Tubewell Steel & Engg. Co. is a leading manufacturer and stockist specializing in Alloy Steel Pipes, Tubes, Fittings and Flanges for critical industrial applications.
1.25% Chromium – 0.5% Molybdenum seamless alloy steel pipes for high-temperature steam, boiler and refinery service.
Tubewell Steel & Engg. Co. manufactures and stocks ASTM A335 P11 pipes – a 1¼Cr-½Mo ferritic alloy steel built for elevated-temperature service. P11 offers good creep strength, oxidation resistance and weldability, making it a dependable choice for steam lines, headers and refinery heaters.
What makes A335 P11 the go-to grade for moderate-temperature service
ASTM A335 P11 is a seamless ferritic alloy steel pipe containing nominally 1.25% chromium and 0.5% molybdenum. Chromium improves resistance to oxidation and sulphidation, while molybdenum raises creep and rupture strength at temperatures up to about 595°C (1100°F). The grade is supplied in the normalized and tempered or annealed condition, which gives a stable, fine-grained microstructure.
We supply P11 pipes in hot-finished and cold-drawn forms, plain or bevelled ends, with complete traceability from heat number to dispatch. Every lot is backed by mill test certificates per EN 10204 3.1, and third-party inspection (TPI) by agencies such as BV, TÜV, SGS or Lloyd's can be arranged on request.
Standard supply range for ASTM A335 P11 pipes
| Parameter | Details |
|---|---|
| Standard | ASTM A335, ASME SA335 |
| Grade | P11 (UNS K11597) |
| Type | Seamless – Hot Finished / Cold Drawn |
| Size (NB) | 1/2" NB to 24" NB |
| Outer Diameter | 21.3 mm to 610 mm |
| Wall Thickness | SCH 10, 20, 40, STD, 60, 80, XS, 100, 120, 140, 160, XXS |
| Length | Single Random, Double Random, Cut Length (up to 12 m) |
| Ends | Plain End, Bevelled End, Threaded |
| Heat Treatment | Full / Isothermal Annealed or Normalized & Tempered (min. 650°C) |
| Surface | Black Painted, Varnished, Anti-rust Oil, Pickled |
| Dimension Standard | ASME B36.10M |
| Testing | Hydrostatic, Ultrasonic, Eddy Current, Flattening, Flaring, Hardness, PMI |
| Certificates | EN 10204 3.1 / 3.2, IBR Form III-A, TPI Reports |
International equivalents of A335 P11
| Standard | ASTM | UNS | EN | DIN / W.Nr. | JIS | BS |
|---|---|---|---|---|---|---|
| P11 | A335 P11 | K11597 | 13CrMo4-5 | 1.7335 | STPA 23 | 3604 HFS 621 |
Weight %, as per ASTM A335
| Grade | C | Mn | P | S | Si | Cr | Mo |
|---|---|---|---|---|---|---|---|
| A335 P11 | 0.05 – 0.15 | 0.30 – 0.60 | 0.025 max | 0.025 max | 0.50 – 1.00 | 1.00 – 1.50 | 0.44 – 0.65 |
Minimum values at room temperature
| Grade | Tensile Strength | Yield Strength (0.2%) | Elongation (Long.) | Elongation (Trans.) |
|---|---|---|---|---|
| A335 P11 | 415 MPa (60 ksi) min | 205 MPa (30 ksi) min | 30% min | 20% min |
Typical values (for reference)
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.75 g/cm³ | 0.280 lb/in³ |
| Melting Range | 1450 – 1510 °C | 2640 – 2750 °F |
| Modulus of Elasticity | 205 GPa | 29.7 × 10³ ksi |
| Thermal Conductivity (100°C) | 37 W/m·K | 21.4 BTU/h·ft·°F |
| Mean Thermal Expansion (20–300°C) | 12.4 µm/m·°C | 6.9 µin/in·°F |
| Specific Heat | 0.46 J/g·°C | 0.11 BTU/lb·°F |
| Max. Service Temperature | ≈ 595 °C | ≈ 1100 °F |
As per ASME B36.10M – wall thickness (mm) / weight (kg/m)
| NPS | OD (mm) | SCH 40 WT | SCH 40 Wt | SCH 80 WT | SCH 80 Wt | SCH 160 WT | SCH 160 Wt |
|---|---|---|---|---|---|---|---|
| 1/2" | 21.3 | 2.77 | 1.27 | 3.73 | 1.62 | 4.78 | 1.95 |
| 3/4" | 26.7 | 2.87 | 1.69 | 3.91 | 2.20 | 5.56 | 2.90 |
| 1" | 33.4 | 3.38 | 2.50 | 4.55 | 3.24 | 6.35 | 4.24 |
| 1 1/4" | 42.2 | 3.56 | 3.39 | 4.85 | 4.47 | 6.35 | 5.61 |
| 1 1/2" | 48.3 | 3.68 | 4.05 | 5.08 | 5.41 | 7.14 | 7.25 |
| 2" | 60.3 | 3.91 | 5.44 | 5.54 | 7.48 | 8.74 | 11.11 |
| 2 1/2" | 73.0 | 5.16 | 8.63 | 7.01 | 11.41 | 9.53 | 14.92 |
| 3" | 88.9 | 5.49 | 11.29 | 7.62 | 15.27 | 11.13 | 21.35 |
| 4" | 114.3 | 6.02 | 16.07 | 8.56 | 22.32 | 13.49 | 33.54 |
| 6" | 168.3 | 7.11 | 28.26 | 10.97 | 42.56 | 18.26 | 67.56 |
| 8" | 219.1 | 8.18 | 42.55 | 12.70 | 64.64 | 23.01 | 111.27 |
| 10" | 273.1 | 9.27 | 60.29 | 15.09 | 95.98 | 28.58 | 172.33 |
| 12" | 323.9 | 10.31 | 79.71 | 17.48 | 132.05 | 33.32 | 238.76 |
WT = Wall Thickness in mm, Wt = Weight in kg/m. Values are nominal; actual weights may vary within ASTM tolerances.
Where ASTM A335 P11 pipes are used
Main steam, hot reheat lines and boiler headers in thermal power stations.
Heater tubes, hydro-treaters and high-temperature process piping.
Cracker units and reformers handling hydrogen at elevated temperature.
Superheater and reheater piping exposed to sustained heat and pressure.
Shell-side and high-temperature connection piping in exchangers.
Ammonia and urea plant lines needing hydrogen-attack resistance.
Quality you can verify on every heat
Large inventory for fast dispatch
MTC EN 10204 3.1 / 3.2
Positive material identification
Pan-India & export shipping
Quick answers about A335 P11 pipes
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