ASTM A335 P11 Orifice FlangeASTM A182 · ASME B16.36 · Manufacturer, stockist & exporter, India
SA-335 P11 · 1¼Cr-½Mo alloy pipe · ORF
An ASTM A335 P11 orifice flange is a pair of weld neck or slip-on flanges with pressure taps that hold an orifice plate, for use with ASTM A335 P11 pipe. ASTM A335 P11 itself is a pipe or plate specification, so the matching orifice flange is made to ASTM A182 F11 — which is what we supply for P11 lines. Orifice flanges are used for flow measurement. Each flange has two ½" NPT pressure-tap holes, and jack screws help separate the pair to change the plate.
- ASTM A182
- ASME B16.36
- 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 Orifice Flange?
- What it is
- A pair of weld neck or slip-on flanges with pressure taps that hold an orifice plate
- Material
- ASTM A182 F11
- Dimensions
- ASME B16.36
- Grade
- ASTM A335 P11
- Best at
- Steam and hot-oil piping up to about 550 °C
ASTM A335 P11 Orifice Flange Specification
| Product | ASTM A335 P11 Orifice Flange |
|---|---|
| Material standard | ASTM A182 F11 |
| Dimensional standard | ASME B16.36 |
| Sizes | 1" – 24" (ASME B16.36) |
| Pressure class | Class 300 – 2500 |
| Facing | RF · FF · RTJ · tongue & groove |
| Bore | To match pipe schedule (state on order) |
| Testing | Chemical & mechanical per heat · NDT · impact where specified |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
When to Choose an Orifice Flange
Orifice flanges are used for flow measurement. Each flange has two ½" NPT pressure-tap holes, and jack screws help separate the pair to change the plate.
- Class 300 minimum per ASME B16.36
- Supplied in pairs with jack screws
- Pressure taps: ½" NPT, two per flange
More on choosing: Orifice flange guide.
ASTM A335 P11 Orifice Flange: Why P11 for orifice flanges
Orifice flanges are used for flow measurement. Each flange has two ½" NPT pressure-tap holes, and jack screws help separate the pair to change the plate. 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 flanges carry most utility, hydrocarbon and high-temperature service. 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. |
| B16.5 material group | 1.9 — Group 1.9 applies to A182 F11 Class 2. Chrome-moly welds usually need PWHT; the code sets thickness exemptions. |
| Bolting | ASTM A193 B7 studs with A194 2H nuts; B16 with Gr 4 or 7 nuts where the temperature calls for it |
| 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 Orifice Flange Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 1.00 – 1.50 |
| Molybdenum | 0.44 – 0.65 |
| Carbon | 0.05 – 0.15 |
| Manganese | 0.30 – 0.60 |
| Silicon | 0.50 – 1.00 |
| Phosphorus | 0.025 max |
| Sulphur | 0.025 max |
ASTM A335 P11 Orifice Flange Mechanical Properties
| Minimum values | Value |
|---|---|
| Tensile strength | 415 MPa · 60 ksi |
| Yield strength 0.2% | 205 MPa · 30 ksi |
| Elongation | 30% |
Full chemistry, properties and equivalents are on the ASTM A335 P11 grade page.
Other ASTM A335 P11 flanges
ASTM A335 P11 Orifice Flanges for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiASTM A335 P11 Orifice Flange — questions buyers ask
Why is the minimum class 300 for orifice flanges?
ASME B16.36 starts at Class 300 so the flange is thick enough to drill the pressure taps radially.
What pressure rating does a ASTM A335 P11 orifice flange have?
It depends on class and temperature. ASTM A335 P11 forgings are in ASME B16.5 material group 1.9; read your class column in that group's table at the design temperature.
Can ASTM A335 P11 orifice flanges 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 orifice flanges?
The material is ASTM A182 F11; dimensions follow ASME B16.36. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a ASTM A335 P11 orifice flange?
The steel price, the size and pressure 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 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026