ASTM A335 P11 ReducerASTM A234 · ASME B16.9 · Manufacturer, trader & exporter, India
SA-335 P11 · 1¼Cr-½Mo alloy pipe
An ASTM A335 P11 reducer is a fitting that joins two pipes of different sizes, for use with ASTM A335 P11 pipe. ASTM A335 P11 itself is a pipe or plate specification, so the matching reducer is made to ASTM A234 WP11 — which is what we supply for P11 lines. 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.
- ASTM A234
- 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 ASTM A335 P11 Reducer?
- What it is
- A fitting that joins two pipes of different sizes
- Material
- ASTM A234 WP11
- Dimensions
- ASME B16.9 · MSS SP-43
- Grade
- ASTM A335 P11
- Best at
- Steam and hot-oil piping up to about 550 °C
ASTM A335 P11 Reducer Specification
| Product | ASTM A335 P11 Reducer |
|---|---|
| Material standard | ASTM A234 WP11 |
| 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 | Chemical & mechanical per heat · NDT · impact where specified |
| 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.
ASTM A335 P11 Reducer: Why P11 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 ASTM A335 P11, 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 | Carbon and low-alloy fittings suit hydrocarbon, steam and utility lines. ASTM A335 P11 is picked for steam and hot-oil piping up to about 550 °C. |
|---|---|
| Typical service | Power plants — Main steam and reheat lines. |
| Welding to carbon steel | Matching carbon or low-alloy filler is used; joints to stainless need ER309L |
| Matching filler | ER80S-B2 / E8018-B2 |
ASTM A335 P11 Reducer Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Molybdenum | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A335 Grade P11.
ASTM A335 P11 Reducer Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | 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 A335 Grade P11 — condition per order.
Full chemistry, properties and equivalents are on the ASTM A335 P11 grade page.
Other ASTM A335 P11 pipe fittings
ASTM A335 P11 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.
ASTM A335 P11 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 ASTM A335 P11 reducers be welded to carbon steel?
Yes — matching carbon or low-alloy filler is used; joints to stainless need ER309L.
Which standard covers ASTM A335 P11 reducers?
The material is ASTM A234 WP11; 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 ASTM A335 P11 reducer?
The steel 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