Reducers (Concentric & Eccentric)
Giriraj Impex is a manufacturer, stockist, supplier and exporter of concentric and eccentric reducers – butt-weld reducers to ASME B16.9 and MSS SP-43. We manufacture reducers in stainless steel, carbon steel, alloy steel, duplex and super duplex steel and nickel alloys, seamless and welded, from ¾" × ½" to 48" NB, in schedules from Sch 5S to XXS, with mill test certificates.
A reducer joins pipes of different sizes. Concentric reducers keep the pipe centrelines in line; eccentric reducers keep one side of the pipe flat.
Concentric and eccentric reducers
A concentric reducer is cone shaped, with both ends on the same centreline. It is used in vertical lines and in horizontal lines where trapping of vapour or liquid does not matter. An eccentric reducer has one side flat, so the centrelines are offset. The flat side is placed on top or bottom to suit the service.
When to use an eccentric reducer
- Pump suctions – eccentric reducers are installed flat side up at pump inlets, so that no vapour pocket can collect at the top of the reducer and cause cavitation.
- Pipe racks – flat side down (bottom of pipe level) keeps the pipe bottom at a constant elevation on supports.
- Drainable lines – flat side down lets liquid drain without pockets in gas or steam lines.
- Slurry lines – flat side down avoids solids settling at the change of size.
Concentric reducers are used in vertical lines, on pump discharges and wherever the offset is not needed.
On pump suctions the eccentric reducer is normally placed directly at the pump nozzle, so the straight pipe upstream keeps the flow steady. Getting the orientation wrong – flat side down on a suction line – can trap air and reduce pump performance, so it should be marked clearly on isometrics and checked during installation.
Specifications
| Item | Details |
|---|---|
| Dimensional standards | ASME B16.9, MSS SP-43 (light wall), MSS SP-75 |
| Sizes | ¾" × ½" to 24" NB seamless; up to 48" NB welded |
| Schedules | Sch 5S, 10S, 40S, 80S, 10 to 160, STD, XS, XXS; different schedules at each end on request |
| Construction | Seamless or welded |
| Ends | Bevelled to ASME B16.25 |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Reducer lengths
| Large end NPS | OD at bevel | Length (H) |
|---|---|---|
| ¾ | 26.7 | 38 |
| 1 | 33.4 | 51 |
| 1¼ | 42.2 | 51 |
| 1½ | 48.3 | 64 |
| 2 | 60.3 | 76 |
| 2½ | 73.0 | 89 |
| 3 | 88.9 | 89 |
| 4 | 114.3 | 102 |
| 5 | 141.3 | 127 |
| 6 | 168.3 | 140 |
| 8 | 219.1 | 152 |
| 10 | 273.1 | 178 |
| 12 | 323.9 | 203 |
| 14 | 355.6 | 330 |
| 16 | 406.4 | 356 |
| 18 | 457.0 | 381 |
| 20 | 508.0 | 508 |
| 24 | 610.0 | 508 |
The length is the same for concentric and eccentric reducers and for all small-end sizes of a given large end.
Dimensions are from ASME B16.9 and are given for guidance; always check the current edition and the project specification. More fitting dimensions are in the butt-weld fitting dimensions chart.
Reducer materials
- Stainless steel pipe fittings – ASTM A403 WP304/304L, WP316/316L, WP321, WP347.
- Carbon steel pipe fittings – ASTM A234 WPB, WPC; A420 WPL6; MSS SP-75 WPHY.
- Alloy steel pipe fittings – ASTM A234 WP5, WP9, WP11, WP22, WP91.
- Duplex steel pipe fittings – ASTM A815 WPS31803, WPS32205.
- Super duplex pipe fittings – ASTM A815 WPS32750, WPS32760.
- Inconel pipe fittings – ASTM B366, and other nickel alloys.
All fitting materials are on the pipe fittings page.
How we manufacture reducers
Seamless reducers are made by pressing a length of pipe in dies, reducing one end (for small-end forming) or expanding the other. Eccentric reducers are pressed in offset dies. Large reducers are rolled from plate and welded. After forming, reducers are heat treated as required, bevelled and checked for dimensions and wall thickness, and each is marked with material, sizes, schedule and heat number.
Ordering reducers
Please give the material, type (concentric or eccentric), large and small end sizes, schedule at each end, seamless or welded construction, quantity and any testing or inspection requirement.
Frequently Asked Questions
A concentric reducer keeps both ends on the same centreline; an eccentric reducer has one flat side, so the centrelines are offset.
Installed flat side up, it prevents vapour or air pockets collecting at the pump inlet, which could cause cavitation.
Under ASME B16.9, a reducer with a 4" large end has a length of 102 mm.
Yes. Reducers can be supplied with a different wall schedule at each end to match the connecting pipes.
ASME B16.9 covers concentric and eccentric butt-weld reducers.
In vertical lines, on pump discharges and wherever an offset in the pipe centreline is not needed.
Request a Quote for Reducers (Concentric & Eccentric)
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.
Inconel® is a trademark of Special Metals Corporation.