SS 904L ReducerASTM A403 · ASME B16.9 · Manufacturer, trader & exporter, India
Alloy 904L · UNS N08904
An SS 904L reducer is a fitting that joins two pipes of different sizes, made from SS 904L to ASTM A403 WP904L. Concentric reducers keep the centreline in line and suit vertical lines. Eccentric reducers keep one side flat — flat on top at pump suctions to avoid air pockets, flat on the bottom in pipe racks.
For the full 904L fittings range, see SS 904L pipe fittings.
- ASTM A403
- ASME B16.9
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 904L Reducer?
- What it is
- A fitting that joins two pipes of different sizes
- Material
- ASTM A403 WP904L
- Dimensions
- ASME B16.9 · MSS SP-43
- Grade
- SS 904L · UNS N08904
- Best at
- Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water
SS 904L Reducer Specification
| Product | SS 904L Reducer |
|---|---|
| Material standard | ASTM A403 WP904L |
| Dimensional standard | ASME B16.9 · MSS SP-43 |
| Sizes | ½" – 48" |
| Wall / class | Sch 5S – XXS, to match pipe |
| Ends | Bevelled to ASME B16.25 |
| Testing | PMI (as specified in the PO) · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 or 3.2 on request / as specified in the PO |
When to Choose a Reducer
Concentric reducers keep the centreline in line and suit vertical lines. Eccentric reducers keep one side flat — flat on top at pump suctions to avoid air pockets, flat on the bottom in pipe racks.
- Concentric and eccentric
- Flat-top on pump suction
- Seamless or welded
More on choosing: Reducer guide.
SS 904L Reducer: Why 904L for reducers
Concentric reducers keep the centreline in line and suit vertical lines. Eccentric reducers keep one side flat — flat on top at pump suctions to avoid air pockets, flat on the bottom in pipe racks. In SS 904L, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Stainless fittings keep the line clean and corrosion-free. SS 904L is picked for dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water. |
|---|---|
| Typical service | Sulphuric acid plants — Coolers, piping and tanks for dilute sulphuric acid. |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER385 (AWS A5.9) |
SS 904L Reducer Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Nickel | As specified |
| Chromium | As specified |
| Molybdenum | As specified |
| Copper | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Nitrogen | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS N08904.
SS 904L Reducer Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS N08904 — Annealed plate & sheet.
Full chemistry, properties and equivalents are on the SS 904L grade page.
Other SS 904L pipe fittings
SS 904L Reducer dimensions — ASME B16.9
Values in mm, the same for every material; the wall thickness matches the pipe schedule.
| NPS | OD | Reducer length H |
|---|---|---|
| ½" | 21.3 | — |
| ¾" | 26.7 | 38 |
| 1" | 33.4 | 51 |
| 1½" | 48.3 | 64 |
| 2" | 60.3 | 76 |
| 3" | 88.9 | 89 |
| 4" | 114.3 | 102 |
| 6" | 168.3 | 140 |
| 8" | 219.1 | 152 |
| 10" | 273.1 | 178 |
| 12" | 323.9 | 203 |
| 16" | 406.4 | 356 |
| 20" | 508.0 | 508 |
| 24" | 610.0 | 508 |
Full chart: ASME B16.9 fitting dimensions.
SS 904L Reducer — questions buyers ask
Why use an eccentric reducer at a pump suction?
Installed flat side up, it prevents air pockets that can cause cavitation.
Can SS 904L reducers be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
Which standard covers SS 904L reducers?
The material is ASTM A403 WP904L; dimensions follow ASME B16.9 · MSS SP-43. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 904L reducer?
The alloy price, the size and schedule or class, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 or 3.2 certificates available on request / as specified in the PO; dimensional reports as required. PMI can be arranged depending on product and requirements, as specified in the PO.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026