OEM manufacturer ASME B16.9 · ASME B16.25
Butt Weld Eccentric Reducers — ASME B16.9
An eccentric reducer joins two pipe sizes with one side kept flat, so the top or bottom of the line stays level. Teshi Group manufactures eccentric reducers to ASME B16.9 in carbon, low-temperature, alloy and stainless steels, with each end matched to its pipe schedule.
Also called: butt weld eccentric reducer, ecc reducer, ERD, reducer eccentric
What is an Eccentric Reducer?
An eccentric reducer is a butt weld fitting whose small end is offset from the centre line of the large end, giving one flat side. Installed flat side up on a horizontal pump suction, it prevents air pockets that cause cavitation. Installed flat side down on a pipe rack, it keeps a common bottom of pipe for support and drainage. Lengths and size combinations follow ASME B16.9, the same as concentric reducers.
Key features
- One flat side for level top or bottom of pipe
- Size combinations and lengths per ASME B16.9
- Different schedules on large and small ends on request
- Ends bevelled to ASME B16.25
Specification
| Supply | OEM manufacturer — Teshi Group, India |
|---|---|
| Standard | ASME B16.9 |
| Size range | Large/small end combinations as tabulated in ASME B16.9 (up to NPS 48") |
| Wall thickness | Matched to the connecting pipe schedule — Sch 5S, 10S, 40, STD, 80, XS, 160, XXS (ASME B36.10M / B36.19M) |
| Ends | Bevelled for butt welding per ASME B16.25 |
| Construction | Seamless (formed from pipe) or welded (formed from plate), per the grade designation, e.g. WPB / WPBW, WP316-S / WP316-W |
| Materials — carbon steel | ASTM A234 WPB, WPC (seamless and welded WPB-W) |
| Materials — high-yield carbon steel | ASTM A860 WPHY 42, 46, 52, 56, 60, 65, 70 (MSS SP-75) |
| Materials — low-temperature carbon steel | ASTM A420 WPL3, WPL6, WPL8, WPL9 |
| Materials — alloy steel (Cr-Mo) | ASTM A234 WP1, WP5, WP9, WP11 Cl 1 / 2 / 3, WP12 Cl 1 / 2, WP22 Cl 1 / 3, WP91, WP92 |
| Materials — stainless steel | ASTM A403 WP304, WP304L, WP304H, WP309, WP310S, WP316, WP316L, WP316H, WP316Ti, WP317, WP317L, WP321, WP321H, WP347, WP347H (seamless S, welded W / WX) |
| Materials — 904L and 6Mo | 904L (UNS N08904, ASTM A403 / B366); 254 SMO / 6Mo (ASTM A403 WPS31254); AL-6XN (UNS N08367, ASTM B366) |
| Materials — duplex stainless steel | ASTM A815 WPS31803, WPS32205 (2205) |
| Materials — super duplex stainless steel | ASTM A815 WPS32750 (2507), WPS32760, WPS32550 |
| Materials — nickel alloys | ASTM B366: Nickel 200 / 201 (N02200 / N02201), Monel 400 (N04400), Inconel 600 (N06600), Inconel 625 (N06625), Incoloy 800 / 800H / 800HT (N08800 / N08810 / N08811), Incoloy 825 (N08825), Hastelloy C276 (N10276), Hastelloy C22 (N06022), Hastelloy B2 / B3 (N10665 / N10675), Alloy 20 (N08020) |
| Materials — titanium | ASTM B363 WPT1, WPT2, WPT7, WPT12; Grade 5 (Ti-6Al-4V) against order |
| Materials — copper-nickel | Cu-Ni 90/10 (UNS C70600) and 70/30 (UNS C71500), made from ASTM B466 / B467 pipe (EEMUA 146 dimensions on request) |
| Grade availability | Every grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades. |
| Testing | Visual and dimensional inspection; PMI on alloy and stainless grades; hardness check; RT, UT, MPI or DPT and IGC tests when specified |
| Documents | EN 10204 3.1 mill test certificate; 3.2 / third-party inspection when the order specifies; dimensional inspection report; IBR certification for boiler/steam service when specified |
Applications
- Horizontal pump suction lines
- Pipe racks with a common bottom of pipe
- Slurry and drain lines
- Cooling water and process piping
Flat side up vs flat side down
On a pump suction, an eccentric reducer is installed flat side up (top flat) so vapour or air cannot collect ahead of the pump. On pipe racks and lines that must drain, it is installed flat side down (bottom flat) so the bottom of pipe stays at one elevation and liquid does not pool. The orientation is shown on the isometric and should be checked at installation.
Technical data sheets
Dimensions & weights
FAQ
Eccentric Reducer: common questions
What is the offset of an eccentric reducer?
The offset is half the difference between the inside diameters of the large and small ends, so one side stays flat. The exact value depends on sizes and schedules.
Is an eccentric reducer the same length as a concentric one?
Yes. ASME B16.9 gives the same end-to-end length for concentric and eccentric reducers of the same large-end and small-end combination, so they can be interchanged in layout.
Which way up does an eccentric reducer go on a pump suction?
Flat side up, so that air or vapour cannot collect at the top of the reducer and be drawn into the pump, which can cause cavitation and loss of performance.
Can you supply eccentric reducers in stainless steel?
Yes. ASTM A403 WP304L and WP316L eccentric reducers are supplied in Sch 10S, 40S and heavier schedules, with PMI reports and EN 10204 3.1 certificates.
Need a size or grade not listed here?
Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.
Send us your specificationTraceability
From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
Quick RFQ
Quote for Eccentric Reducer in 24–48 hours
More butt weld fittings
All butt weld fittingsButt Weld Pipe Cap
ASME B16.9 · ASME B16.25
View productButt Weld FittingsStub End
ASME B16.9 · MSS SP-43
View productButt Weld FittingsSwage Nipple
MSS SP-95 · ASME B1.20.1
View productButt Weld Fittings90° Butt Weld Elbow
ASME B16.9 · ASME B16.25
View productButt Weld Fittings45° Butt Weld Elbow
ASME B16.9 · ASME B16.25
View productButt Weld Fittings180° Return Bend
ASME B16.9 · ASME B16.25
View product