Steel A369 FP22 N+T
Heat-treated state
ASTM A369 FP22
N+T = normalized and tempered
Choose for higher room-temperature strength and toughness in thick-wall header/piping forgings; bainitic structure with better creep-rupture consistency.
Values for the N+T condition
Other A369 FP22 tempers and conditions
A369 FP22 is listed in 4 conditions; see the grade overview at A369 FP22.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Isothermal annealed | Pick when very uniform low hardness and dimensional stability across heavy wall sections are needed for machining or field bending. | 300 | 490 | 30 | 140 HB | 7.6 % IACS |
AnnealedDefault full anneal per ASTM A369 (heat above upper critical, slow cool) | Standard stocked condition for FP22 forged-and-bored pipe: softest, most machinable, easiest to bend and weld, meets 415/205 MPa minimums. | 305 | 500 | 28 | 145 HB | — |
N+TThis page Normalized and tempered | Choose for higher room-temperature strength and toughness in thick-wall header/piping forgings; bainitic structure with better creep-rupture consistency. | 400 | 585 | 24 | 175 HB | — |
Quenched and tempered | Supplemental condition for heavy-wall hydroprocessing forgings where higher yield strength and low-temperature toughness are specified; requires temper well above service temperature. | 500 | 660 | 22 | 19 HRC | — |
What is A369 FP22 N+T?
A369 FP22 N+T is A369 FP22 heat treated to N+T — choose for higher room-temperature strength and toughness in thick-wall header/piping forgings; bainitic structure with better creep-rupture consistency. A369 FP22 N+T has a yield strength of 400 MPa (58 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 60% of steel grades. Elongation at break is 24% and the elastic modulus is 207 GPa (30 Msi). A369 FP22 N+T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). Annealed is the default condition FabDigit quotes; N+T is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 190 MPa·√m (172.9 ksi·√in), better than 99% of steel grades
- High service temperature — 580°C (1,076 °F), better than 97% of steel grades
A369 FP22 N+T properties
Typical room-temperature values for A369 FP22 N+T; 13 are specific to this condition. Other listed values are A369 FP22 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 FP22 N+T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
A369 FP22 N+T has a yield strength of 400 MPa (58 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 60% of steel grades. Elongation at break is 24% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A369 FP22 N+T is rated for continuous service to 580°C (1,076 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 12.1 µm/m·K (6.72 µin/in·°F).
Electrical3
A369 FP22 N+T conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A369 FP22 N+T takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability7
A369 FP22 N+T's machinability is fair (48/100, worse than 57% of steel grades); weldability good (55/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 FP22 N+T
Is A369 FP22 easy to machine?
Machines like annealed 4140 at ~60 % of 1212 — carbide tooling, rigid setups and generous coolant; keep speeds down in the N+T/Q&T conditions.
Can A369 FP22 be welded?
Weldable with 2.25Cr-1Mo filler (E9018-B3 / ER90S-B3): preheat 200–250 °C, low-hydrogen practice, interpass control, and mandatory PWHT 690–760 °C to avoid hard HAZ and temper embrittlement.
Can A369 FP22 be formed, bent or molded?
Hot bend/form at 900–1050 °C followed by re-heat treatment; cold bending is limited and should be followed by stress relief.
What surface finishes work on A369 FP22?
Not anodizable — use shot blast plus high-temperature aluminium or silicone paint, phosphate, or aluminizing/cladding for steam and sulfidation service.
A369 FP22 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 |
| Si | ≤ 0.5 | 0.3 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.03 | 0.01 |
| Cr | 1.9 – 2.6 | 2.25 |
| Mo | 0.87 – 1.13 | 1 |
| Fe | balance | — |
A369 FP22 N+T — frequently asked
What is A369 FP22 N+T used for?
A369 FP22 N+T is typically used for superheater and reheater headers, refinery high-temperature piping, hydroprocessing and hydrogen-service lines, main steam and hot reheat piping, forged fittings and valve bodies for Cr-Mo systems and fired heater transfer lines. In short: most available Cr-Mo pipe; forged equivalent of P22; standard boiler header grade.
What is the yield strength of A369 FP22 N+T?
A369 FP22 N+T has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A369 FP22 N+T easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machines like annealed 4140 at ~60 % of 1212 — carbide tooling, rigid setups and generous coolant; keep speeds down in the N+T/Q&T conditions.
Can A369 FP22 N+T be welded?
Yes — weldability is rated good (55/100). Weldable with 2.25Cr-1Mo filler (E9018-B3 / ER90S-B3): preheat 200–250 °C, low-hydrogen practice, interpass control, and mandatory PWHT 690–760 °C to avoid hard HAZ and temper embrittlement.
What surface finishes work on A369 FP22 N+T?
Not anodizable — use shot blast plus high-temperature aluminium or silicone paint, phosphate, or aluminizing/cladding for steam and sulfidation service.
Can A369 FP22 N+T be formed, bent or molded?
Hot bend/form at 900–1050 °C followed by re-heat treatment; cold bending is limited and should be followed by stress relief.
What is the maximum service temperature of A369 FP22 N+T?
A369 FP22 N+T is rated for continuous use to about 580°C (1,076 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 FP22 Annealed and A369 FP22-IA?
Annealed is the default condition — standard stocked condition for FP22 forged-and-bored pipe: softest, most machinable, easiest to bend and weld, meets 415/205 MPa minimums. IA: pick when very uniform low hardness and dimensional stability across heavy wall sections are needed for machining or field bending. Yield strength is 305 MPa in Annealed versus 300 MPa in IA.
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 (P22) — ASTM International (2022)
- EN 10216-2 — Seamless steel tubes for pressure purposes (10CrMo9-10, 1.7380) — CEN (2020)
- ASME BPVC Section II Part D — Material properties (2.25Cr-1Mo) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- API RP 941 — Steels for Hydrogen Service at Elevated Temperatures (Nelson curves) — API (2016)
- GB/T 5310 — Seamless steel tubes for high pressure boiler (12Cr2Mo1G) — SAC (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.