ASTM A105 – Forged carbon steel for piping
Carbon-manganese steel for forged flanges, fittings and valves
Forged carbon-manganese steel specified by ASTM A105/A105M for piping components (flanges, fittings, valve bodies) in ambient and elevated temperature service. It is the standard material for ASME B16.5 carbon steel flanges. For service below −29 °C, A350 LF2 is used; for forgings above 4,540 kg, ASTM A266.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | K03504 |
| W.Nr./EN | ≈ P250GH (1.0460) / P280GH (1.0426) – EN 10222-2 |
| DIN | ≈ C22.8 (old) |
| JIS | ≈ S25C / SFVC 2A (JIS G3202) |
| Trade names | A105, SA-105 (ASME) |
| Others | Pipe: A106 Gr B; BW fittings: A234 WPB; casting: A216 WCB |
Standards by product form
| Form | Standard |
|---|---|
| Forging (flanges, fittings, valves) | ASTM A105/A105M; ASME SA-105 |
| Forging > 4,540 kg | ASTM A266 |
| Bar | ASTM A105 (components machined from bar, within the standard's limits) / SAE 1020–1025 |
| Pipe | ASTM A106 Gr B / API 5L B |
| Butt-welding fittings | ASTM A234 WPB |
| Flange dimensions | ASME B16.5 / B16.47 |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7214.10.10 | 7214.10 | 7214.10.0000 | 7214 10 00 |
| Hot-rolled bar | 7214.99.10 | 7214.99 | 7214.99.0036 | 7214 99 71 |
| Seamless pipe | 7304.19.00 | 7304.19 | 7304.19.1030 | 7304 19 10 |
| Welded pipe | 7306.19.00 | 7306.19 | 7306.19.1050 | 7306 19 00 |
| Flange and fitting | 7307.91.00 | 7307.91 | 7307.91.5010 | 7307 91 00 |
Tariff class: non-alloy carbon steel (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
Pipe: 7304.19 and 7306.19 are line pipe for oil and gas pipelines; boiler, heat exchanger or process tubes go under 7304.39/7304.59 (seamless) and 7306.30/7306.50 (welded).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM A105/A105M
| Element | Range (%) |
|---|---|
| C | ≤ 0.35 |
| Mn | 0.60 – 1.05 (*) |
| P | ≤ 0.035 |
| S | ≤ 0.040 |
| Si | 0.10 – 0.35 |
| Cu | ≤ 0.40 |
| Ni | ≤ 0.40 |
| Cr | ≤ 0.30 |
| Mo | ≤ 0.12 |
| V | ≤ 0.08 |
| Nb | ≤ 0.02 |
| Cu+Ni+Cr+Mo+V | ≤ 1.00 |
| Cr+Mo | ≤ 0.32 |
| (*) Mn | +0.06% for each 0.01% of C below 0.35%, up to 1.35% |
Mechanical properties
As forged or heat treated (normalized, N+T or Q+T), room temperature – ASTM A105
| Property | Value |
|---|---|
| Yield strength (0.2%) | ≥ 250 MPa |
| Tensile strength | ≥ 485 MPa |
| Elongation (round specimen 4D) | ≥ 22% (≥ 30% in strip specimen) |
| Reduction of area | ≥ 30% |
| Hardness | ≤ 187 HBW |
Typical physical properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting range | ≈ 1,420 – 1,510 °C |
| Modulus of elasticity | ≈ 203 GPa |
| Thermal conductivity (20 °C) | ≈ 51 W/m·K |
| Thermal expansion (20–100 °C) | ≈ 11.7 µm/m·K |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | −29 °C to ≈ 425 °C in continuous service (ASME B16.5 allows up to 538 °C, but above ≈ 425 °C there is a risk of graphitization/creep). Below −29 °C use A350 LF2. |
| Heat treatment | Mandatory for flanges above Class 300, special-design flanges and other components above NPS 4 and above Class 300: annealing, normalizing (≈ 870–920 °C), normalizing + tempering or quenching + tempering (tempering ≥ 590 °C). Class 150/300 flanges may be supplied as forged. |
| Welding | Good weldability. Electrode AWS E7018 (A5.1), wire ER70S-6 (A5.18), flux-cored wire E71T-1. Preheat of ≈ 80–100 °C for thicknesses > 25 mm or high CE; PWHT at 595–650 °C per code (ASME B31.3/VIII). |
| Machining | Good machinability (≈ 60–65% of 1212), with continuous chips in the normalized condition. |
Filler metal for welding
The wire composition is usually not identical to the material: each page explains why.
Typical applications
- ASME B16.5 flanges (WN, SO, blind, LJ)
- ASME B16.11 forged fittings (socket weld and threaded)
- Valve bodies and bonnets
- Pressure vessel nozzles and couplings
- Non-corrosive water, steam, air, oil and gas lines
- Refineries, petrochemicals and utilities
Alternatives: A350 LF2 for low temperature (Charpy at −46 °C); A694 F52–F65 for high-strength pipeline flanges; A182 F11/F22 above ≈ 425 °C; A182 F304L/F316L or duplex when corrosion is present.
ASTM A105: complete guide
What ASTM A105 steel is
A105 is an ordinary carbon steel, not a special alloy: it contains iron, up to 0.35% carbon, manganese and silicon, with limits on residual elements (Cu, Ni, Cr, Mo, V, Nb). The ASTM A105/A105M standard covers carbon steel forgings for piping components, with a maximum weight of 4,540 kg (10,000 lb) per piece; above that ASTM A266 applies.
Chemical composition and carbon equivalent
Carbon (≤ 0.35%) and manganese (0.60 – 1.05%) control the strength; silicon deoxidizes the steel. The standard limits the sum of residuals and, when the buyer orders supplementary requirement S4 (Carbon Equivalent), the heat's carbon equivalent to 0.47 by the IIW formula up to 2 in (50.8 mm) of section and 0.48 above; a lower value, such as 0.43, may be agreed between buyer and supplier (S4.3), which guarantees the good weldability that makes A105 the most used material in industrial piping.
Mechanical properties
The standard requires a minimum yield strength of 250 MPa, minimum tensile strength of 485 MPa, minimum elongation of 22% in a round specimen, minimum reduction of area of 30% and maximum hardness of 187 HBW. The values apply to the part in its supply condition, as forged or heat treated.
Heat treatment
Contrary to what is often stated, heat treatment is not mandatory in all cases: flanges up to Class 300 and other components up to Class 300 or up to NPS 4 may be supplied as forged. Above that, the standard requires one of the prescribed cycles, and the buyer chooses: annealing, normalizing, normalizing and tempering or quenching and tempering. Dustre performs these cycles in its own furnaces as part of its heat treatment service.
Temperature limits
A105 is not a high-temperature material: recommended continuous use goes up to about 425 °C, above which chromium-molybdenum steels such as F11 and F22 come in. It is also not indicated below −29 °C, a range in which ASTM A350 LF2 is used, with impact testing at −46 °C.
Applications
Flanges of all types and classes, forged fittings, valve bodies and bonnets, blocks, plugs and machined piping parts for water, low-pressure steam, air, oil and gas in refineries, petrochemical plants, the pulp and paper industry, mining and power generation.
Supply forms and Dustre services
Round bars and blocks forged in open die, cut to size on a band saw, with rough or finish machining, heat treatment in our own furnaces and hardness, tensile and impact testing. All material is supplied with a 3.1 inspection certificate and heat traceability.
Frequently asked questions
What is the chemical composition of ASTM A105?
Per ASTM A105/A105M: C ≤ 0.35; Mn 0.60 – 1.05 (*); P ≤ 0.035; S ≤ 0.040; Si 0.10 – 0.35; Cu ≤ 0.40.
Which standards cover ASTM A105?
Forging (flanges, fittings, valves): ASTM A105/A105M; ASME SA-105. Forging > 4,540 kg: ASTM A266. Bar: ASTM A105 (components machined from bar, within the standard's limits) / SAE 1020–1025. Pipe: ASTM A106 Gr B / API 5L B. Butt-welding fittings: ASTM A234 WPB. Flange dimensions: ASME B16.5 / B16.47.
Up to what temperature can ASTM A105 be used?
−29 °C to ≈ 425 °C in continuous service (ASME B16.5 allows up to 538 °C, but above ≈ 425 °C there is a risk of graphitization/creep). Below −29 °C use A350 LF2.
Which materials can replace ASTM A105?
A350 LF2 for low temperature (Charpy at −46 °C); A694 F52–F65 for high-strength pipeline flanges; A182 F11/F22 above ≈ 425 °C; A182 F304L/F316L or duplex when corrosion is present.
