Steel A369 FP11
ASTM A369 FP11
A369 FP11 is a forged and bored 1.25Cr-0.5Mo-Si alloy pipe, the forged equivalent of seamless A335 P11 and of 13CrMo4-5 / 1.7335.
Reference datasheet — A369 FP11 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the N+T condition
A369 FP11 tempers and conditions
A369 FP11 is supplied in 3 conditions, soft to hard. N+T is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest permitted condition; choose when maximum machinability, cold bending or lowest residual stress is wanted and only minimum spec strength is required. | 285 | 470 | 32 | 140 HB | 8 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for FP11 forged/bored pipe used in creep-range steam and hydrogen service; best balance of strength, toughness and code allowables. | 330 | 510 | 28 | 155 HB | — |
Quenched and tempered | Occasionally supplied for thick forged sections or valve/fitting bodies where higher yield and uniform bainitic structure are specified; still tempered high to stay code-compliant. | 400 | 560 | 24 | 12 HRC | 7.6 % IACS |
Supply forms, finishes and certifications
Ways A369 FP11 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
ISO-A | Isothermally annealed | Certification |
What is A369 FP11?
A369 FP11 is a forged and bored 1.25Cr-0.5Mo-Si alloy pipe, the forged equivalent of seamless A335 P11 and of 13CrMo4-5 / 1.7335. It is specified for elevated-temperature power and refinery piping and is supplied normalized and tempered, annealed, ISO-annealed or quenched and tempered; the default N+T condition gives 330 MPa yield, 510 MPa tensile, 28 % elongation, about 155 HB and service to 565 °C. Weldability is moderate (score 60), with 150–200 °C preheat and 700–760 °C PWHT normally mandatory, and the steel is not corrosion resistant. A369 FP1 is the lower-cost choice below 470 °C. A369 FP11 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,490°C (2,714 °F). A369 FP11 has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 78% of steel grades. Elongation at break is 28% and the elastic modulus is 207 GPa (30 Msi).
What is A369 FP11 used for?
- Power plant steam piping
- Refinery high-temperature piping
- Superheater outlet headers
- Hydrogen-service transfer lines
- Catalytic reformer piping
- Forged pipe spools and thick-wall elbows
- Turbine bypass piping
Advantages
- High service temperature — 565°C (1,049 °F), better than 96% of steel grades
- Ductile — tolerates forming and impact — 28%, better than 89% of steel grades
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
Limitations
- Low strength — 330 MPa (47.9 ksi), worse than 78% of steel grades
A369 FP11 properties
Typical room-temperature values for A369 FP11-N+T; bars are the position among steel grades.
Physical3
A369 FP11 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical15
A369 FP11 has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 78% of steel grades. Elongation at break is 28% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A369 FP11 is rated for continuous service to 565°C (1,049 °F). It conducts heat at 39 W/m·K (22.5 BTU/hr·ft·°F), worse than 67% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical2
A369 FP11 has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of A369 FP11 takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability6
A369 FP11's machinability is good (58/100, better than 75% of steel grades); weldability good (60/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. A369 FP11 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A369 FP11
Is A369 FP11 easy to machine?
Machines like a medium-carbon low-alloy steel at ~60 % of 1212 — use rigid setups, carbide inserts and moderate speeds; the high Si content makes it slightly gummy and abrasive on tool edges.
Can A369 FP11 be welded?
Weldable by GTAW root / SMAW-FCAW fill with matching B2/1.25Cr-0.5Mo filler; preheat 150–200 °C, interpass ≤ 300 °C and PWHT 700–760 °C are normally mandatory to avoid hydrogen cracking and to restore toughness.
Can A369 FP11 be formed, bent or molded?
Hot bend or hot form at 900–1000 °C followed by full re-heat treatment; cold bending is possible on thin walls but should be followed by stress relief.
A369 FP11 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | 0.05 – 0.15 | 0.11 |
| Mn | 0.3 – 0.6 | 0.45 |
| Sideliberately high Si distinguishes P11/FP11 from 13CrMo4-5 min Si | 0.5 – 1 | 0.7 |
| Cr | 1 – 1.5 | 1.25 |
| Mo | 0.44 – 0.65 | 0.55 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on A369 FP11?
Not corrosion-resistant on its own — shot blast then apply high-temperature aluminium/silicone paint or leave under insulation with a coating; polishes to a clean matte finish for NDE and dye-penetrant inspection.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel A369 FP11 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does A369 FP11 cost?
A369 FP11 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
A369 FP11 — frequently asked
What is A369 FP11 used for?
A369 FP11 is typically used for power plant steam piping, refinery high-temperature piping, superheater outlet headers, hydrogen-service transfer lines, catalytic reformer piping and forged pipe spools and thick-wall elbows. In short: 565 °C creep piping grade; forged equivalent of P11; mandatory preheat and PWHT.
What is the yield strength of A369 FP11?
A369 FP11 has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 78% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A369 FP11 easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a medium-carbon low-alloy steel at ~60 % of 1212 — use rigid setups, carbide inserts and moderate speeds; the high Si content makes it slightly gummy and abrasive on tool edges.
Can A369 FP11 be welded?
Yes — weldability is rated good (60/100). Weldable by GTAW root / SMAW-FCAW fill with matching B2/1.25Cr-0.5Mo filler; preheat 150–200 °C, interpass ≤ 300 °C and PWHT 700–760 °C are normally mandatory to avoid hydrogen cracking and to restore toughness.
What surface finishes work on A369 FP11?
Not corrosion-resistant on its own — shot blast then apply high-temperature aluminium/silicone paint or leave under insulation with a coating; polishes to a clean matte finish for NDE and dye-penetrant inspection.
Can A369 FP11 be formed, bent or molded?
Hot bend or hot form at 900–1000 °C followed by full re-heat treatment; cold bending is possible on thin walls but should be followed by stress relief.
What is the maximum service temperature of A369 FP11?
A369 FP11 is rated for continuous use to about 565°C (1,049 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 FP11 N+T and A369 FP11-A?
N+T is the default condition — standard supply condition for FP11 forged/bored pipe used in creep-range steam and hydrogen service; best balance of strength, toughness and code allowables. A: softest permitted condition; choose when maximum machinability, cold bending or lowest residual stress is wanted and only minimum spec strength is required. Yield strength is 330 MPa in N+T versus 285 MPa in A.
How much does A369 FP11 cost?
A369 FP11 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A369/A369M — Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service — ASTM International (2018)
- ASTM A335/A335M — Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service (P11) — ASTM International (2023)
- EN 10216-2 — Seamless steel tubes for pressure purposes, 13CrMo4-5 (1.7335) — CEN (2020)
- ASME BPVC Section II Part D — allowable stresses and physical properties, SA-369 FP11 — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Cr-Mo steels) — ASM International (1990)
- API RP 941 — Steels for Hydrogen Service at Elevated Temperatures — API (2016)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.