Steel A369 FP9
ASTM A369 FP9
A369 FP9 is a 9Cr-1Mo forged and bored alloy steel pipe to ASTM A369, the forged equivalent of A335 P9 seamless pipe.
Reference datasheet — A369 FP9 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 FP9 tempers and conditions
A369 FP9 is supplied in 2 conditions, soft to hard. N+T is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick when maximum softness/machinability and lowest hardness for field bending or heavy machining are needed; slightly lower strength than N+T. | 250 | 450 | 36 | 150 HB | — |
N+TDefault Normalized and tempered | Standard supply condition for FP9 pressure piping: best creep strength and toughness combination for 500–600 °C service. | 300 | 490 | 33 | 170 HB | — |
What is A369 FP9?
A369 FP9 is a 9Cr-1Mo forged and bored alloy steel pipe to ASTM A369, the forged equivalent of A335 P9 seamless pipe. It is used for severe high-temperature, high-pressure process piping to 600 °C, supplied normalized and tempered or annealed with 300 MPa yield, 490 MPa tensile, 33% elongation and 170 HB (87 HRB). The 9Cr chemistry gives the best oxidation and sulfidation resistance in this family but the poorest machinability (45) and weldability (50) scores, with strict preheat, interpass and PWHT requirements. FP5 is the cheaper alternative when conditions are less severe. A369 FP9 has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,450°C (2,642 °F). A369 FP9 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 86% of steel grades. Elongation at break is 33% and the elastic modulus is 213 GPa (30.9 Msi).
What is A369 FP9 used for?
- Refinery high-temperature headers
- Hydrocracker piping
- Catalytic reformer transfer lines
- Fired heater outlet piping
- Sulfidic crude and vacuum unit piping
- Forged fittings for 9Cr-1Mo systems
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- Ductile — tolerates forming and impact — 33%, better than 96% of steel grades
- Good corrosion resistance — 32/100, better than 96% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades
A369 FP9 properties
Typical room-temperature values for A369 FP9-N+T; bars are the position among steel grades.
Physical3
A369 FP9 has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical15
A369 FP9 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 86% of steel grades. Elongation at break is 33% and the elastic modulus is 213 GPa (30.9 Msi).
Thermal6
A369 FP9 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical2
A369 FP9 has an electrical resistivity of 6×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (32/100), better than 96% of steel grades.
Sustainability4
Producing a kilogram of A369 FP9 takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
A369 FP9's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (50/100); formability fair (45/100).
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 FP9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A369 FP9
Is A369 FP9 easy to machine?
Machines like a medium-hard Cr-Mo steel at roughly half the rate of 1212; use rigid setups, carbide inserts, moderate speeds and generous coolant — anneal first for heavy boring.
Can A369 FP9 be welded?
Weld with matching 9Cr-1Mo (E505/ER80S-B8) filler, preheat 200–300 °C, keep interpass hot, and PWHT 730–760 °C to avoid hard untempered martensite and hydrogen cracking.
Can A369 FP9 be formed, bent or molded?
Hot bend/form at 900–1050 °C followed by full re-normalizing and tempering; cold bending is limited and requires post-bend stress relief.
A369 FP9 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 | ≤ 0.15 | 0.1 |
| Mn | 0.3 – 0.6 | 0.45 |
| Si | 0.25 – 1 | 0.6 |
| Cr | 8 – 10 | 9 |
| Mo | 0.9 – 1.1 | 1 |
| Pimpurity limit | ≤ 0.03 | |
| Simpurity limit | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on A369 FP9?
No passive film — shop-prime, paint or metallize for outdoor storage; in service the protective Cr-rich oxide forms above ~400 °C, and coatings must be chosen for the operating temperature.
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 FP9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- A335 P9
How much does A369 FP9 cost?
A369 FP9 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 FP9 — frequently asked
What is A369 FP9 used for?
A369 FP9 is typically used for refinery high-temperature headers, hydrocracker piping, catalytic reformer transfer lines, fired heater outlet piping, sulfidic crude and vacuum unit piping and forged fittings for 9Cr-1Mo systems. In short: highest-chromium A369 pipe; best sulfidation resistance here; hardest to weld in family.
What is the yield strength of A369 FP9?
A369 FP9 has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 2 listed tempers.
Is A369 FP9 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machines like a medium-hard Cr-Mo steel at roughly half the rate of 1212; use rigid setups, carbide inserts, moderate speeds and generous coolant — anneal first for heavy boring.
Can A369 FP9 be welded?
With care — weldability is rated fair (50/100). Weld with matching 9Cr-1Mo (E505/ER80S-B8) filler, preheat 200–300 °C, keep interpass hot, and PWHT 730–760 °C to avoid hard untempered martensite and hydrogen cracking.
What surface finishes work on A369 FP9?
No passive film — shop-prime, paint or metallize for outdoor storage; in service the protective Cr-rich oxide forms above ~400 °C, and coatings must be chosen for the operating temperature.
Can A369 FP9 be formed, bent or molded?
Hot bend/form at 900–1050 °C followed by full re-normalizing and tempering; cold bending is limited and requires post-bend stress relief.
What is the maximum service temperature of A369 FP9?
A369 FP9 is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 FP9 N+T and A369 FP9-A?
N+T is the default condition — standard supply condition for FP9 pressure piping: best creep strength and toughness combination for 500–600 °C service. A: pick when maximum softness/machinability and lowest hardness for field bending or heavy machining are needed; slightly lower strength than N+T. Yield strength is 300 MPa in N+T versus 250 MPa in A.
How much does A369 FP9 cost?
A369 FP9 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 (Grade P9) — ASTM International (2022)
- ASME BPVC Section II Part D — Properties (Metric), 9Cr-1Mo — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.