Steel A369 Grade FPA-ANN (Annealed)
Heat-treated state
ASTM A369 Grade FPA
Softest permitted A369 condition; choose for maximum machinability, cold bending and lowest residual stress in heavy-wall bored pipe.
Values for the ANN condition
Other A369 Grade FPA tempers and conditions
A369 Grade FPA is listed in 3 conditions; see the grade overview at A369 Grade FPA.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNThis page Annealed | Softest permitted A369 condition; choose for maximum machinability, cold bending and lowest residual stress in heavy-wall bored pipe. | 230 | 390 | 38 | 112 HB | — |
N+TDefault Normalized and tempered | Standard supply condition for FPA forged-and-bored pipe: uniform fine ferrite-pearlite with good toughness for boiler/steam header service. | 250 | 415 | 35 | 120 HB | — |
Normalized | Normalize-only condition where slightly higher strength and refined grain are wanted and tempering is not required by the purchaser. | 265 | 430 | 33 | 130 HB | 10 % IACS |
What is A369 Grade FPA-ANN?
A369 Grade FPA-ANN is A369 Grade FPA heat treated to ANN — softest permitted A369 condition; choose for maximum machinability, cold bending and lowest residual stress in heavy-wall bored pipe. A369 Grade FPA-ANN has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 390 MPa (56.6 ksi) — weaker than 97% of steel grades. Elongation at break is 38% and the elastic modulus is 200 GPa (29 Msi). A369 Grade FPA-ANN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F). N+T is the default condition FabDigit quotes; ANN is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 38%, better than 98% of steel grades
- Conducts heat well — 52 W/m·K (30 BTU/hr·ft·°F), better than 98% of steel grades
- Forms and bends easily — 82/100, better than 94% of steel grades
- Easy to machine — 65/100, better than 93% of steel grades
- Readily welded — 92/100, better than 93% of steel grades
Limitations
- Low strength — 230 MPa (33.4 ksi), worse than 97% of steel grades
A369 Grade FPA-ANN properties
Typical room-temperature values for A369 Grade FPA-ANN; 10 are specific to this condition. Other listed values are A369 Grade FPA reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 Grade FPA-ANN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F).
Mechanical16
A369 Grade FPA-ANN has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 390 MPa (56.6 ksi) — weaker than 97% of steel grades. Elongation at break is 38% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A369 Grade FPA-ANN is rated for continuous service to 425°C (797 °F). It conducts heat at 52 W/m·K (30 BTU/hr·ft·°F), better than 98% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
A369 Grade FPA-ANN conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A369 Grade FPA-ANN takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
A369 Grade FPA-ANN's machinability is good (65/100, better than 93% of steel grades); weldability excellent (92/100); formability very good (82/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 Grade FPA-ANN
Is A369 Grade FPA easy to machine?
Free-machining is not present, but low carbon means easy turning/boring at ~65 % of AISI 1212; use positive rake and good chip control to avoid stringy chips in annealed material.
Can A369 Grade FPA be welded?
Excellent weldability (CE ≈ 0.35); SMAW/GTAW with E7018 or ER70S-2, preheat 100–150 °C for walls above ~30 mm and PWHT per ASME B31.1 for heavy sections.
Can A369 Grade FPA be formed, bent or molded?
Hot bend or hot form above 900 °C for heavy-wall pipe, then re-heat-treat; cold bending is possible in the annealed condition with generous radii.
What surface finishes work on A369 Grade FPA?
No anodizing; protect with shop primer, aluminium metallizing or high-temperature silicone paint, and insulate to avoid corrosion-under-insulation.
A369 Grade FPA 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 |
|---|---|---|
| CASTM A369 Grade FPA | ≤ 0.25 | 0.2 |
| Mn | 0.27 – 0.93 | 0.6 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Si0.10 % minimum, no maximum specified | ≥ 0.1 | 0.2 |
| Fe | balance | — |
A369 Grade FPA-ANN — frequently asked
What is A369 Grade FPA-ANN used for?
A369 Grade FPA-ANN is typically used for boiler steam piping, high-temperature pressure pipe and power plant headers. In short: most weldable A369 grade; lowest-strength A369 pipe; easy-boring forged pipe.
What is the yield strength of A369 Grade FPA-ANN?
A369 Grade FPA-ANN has a typical yield strength of 230 MPa (33.4 ksi) and a tensile strength of 390 MPa (56.6 ksi) — weaker than 97% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A369 Grade FPA-ANN easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Free-machining is not present, but low carbon means easy turning/boring at ~65 % of AISI 1212; use positive rake and good chip control to avoid stringy chips in annealed material.
Can A369 Grade FPA-ANN be welded?
Yes — weldability is rated excellent (92/100). Excellent weldability (CE ≈ 0.35); SMAW/GTAW with E7018 or ER70S-2, preheat 100–150 °C for walls above ~30 mm and PWHT per ASME B31.1 for heavy sections.
What surface finishes work on A369 Grade FPA-ANN?
No anodizing; protect with shop primer, aluminium metallizing or high-temperature silicone paint, and insulate to avoid corrosion-under-insulation.
Can A369 Grade FPA-ANN be formed, bent or molded?
Hot bend or hot form above 900 °C for heavy-wall pipe, then re-heat-treat; cold bending is possible in the annealed condition with generous radii.
What is the maximum service temperature of A369 Grade FPA-ANN?
A369 Grade FPA-ANN is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 Grade FPA N+T and A369 Grade FPA-ANN?
N+T is the default condition — standard supply condition for FPA forged-and-bored pipe: uniform fine ferrite-pearlite with good toughness for boiler/steam header service. ANN: softest permitted A369 condition; choose for maximum machinability, cold bending and lowest residual stress in heavy-wall bored pipe. Yield strength is 250 MPa in N+T versus 230 MPa in ANN.
Sources
- ASTM A369/A369M — Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service — ASTM International (2018)
- ASME BPVC Section II Part D — Properties (Metric) — ASME (2023)
- ASME B31.1 Power Piping — ASME (2022)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
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.