Buttweld Eccentric Reducer Manufacturer, Supplier & Exporter
A buttweld eccentric reducer joins two pipes of different sizes with one side of the fitting kept straight, so the centrelines of the two ends are offset. Raaj Fittings manufactures and exports eccentric reducers to ASME B16.9 in stainless steel, duplex and super duplex, nickel alloys, carbon steel and alloy steel, in seamless and welded construction.
The flat side is what makes the eccentric reducer useful in horizontal piping. Installed flat side up, it prevents air or vapour collecting at the top of the line; installed flat side down, it keeps the bottom of the pipe level for drainage and for resting on pipe-rack supports.
Each end is bevelled for butt welding to its own pipe schedule, and every reducer is supplied with EN 10204 3.1 mill test certificates, with 3.2 certification on request.
We export eccentric reducers to EPC contractors, refineries and stockists across the Middle East and GCC, Europe and the Americas — to ASME B16.9 for US and Gulf projects, or EN 10253 / DIN dimensions for European specifications, with PED-compliant supply on request.
Eccentric Reducer Specifications
Large ends ¾" NPS to 48" NPS and larger; reductions as tabulated in ASME B16.9
Large end × small end, e.g. 8" × 6"
SCH 5S to XXS; each end can be bevelled for a different schedule
ASME B16.9, MSS SP-43, MSS SP-75, EN 10253-1 / 10253-2, DIN 2616, JIS B2311 / B2312 / B2313
Seamless and welded
Bevelled ends for butt welding to ASME B16.25
EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request
Materials & Grades
We supply eccentric reducers in the following materials and grades. All grades are supplied with EN 10204 3.1 / 3.2 Mill Test Certificates.
Stainless Steel Eccentric Reducers
Stainless steel buttweld fittings deliver excellent corrosion resistance and are essential in chemical, pharmaceutical, food processing, and marine environments. All grades supplied to ASTM A403 specification.
(ASTM A403 WP304 / WP304L) General corrosion resistance; food, dairy, and chemical service
(ASTM A403 WP316 / WP316L) Enhanced chloride and acid resistance; pharmaceutical, marine, and chemical processing
(ASTM A403 WP316H) Elevated-temperature creep strength for high-temperature process service
(ASTM A403 WP317 / WP317L) Higher molybdenum content; superior corrosion resistance in concentrated acid service
(ASTM A403 WP321) Titanium-stabilised; resists sensitisation at sustained elevated temperatures
(ASTM A403 WP347) Columbium-stabilised; ideal for heat exchangers and high-temperature piping
High-alloy austenitic; superior resistance to hot concentrated sulfuric and phosphoric acids
Duplex & Super Duplex Stainless Steel Eccentric Reducers
Duplex and super duplex grades offer approximately twice the yield strength of standard austenitic stainless steel, combined with excellent resistance to stress corrosion cracking and pitting — ideal for offshore, subsea, and chemical processing environments.
(UNS S31803 / S32205) Offshore topsides, chemical plant, desalination, and seawater piping
(UNS S32750) Seawater systems, subsea equipment, FPSOs, and high-chloride offshore environments
(UNS S32760) High-temperature, high-chloride offshore and subsea service applications
Nickel Alloy Eccentric Reducers
For the most aggressive corrosive environments — concentrated acids, caustic solutions, sour gas service, and extreme temperatures — we offer buttweld fittings in a full range of nickel alloys.
(UNS N06600) High-temperature oxidation and carburisation resistance
(UNS N06625) Outstanding broad-spectrum corrosion resistance; offshore, chemical, and subsea service
(UNS N08825) Resistance to phosphoric and sulfuric acids; FGD systems and chemical plant
(UNS N10276) Universal corrosion resistance across the widest range of aggressive process media
(UNS N06022) Superior resistance to oxidising and reducing acids and pitting attack
(UNS N04400) Suitable for seawater, hydrofluoric acid, and marine and alkali service
(UNS N08020) Engineered for sulfuric acid and aggressive chemical process service
Exceptional corrosion resistance in seawater and oxidising media at low density
(C70600 / C71500) Preferred for marine seawater piping and naval condenser systems
Carbon Steel Eccentric Reducers
Carbon steel is the most widely specified material for general-purpose, hydrocarbon, and elevated-temperature service. The primary grade is ASTM A234 WPB for standard service. For high-yield pipeline fittings, we supply ASTM A860 WPHY grades to MSS SP-75.
Standard carbon steel; primary grade for general-purpose process piping buttweld fittings
Impact-tested carbon steel for low-temperature service down to -46°C (-50°F); LNG and cryogenic piping
High-yield pipeline fittings to MSS SP-75; used in high-pressure oil, gas, and liquid transmission pipelines
Alloy Steel Eccentric Reducers
Chromium-molybdenum alloy steel buttweld fittings are specified for high-temperature, high-pressure service in power generation, petrochemical, and refinery applications. All grades supplied to ASTM A234 specification.
(5% Cr · ½% Mo) Refinery high-temperature service; hydrotreating and catalytic reforming units
(9% Cr · 1% Mo) High-temperature hydrogen-rich process service and steam piping
(1¼% Cr · ½% Mo) Thermal power plant steam, feedwater, and reheat piping
(2¼% Cr · 1% Mo) Reactors and high-temperature pressure piping systems in petrochemical plants
(9% Cr · 1% Mo · V · Nb) Ultra-supercritical steam power plant main steam and hot reheat piping
Flat on Top or Flat on Bottom?
An eccentric reducer can be installed two ways, and the choice depends on what the line carries:
- Flat on top (FOT) — the top of the pipe stays continuous. This is the standard arrangement on pump suction lines, because it leaves no high point where air or vapour can collect and cause cavitation or loss of prime. It is also used in liquid lines that must vent freely.
- Flat on bottom (FOB) — the bottom of the pipe stays continuous. This lets horizontal lines drain completely, prevents liquid pooling in gas or steam lines, and keeps the bottom of pipe at one elevation so it sits evenly on pipe-rack supports.
Always show the required orientation on the piping isometric, as the same fitting serves both purposes.
Eccentric vs Concentric
A concentric reducer keeps both ends on one centreline and is used in vertical lines and on pump discharges. In horizontal lines where trapping air, vapour or liquid matters, the eccentric reducer is the right choice. ASME B16.9 gives both types the same length for a given large-end size — for example 102 mm for a 4" reducer.
Typical Pump Suction Arrangement
On a horizontal end-suction pump, the suction line is often one or two sizes larger than the pump inlet. An eccentric reducer, flat on top, is fitted close to the pump nozzle, usually after a long radius elbow placed far enough upstream to give a steady flow into the pump.
Applications & Industries
- Pump suction lines in refineries, chemical plants and water systems
- Horizontal liquid lines that must drain completely
- Steam and gas lines where condensate must not collect
- Pipe racks where bottom of pipe must be kept level
- Offshore, seawater and fire water systems
- Slurry and process lines where solids must not settle
Explore the full range of buttweld fittings.
Testing, Inspection, Marking & Packing
Eccentric reducers are made under our quality assurance process:
- Incoming material verification with PMI testing
- Chemical and mechanical testing to the applicable ASTM specification
- Heat treatment after forming as required, with pickling and passivation for stainless steels
- Radiographic or ultrasonic examination of weld seams on welded reducers
- Dimensional inspection of length, outside diameters, offset, wall thickness and bevels
- Marking with grade, size, schedules and heat number
Supplied with EN 10204 3.1 mill test certificates; EN 10204 3.2 certificates and third-party inspection are available on request.
Fittings are packed for export with plastic end caps protecting the bevels, rust-preventive or VCI wrapping on carbon and alloy steel, and seaworthy wooden cases; marking, tagging and packing to your specification are available on request.
Why Choose Raaj Fittings for Eccentric Reducers?
Raaj Sagar Steels has supplied piping components since 2003 and today manufactures buttweld fittings at two plants in India for buyers in the Middle East, Europe and the Americas.
- Manufactured in-house — Eccentric reducers are made in our own plants, so material, dimensions and delivery stay under our control.
- Ready stock, short lead times — common sizes and grades are held in stock for prompt dispatch; other sizes, grades and specials are manufactured to order.
- Certified quality — ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certified; PED 2014/68/EU and IBR supply available, and NACE MR0175 / ISO 15156 material on request.
- 100% material verification — PMI testing on incoming material and EN 10204 3.1 mill test certificates with every order; 3.2 certificates on request.
- Third-party inspection ready — we regularly work with SGS, Bureau Veritas, TÜV and DNV.
- Export documentation — MTCs, certificates of origin, packing lists and inspection reports to suit projects in the GCC, Europe and the Americas.
- Export packing — seaworthy packing with end and face protection, and packing to your specification on request.
- Fast response — our team replies to enquiries within one business day.
Eccentric Reducers — FAQs
An eccentric reducer joins two pipe sizes with one side kept straight, so the centrelines of the two ends are offset. It is used in horizontal lines.
Flat side on top. This avoids a high point where air or vapour can collect and enter the pump, which could cause cavitation or loss of prime.
Flat side down keeps the bottom of the pipe continuous, so the line drains fully and sits level on pipe-rack supports. It is common on drain, steam and rack piping.
No. ASME B16.9 gives eccentric and concentric reducers the same end-to-end length for a given large-end size.
Give the large end × small end, both schedules, the material grade and construction, and show the flat-on-top or flat-on-bottom orientation on the isometric drawing.
Yes. We supply eccentric reducers for projects under the European Pressure Equipment Directive (PED 2014/68/EU), and with IBR certification for Indian boiler applications. NACE MR0175 / ISO 15156 compliant material is also available on request for sour service in the Middle East and the Americas.
