ASTM A694 F65 – High-yield steel forging
Forged carbon steel for high-pressure pipeline flanges and fittings
Forged carbon (or low-alloy) steel specified by ASTM A694/A694M, grade F65, with a minimum yield strength of 450 MPa (65 ksi). It is the material for flanges, fittings and forged parts that join API 5L X65 pipe in high-pressure oil and gas transmission pipelines, where A105 (250 MPa yield) cannot match the pipe strength.
Designations and equivalents
| System | Designation |
|---|---|
| Trade names | A694 F65, F65 |
| Others | Matching pipe: API 5L X65 (L450); pipeline flanges MSS SP-44 F65; fittings MSS SP-75 WPHY 65 |
Standards by product form
| Form | Standard |
|---|---|
| Forging (flanges, fittings, valves and parts) | ASTM A694/A694M F65 |
| Common requirements | ASTM A961/A961M; ASTM A788/A788M |
| Flange dimensions | MSS SP-44 / ASME B16.5 / ASME B16.47 |
| Butt-weld fittings | MSS SP-75 WPHY 65 |
| Matching line pipe | API 5L X65 (L450) |
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 |
| 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). ASTM A694 does not require any alloying element above the limits of Chapter 72 Note 1(f), so F65 is classified as non-alloy steel. If the heat certificate shows Ni ≥ 0.30 %, Mo ≥ 0.08 %, V ≥ 0.10 % or Nb ≥ 0.06 %, the alloy steel codes (7228, 7225) apply.
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 A694/A694M (heat analysis)
| Element | Range (%) |
|---|---|
| C | ≤ 0.30* |
| Mn | ≤ 1.60* |
| P | ≤ 0.025 |
| S | ≤ 0.025 |
| Si | 0.15 – 0.35 |
| Cu, Ni, Cr, Mo, V, Nb, B | report on certificate* |
| Fe | balance |
Mechanical properties
Heat treated (normalized, normalized and tempered or quenched and tempered), at room temperature – ASTM A694
| Property | Value |
|---|---|
| Yield strength (0.2%) | ≥ 450 MPa (65 ksi) |
| Tensile strength | ≥ 530 MPa (77 ksi) |
| Elongation (50 mm) | ≥ 20% |
| Charpy V | only when specified in the order (supplementary requirement or customer standard) |
| Max. hardness for H2S service | ≤ 22 HRC (NACE MR0175 / ISO 15156-2) |
Typical physical properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ (typical) |
| Modulus of elasticity | ≈ 205 GPa (typical) |
| Thermal conductivity (20 °C) | ≈ 45 W/m·K (typical)* |
| Thermal expansion (20–100 °C) | ≈ 11.7 µm/m·K (typical)* |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Designed for transmission pipelines at ambient temperature. The standard does not require impact testing: for low-temperature service, order Charpy testing at the minimum design temperature or use a low-temperature material (A350 LF2, A707*). |
| Heat treatment | Mandatory: normalizing, normalizing and tempering, or quenching and tempering (tempering ≥ 540 °C*). In heavy sections, quenching and tempering is the way to reach 450 MPa with good toughness. Post-weld heat treatment must stay below the tempering temperature. |
| Welding | Weldable with a qualified procedure (API 1104 / ASME IX) and filler metal with strength equal to or higher than the X65 pipe. The carbon equivalent is higher than that of A105 and calls for preheating in heavy thicknesses*. Specify CE and microalloy limits in the contract when the forging will be welded to pipe. |
| Machining | Good, close to normalized A105; in the quenched and tempered condition machining is slower. |
Typical applications
- Weld neck (WN) and blind flanges for pipelines (MSS SP-44)
- Forged tees, reducers and fittings for high-pressure pipelines
- Pipeline block valve bodies
- Transition pieces between API 5L X65 pipe and equipment
- Gas compressor and metering stations
Alternatives: A105 when the pipe is a low grade (B, X42) and flange thickness compensates for lower strength; A350 LF2 for low temperature (Charpy at −46 °C), with 250 MPa yield; A694 F60 or F70 to match X60 or X70 pipe.
ASTM A694 F65: complete guide
Why A694 exists
Oil and gas pipelines use high-yield API 5L pipe (X52 to X70). The flange and fitting welded to that pipe need similar strength, otherwise they become thicker and heavier. ASTM A694 covers carbon and low-alloy steel forgings for this service, with nine grades from F42 to F70; the number is the minimum yield strength in ksi. F65 matches X65 pipe and is one of the most requested grades for MSS SP-44 flanges.
A694 F65, A105 and A350 LF2
A105 is the standard flange for industrial piping, with a minimum yield strength of 250 MPa. A350 LF2 has the same strength, with mandatory Charpy testing at −46 °C for low temperature. A694 F65 almost doubles the yield strength (450 MPa) and requires heat treatment, but does not require impact testing unless the purchaser specifies it. For flange dimensions, see the ASME B16.5 flange tables.
Published composition tables vary by edition: some sources give C ≤ 0.26% and Mn ≤ 1.65% for F65*. Check the edition called for in the contract.
Supply forms and Dustre services
Flanges, rings and blocks forged in open die, normalized or quenched and tempered in our own furnaces (heat treatment), with machining and tensile, hardness 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 A694 F65?
Per ASTM A694/A694M (heat analysis): C ≤ 0.30*; Mn ≤ 1.60*; P ≤ 0.025; S ≤ 0.025; Si 0.15 – 0.35; Cu, Ni, Cr, Mo, V, Nb, B report on certificate*.
Which standards cover ASTM A694 F65?
Forging (flanges, fittings, valves and parts): ASTM A694/A694M F65. Common requirements: ASTM A961/A961M; ASTM A788/A788M. Flange dimensions: MSS SP-44 / ASME B16.5 / ASME B16.47. Butt-weld fittings: MSS SP-75 WPHY 65. Matching line pipe: API 5L X65 (L450).
Up to what temperature can ASTM A694 F65 be used?
Designed for transmission pipelines at ambient temperature. The standard does not require impact testing: for low-temperature service, order Charpy testing at the minimum design temperature or use a low-temperature material (A350 LF2, A707*).
Which materials can replace ASTM A694 F65?
A105 when the pipe is a low grade (B, X42) and flange thickness compensates for lower strength; A350 LF2 for low temperature (Charpy at −46 °C), with 250 MPa yield; A694 F60 or F70 to match X60 or X70 pipe.
Is A694 F65 a carbon steel?
Yes, usually a carbon-manganese steel, sometimes microalloyed with niobium or vanadium. The standard limits C, Mn, P, S and Si and requires Cu, Ni, Cr, Mo, V, Nb and B to be reported on the certificate. What defines the grade is the minimum yield strength: 65 ksi (450 MPa).
Can I replace A694 F65 with A105?
Not directly. A105 has a minimum yield strength of 250 MPa, versus 450 MPa for F65. Pipeline flange design assumes the material strength; replacing it requires recalculating the thickness and approval by the designer.
What are the ASTM A694 grades?
F42, F46, F48, F50, F52, F56, F60, F65 and F70. The number is the minimum yield strength in ksi (F42 = 290 MPa; F70 = 485 MPa). The grade is chosen to match the API 5L pipe of the pipeline (X42 to X70).
