ASTM A403 Stainless Steel Buttweld Reducer Fittings — Concentric & Eccentric Types
Amardeep Steel is a Mumbai-based manufacturer, supplier, and exporter of SS reducer fittings, stainless steel concentric and eccentric reducers conforming to ASME/ANSI B16.9 and ASTM A403. Our stainless steel pipe reducer range covers seamless sizes 1/2" to 24" and fabricated sizes up to 48", with schedules from Sch 5 to XXS. Available in SS 304, 304L, 316, 316L, Duplex, Super Duplex and Nickel Alloy grades, these fittings serve oil & gas, petrochemical, power, and shipbuilding applications worldwide.
Amardeep Steel has supplied ASTM A403 SS reducer fittings to 50+ countries. All products are supplied with Mill Test Certificates (MTC EN 10204/3.1) and are available in EIL-approved grades. Part of our complete SS Buttweld Fittings range alongside SS Elbows and other fitting types.
Request pricing and full dimension charts for any grade or size.
Concentric vs Eccentric Reducer — Key Differences
Both reducer types serve different piping geometries and flow conditions. Choosing the right type prevents operational issues including cavitation, air locking, and solids settling.
|
Property |
Stainless Steel Concentric Reducer |
Stainless Steel Eccentric Reducer |
|---|---|---|
|
Shape / Geometry |
Symmetrical cone — both ends on same centreline |
Asymmetric — one side flat, centrelines offset |
|
Typical Application |
Vertical pipelines, gas/steam lines, in-line assemblies |
Horizontal liquid lines, pump inlet/suction piping |
|
Drainage |
May retain fluid at low point — not suitable for drain points |
Flat side down allows gravity drainage — no pooling |
|
Air Pocket Risk |
Can trap air in liquid lines if used horizontally |
Prevents air pockets — critical for pump suction |
|
Solids Settling |
Not recommended for slurry / horizontal service |
Prevents solids settling in horizontal slurry lines |
|
Installation Alignment |
Easier to centre — suitable for inline assemblies |
Available BOP (Bottom Flat) and TOP (Top Flat) orientation |
|
Common Systems |
HVAC, compressed air, steam, gas distribution |
Oil & gas, process liquid, pump suction, slurry |
|
Best For |
Vertical lines | Gas / Steam | HVAC |
Pump suction | Horizontal liquid lines | Slurry |
Stainless Steel Concentric Reducer
A stainless steel concentric reducer is a symmetrical, cone-shaped fitting used to join pipe sections of different diameters on the same centreline. Because both ends are perfectly aligned, it creates a uniform and symmetrical flow profile, making it the ideal choice for gas lines, steam lines, and compressed air distribution. These fittings are most commonly utilized in vertical piping configurations where gravity helps maintain flow uniformity without the risk of pooling. Additionally, their symmetrical design makes them significantly easier to align during installation, ensuring a precise fit for complex inline assemblies.
Stainless Steel Eccentric Reducer
A stainless steel eccentric reducer features an offset geometry where one side remains completely flat, allowing it to keep either the top or the bottom of the pipe level. This design is critical for horizontal liquid lines and pump suction piping, as it effectively prevents the formation of air pockets that lead to pump cavitation. Available in both Bottom of Pipe (BOP) and Top of Pipe (TOP) configurations, these reducers are essential for systems transporting slurries or process liquids, as the flat side facilitates proper drainage and prevents the settling of solids. By maintaining a constant flow line on one side, eccentric reducers ensure the mechanical integrity and efficiency of high-performance pumping systems.
Specification of SS Reducer Fittings
All Amardeep Steel buttweld reducers are manufactured to international standards with full MTC documentation.
|
Parameter |
Detail |
|---|---|
|
Material Standard |
ASTM A403 / ASME SA403 |
|
Dimensional Standard |
ASME B16.9 / B16.25 / B16.28 |
|
DIN Standard |
DIN 2605, 2615, 2616, 2617, 28011 |
|
MSS Standard |
MSS SP-43 |
|
Size Range |
1/2" – 48" (DN15 – DN1200) |
|
Wall Thickness / Schedule |
Sch 5S, 10S, 20, 30, 40S, 60, 80S, XS, 120, 140, 160, XXS |
|
Form |
Seamless & Welded / Fabricated |
|
End Type |
Bevelled Ends (Buttweld) — Plain Bevel, Compound Bevel |
|
MTC Certificate |
EN 10204 / 3.1 (3.2 on request) |
|
Pressure Class |
Class 150 (150 PSI, −20°F to 500°F) to Class 900 (900 PSI, −20°F to 1000°F) |
|
Surface Finish |
Pickled, Polished (as required) |
|
Testing |
PMI, Hardness, Ultrasonic, HIC — per applicable standard |
|
Third-Party Inspection |
Available on request (SGS, BV, TUV, Lloyds) |
Available Grades for SS Reducer Fittings
We stock and manufacture buttweld reducers across the complete range of austenitic stainless steel grades.
SS Reducer Grades per ASTM A403
|
Grade |
ASTM A403 Designation |
UNS No. |
DIN / Werkstoff |
Key Property / Application |
|---|---|---|---|---|
|
SS 304 |
ASTM A403 WP304 |
S30400 |
1.4301 |
General-purpose corrosion resistance; food, chemical industries |
|
SS 304L |
ASTM A403 WP304L |
S30403 |
1.4306 / 1.4307 |
Low carbon for post-weld service; pharma, dairy, food processing |
|
SS 316 |
ASTM A403 WP316 |
S31600 |
1.4401 |
2–3% Mo for pitting resistance; marine, chemical processing |
|
SS 316L |
ASTM A403 WP316L |
S31603 |
1.4404 |
Most popular for process piping; chloride environments, offshore |
|
SS 321 |
ASTM A403 WP321 |
S32100 |
1.4541 |
Ti-stabilised; high-temp service up to 900°C |
|
SS 347 |
ASTM A403 WP347 |
S34700 |
1.4550 |
Nb-stabilised; nuclear, petrochemical high-temp service |
|
SS 904L |
ASTM A403 WP904L |
N08904 |
1.4539 |
Super-austenitic; sulfuric acid, FGD, seawater desalination |
|
SS 317L |
ASTM A403 WP317L |
S31703 |
1.4438 |
Higher Mo than 316L; pulp & paper, sulfuric acid environments |
Chemical Composition of Key SS Grades
|
Grade |
C% (max) |
Cr% |
Ni% |
Mo% |
Mn% (max) |
Si% (max) |
S% (max) |
|---|---|---|---|---|---|---|---|
|
SS 304 |
0.08 |
18.00–20.00 |
8.00–10.50 |
— |
2.00 |
0.75 |
0.03 |
|
SS 304L |
0.03 |
18.00–20.00 |
8.00–12.00 |
— |
2.00 |
0.75 |
0.03 |
|
SS 316 |
0.08 |
16.00–18.00 |
10.00–14.00 |
2.00–3.00 |
2.00 |
0.75 |
0.03 |
|
SS 316L |
0.03 |
16.00–18.00 |
10.00–14.00 |
2.00–3.00 |
2.00 |
0.75 |
0.03 |
|
SS 321 |
0.08 |
17.00–19.00 |
9.00–12.00 |
— |
2.00 |
1.00 |
0.03 |
|
SS 347 |
0.08 |
17.00–19.00 |
9.00–13.00 |
— |
2.00 |
1.00 |
0.03 |
|
SS 904L |
0.02 |
19.00–23.00 |
24.00–26.00 |
4.00–5.00 |
2.00 |
1.00 |
0.03 |
SS Reducer Dimensions — ASME B16.9
|
Nominal Size (Large End) |
OD Large End (mm) |
OD Small End (mm) |
Length H (mm) |
Sch 10S WT (mm) |
Sch 40S WT (mm) |
|---|---|---|---|---|---|
|
1/2" × 3/8" |
21.3 |
17.2 |
38 |
1.65 |
2.77 |
|
1" × 3/4" |
33.4 |
26.7 |
51 |
2.77 |
3.38 |
|
2" × 1-1/2" |
60.3 |
48.3 |
76 |
2.77 |
3.91 |
|
3" × 2" |
88.9 |
60.3 |
89 |
3.05 |
5.49 |
|
4" × 3" |
114.3 |
88.9 |
102 |
3.05 |
6.02 |
|
6" × 4" |
168.3 |
114.3 |
140 |
3.40 |
7.11 |
|
8" × 6" |
219.1 |
168.3 |
152 |
3.76 |
8.18 |
|
10" × 8" |
273.1 |
219.1 |
165 |
4.19 |
9.27 |
|
12" × 10" |
323.9 |
273.1 |
178 |
4.57 |
9.53 |
* Full dimension tables including non-standard reductions, heavy wall, and XXS available on request.
Stainless Steel Reducer Fittings Weight Chart
|
NPS |
Concentric Reducer Weight (kg) |
Eccentric Reducer Weight (kg) |
|---|---|---|
|
1-1/2" |
0.34 |
0.28 |
|
2" |
1.08 |
0.41 |
|
2-1/2" |
1.81 |
0.68 |
|
3" |
2.27 |
0.82 |
|
4" |
4.08 |
1.53 |
|
5" |
7.26 |
2.72 |
|
6" |
6.31 |
3.86 |
|
8" |
10.7 |
5.99 |
|
10" |
16.3 |
9.98 |
|
12" |
32.1 |
15.4 |
Weights are indicative for standard wall (Sch 40S / STD). Actual weight varies by schedule and grade. Full weight tables on request.
Industry Applications for SS Reducer Fittings
Our buttweld reducers are supplied globally to critical process industries. Stainless steel concentric and eccentric reducers serve applications where corrosion resistance, pressure integrity, and dimensional accuracy are non-negotiable.
- Oil & Gas Refineries
- Petrochemical Plants
- Power Generation
- Pharmaceutical Manufacturing
- Food & Beverage Processing
- Desalination Plants
- Chemical Processing
- Marine Engineering
- Pulp & Paper Mills
- Pump & Valve Manufacturing
- FGD Systems (Flue Gas)
- Heat Exchangers
Packaging, Payment & Delivery — SS Reducer Fittings
Packaging
- SS reducer fittings are wrapped in plastic/bubble wrap per piece
- Bundled by size in wooden crates or cartons for export
- End protection caps fitted to bevelled ends to prevent damage in transit
Payment Terms
- LC (Letter of Credit)
- TT (Telegraphic Transfer / Wire Transfer)
- Advance payment / as agreed
Request SS Reducer Dimensions & Price List
Share your size range, grade, and quantity. We will respond with pricing, stock availability, and dimensions within 4 hours. We supply ASTM A403 SS concentric and eccentric reducers globally. Sizes 1/2"-48", all schedules, all grades. Mill test certificates provided.
Frequently Asked Questions — SS Reducer Fittings
What is the difference between a stainless steel concentric and eccentric reducer?
A stainless steel concentric reducer has both pipe ends on the same centreline, forming a symmetrical cone. It is used in vertical pipelines, gas lines, and steam lines. A stainless steel eccentric reducer has one flat side — keeping the bottom (or top) of the pipe level — which is critical for pump suction piping (to prevent cavitation) and horizontal liquid lines (to prevent air pockets and solids settling).
What standard governs stainless steel buttweld reducer fittings?
Stainless steel buttweld reducer fittings are manufactured to ASTM A403 / ASME SA403 (material standard) and dimensioned to ASME/ANSI B16.9 (dimensional standard). Additional standards include ASME B16.25 (butt-welding ends), ASME B16.28 (short radius), MSS SP-43, and DIN 2605/2615/2616/2617.
What is the difference between seamless and welded SS reducers?
Seamless SS reducers are manufactured from a single piece of material with no weld seam — offering higher pressure ratings and uniformity. Available up to 24" NB. Welded and fabricated reducers are made from rolled and welded plate or pipe — available up to 48" NB and used where larger diameters are required. Both types are available to ASME B16.9.
Do you supply reducers with third-party inspection certificates?
Yes. All SS reducer fittings are supplied with Mill Test Certificates (MTC) as per EN 10204/3.1. Third-party inspection (TPI) by agencies including SGS, Bureau Veritas, TUV, and Lloyds is available on request. 3.2 certificates are also available for critical applications.
What is the maximum size available for SS concentric reducers?
Seamless SS concentric reducers are available up to 24" NB. Welded and fabricated concentric reducers are available up to 48" NB (DN1200), covering all standard schedule walls from Sch 5S through XXS.
What is the HSN code for stainless steel reducer fittings?
The HSN code for stainless steel reducer fittings is 73072900.
What grades are available for high-temperature SS reducer fittings?
For high-temperature service, SS 321 (Ti-stabilised, up to 900°C) and SS 347 (Nb-stabilised) are the recommended grades. For very high temperatures in power generation, creep-resistant grades are available on request.
