Steel A369 FP92 N+T-LT
Heat-treated state
ASTM A369 FP92
Pick when the purchaser wants the top of the strength band (thick headers, high design stress) and can accept hardness near the 250 HB limit.
Values for the N+T-LT condition
Other A369 FP92 tempers and conditions
A369 FP92 is listed in 5 conditions; see the grade overview at A369 FP92.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Intermediate softened state supplied for heavy machining or cold work; must be re-normalized and tempered before pressure service. | 400 | 600 | 26 | 10 HRC | 3 % IACS |
N+T | Use where hardness must stay well below 250 HB (heavy field welding, NDE hardness surveys) and maximum Charpy energy is wanted. | 470 | 655 | 24 | 14 HRC | 2.9 % IACS |
N+TDefault Normalized and tempered | Standard delivery condition for all A369 FP92 pipe — the only state accepted for pressure service. | 510 | 700 | 22 | 19 HRC | — |
N+T-LTThis page N+T | Pick when the purchaser wants the top of the strength band (thick headers, high design stress) and can accept hardness near the 250 HB limit. | 570 | 770 | 19 | 23 HRC | 2.9 % IACS |
As-forged / as-quenched | Condition of the forged and bored shell before final N+T; hard and brittle, listed only for shop handling and machining planning. | 950 | 1,300 | 9 | 43 HRC | 2.5 % IACS |
What is A369 FP92 N+T-LT?
A369 FP92 N+T-LT is A369 FP92 heat treated to N+T-LT — pick when the purchaser wants the top of the strength band (thick headers, high design stress) and can accept hardness near the 250 HB limit. A369 FP92 N+T-LT has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 770 MPa (112 ksi) — stronger than 74% of steel grades. Elongation at break is 19% and the elastic modulus is 218 GPa (31.6 Msi). A369 FP92 N+T-LT has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F). N+T is the default condition FabDigit quotes; N+T-LT is available on request or by drawing note.
Advantages
- High service temperature — 620°C (1,148 °F), better than 99% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
Limitations
- Poor heat conductor — 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Difficult to machine — 35/100, worse than 84% of steel grades
A369 FP92 N+T-LT properties
Typical room-temperature values for A369 FP92 N+T-LT; 23 are specific to this condition. Other listed values are A369 FP92 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 FP92 N+T-LT has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
A369 FP92 N+T-LT has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 770 MPa (112 ksi) — stronger than 74% of steel grades. Elongation at break is 19% and the elastic modulus is 218 GPa (31.6 Msi).
Thermal6
A369 FP92 N+T-LT is rated for continuous service to 620°C (1,148 °F). It conducts heat at 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical2
A369 FP92 N+T-LT has an electrical resistivity of 6×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of A369 FP92 N+T-LT takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability6
A369 FP92 N+T-LT's machinability is fair (35/100, worse than 84% of steel grades); weldability poor (32/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 FP92 N+T-LT
Is A369 FP92 easy to machine?
Machine in the N+T (200–230 HB) state with rigid setups, coated carbide, moderate speed and heavy positive feed; Nb/V carbides are abrasive and the steel work-hardens if feeds are too light.
Can A369 FP92 be welded?
GTAW root + SMAW/FCAW/SAW with matching 9Cr-2W consumables, 200–250 °C preheat, interpass ≤300 °C, cool to <100 °C then PWHT 750–770 °C for 2–4 h; avoid over-alloyed weld metal and minimize heat input to limit Type IV HAZ cracking.
Can A369 FP92 be formed, bent or molded?
Hot bend/forge at 1050–1150 °C followed by full re-normalizing and tempering; cold bending is limited and any significant cold strain requires re-heat treatment.
What surface finishes work on A369 FP92?
Supplied machined/bored or shot-blast finished; use high-temperature aluminide or Al-rich paint plus insulation for outer surfaces — the steel is not stainless and rusts freely in wet ambient storage.
A369 FP92 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 | 0.07 – 0.13 | 0.11 |
| Mn | 0.3 – 0.6 | 0.45 |
| Si | ≤ 0.5 | 0.25 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | 8.5 – 9.5 | 9 |
| Mo | 0.3 – 0.6 | 0.45 |
| Wsolid-solution strengthener, key P92 addition | 1.5 – 2 | 1.75 |
| V | 0.15 – 0.25 | 0.2 |
| Nb | 0.04 – 0.09 | 0.06 |
| N | 0.03 – 0.07 | 0.05 |
| Bstabilizes M23C6 at grain boundaries | 0 – 0.01 | 0 |
| Ni | ≤ 0.4 | 0.15 |
| Allow Al to keep N available for MX | ≤ 0.04 | 0.02 |
| Ti | ≤ 0.01 | — |
| Zr | ≤ 0.01 | — |
| Fe | balance | — |
A369 FP92 N+T-LT — frequently asked
What is A369 FP92 N+T-LT used for?
A369 FP92 N+T-LT is typically used for ultra-supercritical boiler piping, high-pressure steam headers, main steam and hot reheat lines, superheater and reheater outlet headers, forged and bored thick-wall pipe spools and high-temperature pipe fittings and elbows. In short: higher creep strength than P91; 620 °C service capability; most demanding weld procedure.
What is the yield strength of A369 FP92 N+T-LT?
A369 FP92 N+T-LT has a typical yield strength of 570 MPa (82.7 ksi) and a tensile strength of 770 MPa (112 ksi) — stronger than 74% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A369 FP92 N+T-LT easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Machine in the N+T (200–230 HB) state with rigid setups, coated carbide, moderate speed and heavy positive feed; Nb/V carbides are abrasive and the steel work-hardens if feeds are too light.
Can A369 FP92 N+T-LT be welded?
Not readily — weldability is rated poor (32/100). GTAW root + SMAW/FCAW/SAW with matching 9Cr-2W consumables, 200–250 °C preheat, interpass ≤300 °C, cool to <100 °C then PWHT 750–770 °C for 2–4 h; avoid over-alloyed weld metal and minimize heat input to limit Type IV HAZ cracking.
What surface finishes work on A369 FP92 N+T-LT?
Supplied machined/bored or shot-blast finished; use high-temperature aluminide or Al-rich paint plus insulation for outer surfaces — the steel is not stainless and rusts freely in wet ambient storage.
Can A369 FP92 N+T-LT be formed, bent or molded?
Hot bend/forge at 1050–1150 °C followed by full re-normalizing and tempering; cold bending is limited and any significant cold strain requires re-heat treatment.
What is the maximum service temperature of A369 FP92 N+T-LT?
A369 FP92 N+T-LT is rated for continuous use to about 620°C (1,148 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A369 FP92 N+T and A369 FP92-AF?
N+T is the default condition — standard delivery condition for all A369 FP92 pipe — the only state accepted for pressure service. AF: condition of the forged and bored shell before final N+T; hard and brittle, listed only for shop handling and machining planning. Yield strength is 510 MPa in N+T versus 950 MPa in AF.
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 P92) — ASTM International (2022)
- EN 10216-2 — Seamless steel tubes for pressure purposes, X10CrWMoVNb9-2 (1.4901) — CEN (2020)
- ASME BPVC Section II Part D / B31.1 allowable stresses for Grade 92 — ASME (2023)
- NIMS Creep Data Sheet series, 9Cr-1.8W-0.5Mo-VNb steel — NIMS (2014)
- ASM Handbook Vol.1 — Properties of Heat-Resistant Ferritic Steels — ASM International (1990)
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.