPL9 | ASTM A420 |
| Alloy (Cr-Mo) | A234 WP11 / WP22 / WP91 | ASTM A234 |
| Stainless | A403 WP304 / 304L / 316 / 316L / 321 | ASTM A403 |
| Duplex / super | A815 WPS31803 / WPS32205 | ASTM A815 |
| Large-diameter (welded) | A860 WPHY 42–70 | ASTM A860 |
Coating & Surface Treatment
- Black / varnished — mill finish with anti-rust oil for general service.
- Hot-dip galvanized (HDG) to ASTM A153 / ISO 1461 for atmospheric corrosion resistance.
- 3PE / FBE external coating for buried and subsea pipelines.
- Internal epoxy lining for water, slurry and food-grade service.
- Pickled & passivated stainless for hygienic and corrosive duty.
- Oiled / bare, end-capped for short-term export storage.
Packing & Shipping
- Plywood cases or pallets, seaworthy export packing.
- End caps / branch protection and waterproof wrapping.
- Bundle strapping with lifting tags and piece marking.
- EN 10204 3.1 mill test certificates; 3.2 with SGS / BV / TÜV on request.
- MOQ 5 t per item; lead time 15–30 days depending on grade and size.
Types & Range
Materials & Standards
A234 WPB, WP11/WP22/WP91, A420 WPL6 and A403 stainless grades — selected to match the two pipe runs being joined. Wall thickness is specified at the large end per B16.9.
Standards in brief: ASME B16.9 for dimensions and tolerances, MSS SP-95 for swages; ends per ASME B16.25; EN 10204 3.1 / 3.2 certification available.
Manufacturing Process
Hot die-forming line for ASME B16.9 concentric and eccentric reducers — seamless one-piece bodies, smooth transition taper.
Material Selection
Seamless pipe in the larger size and matching grade; plate for large welded reducers.
Cutting
Blanks cut to length with allowance for the forming stroke.
Induction Heating
One end zone heated to ~1000°C for controlled wall distribution.
Hot Forming
Pushed/pressed through a tapering die — concentric stays symmetrical, eccentric forms with the flat offset.
Welded Reducer Route
Large sizes rolled from plate, longitudinal seam SAW-welded and 100% radiographed.
End Machining
Both ends faced and beveled 37.5° per ASME B16.25.
Heat Treatment & NDT
Normalizing as required; UT wall check, MT on welded seams.
Marking & Packing
Large×small sizes and heat number stamped; paired and crated to avoid face damage.
Applications
Reducers change line size cleanly across oil & gas, water, power and process systems worldwide.
Pipeline & Gathering Systems
Concentric and eccentric reducers transition trunklines and station piping between block-valve, metering and pigging sizes — no welded transition piece required.
✓ ASME B16.9 / API 5L
Water Supply & Treatment
Size changes in potable-water, stormwater and sewage networks, with smooth bores that limit head loss across the transition.
✓ EN 10253 / GB/T 12459
Power Plant & Boiler Piping
Feedwater, condensate and auxiliary lines use reducers to step between pump and header sizes in thermal and nuclear stations.
✓ A234 WP11 / ASME B31.1
Process & Petrochemical Plants
Alloy and stainless reducers for corrosive, low-temperature and high-purity services, with NACE sour-service options.
✓ A403 WP316L / NACE
Marine & Offshore
Hull, ballast and cargo piping where low-temperature grades resist Arctic and splash-zone duty on vessels and platforms.
✓ A420 WPL6
HVAC & Building Services
Risers and plant-room piping in commercial buildings and district-energy loops, where tidy transitions speed installation.
✓ A234 WPB
Frequently Asked Questions
Concentric or eccentric for my line?
Can you make non-standard reductions?
How is wall thickness defined?
What size range do you supply?
What materials are available?
Seamless or welded reducers?
How is quality controlled?
What surface finishes are available?
What is your MOQ and lead time?
What marking and documentation come with the goods?
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