Buttweld Concentric Reducer Manufacturer, Supplier & Exporter
A buttweld concentric reducer joins two pipes of different sizes on a common centreline, with a symmetrical cone between the large and small ends. Raaj Fittings manufactures and exports concentric reducers to ASME B16.9 in stainless steel, duplex and super duplex, nickel alloys, carbon steel and alloy steel, in seamless and welded construction.
Because both ends share the same axis, a concentric reducer keeps the pipe centreline straight. It is the standard reducer for vertical lines, for pump discharges and for horizontal lines where trapping liquid or gas is not a concern, and it gives a smooth, gradual change of velocity with little turbulence.
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 concentric 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.
Concentric Reducer Specifications
Large ends ¾" NPS to 48" NPS and larger; reductions as tabulated in ASME B16.9
Large end × small end, e.g. 6" × 4"
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 (formed from pipe) and welded (from plate or welded pipe)
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 concentric reducers in the following materials and grades. All grades are supplied with EN 10204 3.1 / 3.2 Mill Test Certificates.
Stainless Steel Concentric 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 Concentric 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 Concentric 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 Concentric 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 Concentric 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
When to Use a Concentric Reducer
A concentric reducer changes the pipe size while keeping both ends on the same centreline. Its length is fixed by ASME B16.9 for each large-end size — for example 102 mm for a 4" reducer — whatever the small-end size, so layouts are easy to plan.
- Vertical lines — the symmetrical shape suits risers and down-comers.
- Pump discharges — the normal reducer between a pump outlet and a larger line.
- Gas and steam lines — where there is no risk of trapping condensate in a horizontal run.
- Smooth flow — a gradual cone gives low turbulence and pressure loss.
Concentric or Eccentric?
In a horizontal line, a concentric reducer leaves a step at the top and bottom of the pipe. On pump suctions this can trap air or vapour, and on drain lines it can hold liquid. In those cases an eccentric reducer, with one flat side, is used instead. On pipe racks, eccentric reducers are also used to keep the bottom of the pipe level on its supports.
Reducers in Branch Connections
Where a smaller branch leaves a header, a reducing tee usually replaces an equal tee followed by a reducer, saving one fitting and one weld. To close a line rather than reduce it, use a pipe end cap.
Applications & Industries
- Pump and compressor discharge piping
- Vertical risers and down-comers in process plants
- Steam, gas and air distribution lines
- Control valve and meter runs where line size changes
- Offshore and seawater systems in duplex and super duplex
- Water transmission and treatment pipelines
Explore the full range of buttweld fittings.
Testing, Inspection, Marking & Packing
Concentric 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, both outside diameters, concentricity, 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 Concentric 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 — Concentric 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.
Concentric Reducers — FAQs
A concentric reducer is a cone-shaped buttweld fitting that joins two pipes of different sizes with both ends on the same centreline.
They are used in vertical lines, on pump discharges and in gas, steam and air lines where the change in pipe size does not risk trapping liquid or gas.
A concentric reducer keeps both ends on one centreline. An eccentric reducer has one flat side, so the centrelines are offset; it is used on horizontal lines to avoid trapping air or liquid.
ASME B16.9 sets the length by the large-end size — for example 102 mm (4") for a 4" reducer — regardless of the small-end size.
Give the large end × small end, the schedule at each end, the material grade and construction — for example 6" × 4" SCH 40 × SCH 40, ASTM A403 WP316L, seamless.
Yes. We supply concentric 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.
