ASME B16.9 | Eccentric Pipe Reducers | Butt-Welding Pipe Fittings | NPS 1/2″–48″ | Carbon Steel, Stainless Steel, Duplex, Alloy & Nickel Alloys
Elite Buttweld Eccentric Reducers are factory-made pipe fittings used to connect pipes of different nominal diameters while maintaining an offset centerline. Unlike concentric reducers, one side of an eccentric reducer remains aligned while the opposite side is offset, creating a flat side that can be oriented flat-side-up (FSU) or flat-side-down (FSD) according to the piping arrangement.
Eccentric Reducers are commonly selected for horizontal piping, pump suction lines, drainage systems and other applications where control of liquid level, air pockets or pipe elevation is important.
| Parameter | Specification |
|---|---|
| Manufacturer | Elite |
| Product | Buttweld Eccentric Reducer |
| Primary Standard | ASME B16.9 |
| Configuration | Eccentric Reducer |
| Centerline | Offset between large and small ends |
| Size Range | NPS 1/2"–48" |
| Large End Size | As specified |
| Small End Size | As specified |
| Orientation | Flat Side Up (FSU) / Flat Side Down (FSD) |
| Construction | Seamless / Welded / Fabricated |
| End Connection | Butt Weld |
| Wall Thickness | SCH 5S, 10S, 20, 40S, STD, 80S, XS, 100, 120, 140, 160, XXS and custom |
| Dimensions | ASME B16.9 where applicable |
| End Preparation | ASME B16.25 where applicable |
| Material Standards | ASTM / ASME applicable specifications |
| Heat Treatment | According to material and applicable specification |
| Surface Finish | Pickled / Blasted / Polished / Coated / Project Specified |
| Inspection | Visual, dimensional, PMI, UT, RT, MT, PT, hardness and other NDE as specified |
| Documentation | MTC, EN 10204 3.1/3.2, inspection reports and project documentation |
| Configuration | Description | |
|---|---|---|
| Eccentric Reducer | Offset centerline between large and small ends | |
| FSU Reducer | Flat Side Up orientation | |
| FSD Reducer | Flat Side Down orientation | |
| Seamless Reducer | Seamless construction for applicable sizes/materials | |
| Welded Reducer | Welded construction for selected sizes/materials | |
| Fabricated Reducer | Custom large-diameter or special construction | |
| Note: The orientation of an eccentric reducer should be clearly specified on the piping isometric or purchase order, particularly for horizontal piping systems. | ||
ASME B16.9
Primary dimensional standard for factory-made wrought buttwelding fittings, including Eccentric Reducers.
ASME B16.25
Butt-welding end preparation.
ASTM / ASME Material Specifications
Applicable material standards according to the selected material and grade.
ASME B31.3 / B31.1
Process and power piping requirements, where applicable.
NACE MR0175 / ISO 15156
For sour-service applications when specifically required by the project.
ASME Section II
Material requirements where applicable to pressure equipment and project specifications.
Note: ASME B16.28 should not be listed as the primary standard for Eccentric Reducers. Current applicable wrought fitting dimensions are covered by ASME B16.9.
Carbon Steel
ASTM A234 WPB, WPC and applicable WPHY grades including WPHY 42, WPHY 46, WPHY 52, WPHY 60, WPHY 65 and WPHY 70.
Low Temperature Carbon Steel
ASTM A420 WPL3, WPL6 and other applicable grades.
Stainless Steel
ASTM A403 WP304/304L, WP316/316L, WP321/321H, WP347/347H and other applicable grades.
Duplex & Super Duplex
ASTM A815 grades including UNS S31803, S32205, S32750 and S32760.
Alloy Steel
ASTM A234 WP1, WP5, WP9, WP11, WP12, WP22 and WP91.
Nickel Alloys
ASTM B366 and applicable specifications for Nickel 200/201, Monel 400/K500, Inconel 600/601/625/800/825, Hastelloy C276 and Alloy 20.
Copper-Nickel Alloys
Applicable Cu-Ni grades including UNS C70600 and C71500.
Titanium
Applicable titanium grades manufactured to the relevant ASTM specification, including ASTM B363 where applicable.
Material selection is based on operating pressure, temperature, process fluid, corrosion conditions, mechanical requirements and applicable project specifications.
Standard Eccentric Reducer
A reducer with offset centerlines, providing a flat side for controlled pipe elevation or flow arrangement.
Flat Side Up (FSU)
The flat side is positioned on the upper side of the piping system. This configuration can be used where maintaining a level or avoiding a liquid pocket is required.
Flat Side Down (FSD)
The flat side is positioned on the lower side of the piping system, depending on the piping arrangement and drainage requirements.
Seamless Eccentric Reducer
Seamless construction for applicable sizes, materials and wall thicknesses.
Welded Eccentric Reducer
Welded construction for selected sizes and materials where permitted by the applicable specification.
Fabricated Eccentric Reducer
Custom-fabricated reducers for large diameters, heavy wall thicknesses and special configurations.
Standard Eccentric Reducer dimensions are manufactured in accordance with ASME B16.9, where applicable.
Available wall thicknesses include:
SCH 5S, 10S, 20, 40S, STD, 80S, XS, 100, 120, 140, 160 and XXS, together with project-specific wall thicknesses.
Ordering dimensions should identify both the large-end size and small-end size, for example:
The required orientation should also be identified:
FSU — Flat Side Up
FSD — Flat Side Down
For large-diameter, heavy-wall or fabricated reducers, dimensions can be manufactured according to approved engineering drawings.
Elite Eccentric Reducers are manufactured using suitable forming, welding and fabrication processes according to material, size and project requirements.
Quality control can include:
Elite can manufacture Eccentric Reducers according to customer drawings, piping isometrics and project specifications, including:
Depending on project requirements, supply can include:
Elite Buttweld Eccentric Reducers are used in:
Eccentric Reducers are particularly useful where pipe elevation, drainage, pump suction arrangement or prevention of unwanted liquid/air pockets must be considered in the piping design.
When ordering Buttweld Eccentric Reducers, please specify:
| Item | Required Information |
| Product | Buttweld Eccentric Reducer |
| Large End Size | NPS |
| Small End Size | NPS |
| Orientation | FSU / FSD |
| Material & Grade | ASTM / ASME specified grade |
| Wall Thickness | Schedule or actual thickness |
| Construction | Seamless / Welded / Fabricated |
| Standard | ASME B16.9 or project specified |
| Reducer Length | Standard / Project Specified |
| End Preparation | ASME B16.25 or project specified |
| Surface Finish | Standard / Pickled / Blasted / Polished / Coated |
| Inspection | PMI / UT / RT / MT / PT / Hardness etc. |
| Documentation | EN 10204 3.1 / 3.2 and project documents |
| Quantity | Required quantity |
| Special Requirements | Drawing, coating, NACE, testing or other project requirements |
Typical Order Example:
6″ × 4″ Eccentric Reducer, ASME B16.9, ASTM A234 WPB, SCH 40, FSU, Seamless, ASME B16.25 Bevel Ends, EN 10204 3.1, PMI
