Overview
ASTM A105/A105M specifies a single grade of forged carbon steel for pressure-containing piping components in ambient- and elevated-temperature service. It is the common material specification behind carbon-steel flanges, forged socket-weld and threaded fittings, valve bodies or bonnets, and similar forged parts used in refineries, chemical plants, utilities, and general process piping. The specification controls material manufacture, chemical composition, mechanical properties, heat treatment, testing, repair, and marking. It does not establish component dimensions or pressure-temperature ratings: an A105 flange is normally ordered to ASME B16.5 or ASME B16.47, while A105 forged fittings are normally ordered to ASME B16.11. The finished component must satisfy both its material specification and its applicable dimensional standard. A105 forgings are limited to 10,000 lb (4,540 kg) each. Larger forgings are directed to ASTM A266/A266M. Because the base specification does not require Charpy impact testing, suitability at a low design metal temperature must be checked under the governing construction code; ASTM A350 LF2 is the usual impact-tested alternative when notch toughness is required.
Scope & Applicability
Applies To Industries
Covers — one grade of forged carbon steel for pressure-system components in ambient- and higher-temperature service:
- Flanges, forged fittings, valves, bonnets, nozzles, and similar pressure-containing parts.
- Individually forged components weighing no more than 10,000 lb (4,540 kg).
- Parts ordered to purchaser drawings or to dimensional standards such as ASME B16.5, B16.11, and B16.47.
- Limited finished parts machined from rolled bar or seamless tubular product where permitted by the product rules.
Does NOT cover (exclusions) — the following are governed elsewhere:
- Finished-component dimensions and pressure-temperature ratings: use ASME B16.5 / B16.11 / B16.47 as applicable.
- Low-temperature forgings requiring notch-toughness testing: use ASTM A350/A350M, commonly Grade LF2.
- Alloy-steel or stainless-steel forgings: use ASTM A182/A182M.
- Carbon-steel castings rather than forgings: use ASTM A216/A216M.
- Forgings over 10,000 lb (4,540 kg), tubesheets, or hollow pressure-vessel shell forgings: use ASTM A266/A266M.
- Raw rolled bar or raw seamless tubular stock: use ASTM A675/A675M, ASTM A696, or the applicable tubular specification.
[!IMPORTANT] ASTM A105/A105M is a material specification, not a flange class or dimensional standard. Marking a part “A105” alone does not establish its Class, dimensions, facing, or pressure-temperature rating.
Key Requirements
The acceptance checks below identify the core A105/A105M requirements; the purchase order and adopted edition remain controlling:
- Carbon and manganese: carbon is limited to 0.35% max; manganese is 0.60–1.05% under the base chemistry limits.
- Other chemistry limits: phosphorus 0.035% max, sulfur 0.040% max, and silicon 0.10–0.35%; residual Cu, Ni, Cr, Mo, and V are also controlled.
- Tensile strength: minimum 70 ksi (485 MPa).
- Yield strength: minimum 36 ksi (250 MPa) at 0.2% offset.
- Ductility: minimum elongation is 22% in 2 in. (50 mm), with reduction of area at least 30%.
- Hardness: maximum 187 HBW.
- Product mass: each forging is limited to 10,000 lb (4,540 kg); larger forgings fall under ASTM A266/A266M.
- Testing and heat treatment: tension and hardness testing are required; hydrostatic testing applies when required by the product or order. Permitted heat treatments include annealing, normalizing, normalizing and tempering, and quenching and tempering.
Technical Details
Use these tables as an engineering screening aid; confirm acceptance against the purchased ASTM edition and the governing construction code.
1. Chemical composition limits
| Element | A105/A105M limit |
|---|---|
| Carbon (C) | 0.35% max |
| Manganese (Mn) | 0.60–1.05% |
| Phosphorus (P) | 0.035% max |
| Sulfur (S) | 0.040% max |
| Silicon (Si) | 0.10–0.35% |
| Copper (Cu) | 0.40% max |
| Nickel (Ni) | 0.40% max |
| Chromium (Cr) | 0.30% max |
| Molybdenum (Mo) | 0.12% max |
| Vanadium (V) | 0.08% max |
2. Mechanical acceptance properties
| Property | Minimum / maximum requirement |
|---|---|
| Tensile strength | 70 ksi (485 MPa) minimum |
| Yield strength, 0.2% offset | 36 ksi (250 MPa) minimum |
| Elongation in 2 in. (50 mm) | 22% minimum |
| Reduction of area | 30% minimum |
| Hardness | 187 HBW maximum |
3. Common material-selection matrix
| Service or product | Usual material specification | Key distinction |
|---|---|---|
| Ambient / elevated-temperature forged carbon-steel piping part | ASTM A105/A105M | One carbon-steel forging grade; no base Charpy requirement |
| Low-temperature forged piping part | ASTM A350/A350M LF2 | Notch-toughness testing and low-temperature heat-treatment controls |
| Alloy or stainless forged piping part | ASTM A182/A182M | Multiple F-grades for high temperature or corrosion resistance |
| Carbon-steel cast valve / pressure part | ASTM A216/A216M WCB | Casting specification, not forging |
| High-strength transmission-service forging | ASTM A694/A694M | F-grades selected by minimum yield strength |
Engineering Notes
Five field and procurement checks prevent the most common A105 selection errors:
1. Check MDMT; “below ambient” is not a complete rejection rule
ASTM A105/A105M does not impose a base Charpy impact test. The governing code, component thickness, heat treatment, stress level, and minimum design metal temperature (MDMT) determine whether an exemption is available.
[!WARNING] Never accept A105 for cold service solely because the flange pressure Class is adequate. Perform the governing-code brittle-fracture check; where notch toughness is required, specify ASTM A350/A350M LF2 with the required impact-test temperature and energy.
2. Do not derive pressure rating from the material stamp
“A105” confirms the material specification only. The allowable pressure at temperature comes from the component standard and adopted code—typically ASME B16.5 or B16.47 for flanges—and depends on Class, temperature, geometry, and edition.
3. Review the MTR numerically
Match the heat number and verify C ≤ 0.35%, tensile strength ≥ 70 ksi (485 MPa), yield strength ≥ 36 ksi (250 MPa), and hardness ≤ 187 HBW. Confirm the reported heat treatment and any ordered supplementary requirements.
4. Treat repair welding as a controlled activity
Repair by welding is not an informal shop fix. Confirm that the purchased edition, purchaser approval, qualified WPS/PQR and welder, compatible filler metal, examination, and any required post-weld heat treatment are satisfied before acceptance.
5. Keep ASTM and ASME unit systems explicit
A105 and A105M values are independently standard, not exact conversion pairs. State the required designation and do not mix acceptance values from the inch-pound and SI systems on one inspection decision.
Source, Edition & Status
- Publisher
- ASTM
- Edition Year
- 2026
- Industries
- Petrochemical, Refinery, Chemical Plant, Power Plant, General Industry
- Last Reviewed
- 2026-07-01
- Last Updated
- 2026-07-01
- Verified By
- Engineering content reviewer
- Content Status
- reviewed
- Official Link
- store.astm.org