Steel A369 FP1-ANN (Annealed)
Heat-treated state · default condition
ASTM A369 FP1
Standard stocked condition for forged-and-bored FP1 pipe: softest, most machinable, best for cold bending and subsequent welding.
Values for the ANN condition
Other A369 FP1 tempers and conditions
A369 FP1 is listed in 4 conditions; see the grade overview at A369 FP1.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefaultThis page Annealed | Standard stocked condition for forged-and-bored FP1 pipe: softest, most machinable, best for cold bending and subsequent welding. | 270 | 460 | 34 | 140 HB | — |
Stress relieved | Supplementary supply condition for heavy bored sections where residual stress from forging/boring or field welding must be reduced without a full re-austenitization. | 295 | 490 | 30 | 155 HB | 8.2 % IACS |
Normalized and Tempered | Code-preferred condition for high-temperature pressure piping: balanced strength, good toughness and dimensionally stable microstructure for creep service. | 300 | 480 | 32 | 150 HB | — |
Normalized | Choose when finer ferrite-pearlite grain and slightly higher strength/toughness are wanted; usually followed by tempering for pressure service. | 310 | 500 | 30 | 158 HB | — |
What is A369 FP1-ANN?
A369 FP1-ANN is A369 FP1 heat treated to ANN — standard stocked condition for forged-and-bored FP1 pipe: softest, most machinable, best for cold bending and subsequent welding. A369 FP1-ANN has a yield strength of 270 MPa (39.2 ksi) and a tensile strength of 460 MPa (66.7 ksi) — weaker than 91% of steel grades. Elongation at break is 34% and the elastic modulus is 210 GPa (30.5 Msi). A369 FP1-ANN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,470°C (2,678 °F).
Advantages
- Ductile — tolerates forming and impact — 34%, better than 97% of steel grades
- High service temperature — 470°C (878 °F), better than 87% of steel grades
- Forms and bends easily — 70/100, better than 86% of steel grades
- Readily welded — 72/100, better than 75% of steel grades
Limitations
- Low strength — 270 MPa (39.2 ksi), worse than 91% of steel grades
A369 FP1-ANN properties
Typical room-temperature values for A369 FP1-ANN; 12 are specific to this condition. Other listed values are A369 FP1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 FP1-ANN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,470°C (2,678 °F).
Mechanical15
A369 FP1-ANN has a yield strength of 270 MPa (39.2 ksi) and a tensile strength of 460 MPa (66.7 ksi) — weaker than 91% of steel grades. Elongation at break is 34% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
A369 FP1-ANN is rated for continuous service to 470°C (878 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical2
A369 FP1-ANN has an electrical resistivity of 2.1×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of A369 FP1-ANN takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
A369 FP1-ANN's machinability is good (60/100, better than 83% of steel grades); weldability very good (72/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 FP1-ANN
Is A369 FP1 easy to machine?
Machines like annealed 4130-class low-alloy steel at ~60 % of AISI 1212; use rigid setups and positive-rake carbide for boring long heavy-wall sections, and expect slightly gummy chips in the fully annealed state.
Can A369 FP1 be welded?
Readily welded with matching Mo-bearing consumables (E7018-A1, ER80S-D2); preheat 120–200 °C on heavy wall and apply 650–720 °C PWHT per ASME B31.1 to restore toughness and control hardness.
Can A369 FP1 be formed, bent or molded?
Hot forge/bend at 950–1200 °C and re-heat-treat afterwards; cold bending is possible with generous radii but work-hardens and needs stress relief.
What surface finishes work on A369 FP1?
No anodizing; protect with alkyd/epoxy or high-temperature aluminium paint, aluminizing or thermal-spray coating, and expect mill scale removal by pickling or blasting before painting.
A369 FP1 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 |
|---|---|---|
| C16Mo3 range 0.12–0.20 | 0.1 – 0.2 | 0.16 |
| Si | 0.1 – 0.5 | 0.3 |
| Mn | 0.3 – 0.8 | 0.6 |
| P | ≤ 0.05 | 0.02 |
| S | ≤ 0.05 | 0.01 |
| Mothe C-0.5Mo creep-strengthening addition | 0.44 – 0.65 | 0.5 |
| Fe | balance | — |
A369 FP1-ANN — frequently asked
What is A369 FP1-ANN used for?
A369 FP1-ANN is typically used for high-temperature steam piping, header pipe fittings, superheater and reheater connecting piping, main steam and feedwater headers, refinery hot-oil transfer lines and forged pipe spools for power plants. In short: entry-level Mo creep pipe; 470 °C service limit; most weldable A369 grade.
What is the yield strength of A369 FP1-ANN?
A369 FP1-ANN has a typical yield strength of 270 MPa (39.2 ksi) and a tensile strength of 460 MPa (66.7 ksi) — weaker than 91% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A369 FP1-ANN easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machines like annealed 4130-class low-alloy steel at ~60 % of AISI 1212; use rigid setups and positive-rake carbide for boring long heavy-wall sections, and expect slightly gummy chips in the fully annealed state.
Can A369 FP1-ANN be welded?
Yes — weldability is rated very good (72/100). Readily welded with matching Mo-bearing consumables (E7018-A1, ER80S-D2); preheat 120–200 °C on heavy wall and apply 650–720 °C PWHT per ASME B31.1 to restore toughness and control hardness.
What surface finishes work on A369 FP1-ANN?
No anodizing; protect with alkyd/epoxy or high-temperature aluminium paint, aluminizing or thermal-spray coating, and expect mill scale removal by pickling or blasting before painting.
Can A369 FP1-ANN be formed, bent or molded?
Hot forge/bend at 950–1200 °C and re-heat-treat afterwards; cold bending is possible with generous radii but work-hardens and needs stress relief.
What is the maximum service temperature of A369 FP1-ANN?
A369 FP1-ANN is rated for continuous use to about 470°C (878 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 FP1-ANN and A369 FP1-N?
ANN is the default condition — standard stocked condition for forged-and-bored FP1 pipe: softest, most machinable, best for cold bending and subsequent welding. N: choose when finer ferrite-pearlite grain and slightly higher strength/toughness are wanted; usually followed by tempering for pressure service. Yield strength is 270 MPa in ANN versus 310 MPa in N.
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 P1) — ASTM International (2022)
- EN 10216-2 — Seamless steel tubes for pressure purposes (16Mo3, 1.5415) — CEN (2020)
- ASME BPVC Section II Part D — Allowable stresses and physical properties — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- 16Mo3 / 1.5415 pressure-vessel and boiler tube steel datasheets — various European tube producers (2022)
- API RP 941 — Steels for Hydrogen Service (graphitization guidance for C-0.5Mo) — API (2016)
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.