ASME B16.47 · Standard reference
ASME B16.47-2025 material groups (Table 1)
ASME B16.47-2025 sorts every permitted flange material into a numbered group, and the group number — not the individual grade — selects the pressure–temperature table. Table 1 (pp. 11-12) lists 27 groups: 1.1 through 1.18 for ferritic carbon and low-alloy steels, and 2.1 through 2.13 for austenitic and duplex stainless steels, together with the forging, casting and plate specifications accepted for each group.
The group also decides which of Tables 3-29 applies to a flange. A105 forgings, for example, are group 1.1 and share Table 3/3C with A216 WCB castings and A515 Gr. 70 plate, while A182 F316L forgings are group 2.3 and read Table 19/19C. Plate materials are only permitted for blind flanges and reducing flanges without hubs (para. 5.1 and Note 1 of Table 1). Group numbering is historical and not consecutive: 1.6, 1.8, 1.12 and 1.16 are not used in this edition.
- Source
- Table 1, pp. 11-12
- Material groups
- 27 (1.1-1.18 and 2.1-2.13)
- Rating tables
- Tables 3-29 (SI) and 3C-29C (US)
- Group 1.1
- A105 / A216 WCB / A515 Gr. 70
- Group 2.3
- A182 F304L, F316L, F317L
- Plate restriction
- Blind and hubless reducing flanges only
Table 1 — material groups and applicable ASTM specifications
Groups 1.x are ferritic; groups 2.x are austenitic and duplex stainless. The column headed 'P/T table' is the rating table pair that governs the group (Tables 3-29 in SI units, 3C-29C in U.S. customary units). Where the standard prints '...' for a product form, it is shown here as '—'.
B16.47 · ASME B16.47-2025
| Group | Nominal designation | Forgings | Castings | Plates | P/T table |
|---|---|---|---|---|---|
| 1.1 | C-Si | A105 | A216 Gr. WCB | A515 Gr. 70 | 3 / 3C |
| 1.1 | C-Mn-Si | A350 Gr. LF2 | — | A516 Gr. 70 | 3 / 3C |
| 1.1 | C-Mn-Si | — | — | A537 Cl. 1 | 3 / 3C |
| 1.1 | C-Mn-Si-V | A350 Gr. LF6 Cl. 1 | — | — | 3 / 3C |
| 1.1 | 3½Ni | A350 Gr. LF3 | — | — | 3 / 3C |
| 1.2 | C-Mn-Si | — | A216 Gr. WCC | — | 4 / 4C |
| 1.2 | C-Mn-Si | — | A352 Gr. LCC | — | 4 / 4C |
| 1.2 | C-Mn-Si-V | A350 Gr. LF6 Cl. 2 | — | — | 4 / 4C |
| 1.2 | 2½Ni | — | A352 Gr. LC2 | A203 Gr. B | 4 / 4C |
| 1.2 | 3½Ni | — | A352 Gr. LC3 | A203 Gr. E | 4 / 4C |
| 1.3 | C-Si | — | A352 Gr. LCB | A515 Gr. 65 | 5 / 5C |
| 1.3 | C-Mn-Si | — | — | A516 Gr. 65 | 5 / 5C |
| 1.3 | 2½Ni | — | — | A203 Gr. A | 5 / 5C |
| 1.3 | 3½Ni | — | — | A203 Gr. D | 5 / 5C |
| 1.3 | C-½Mo | — | A217 Gr. WC1 | — | 5 / 5C |
| 1.3 | C-½Mo | — | A352 Gr. LC1 | — | 5 / 5C |
| 1.4 | C-Si | — | — | A515 Gr. 60 | 6 / 6C |
| 1.4 | C-Mn-Si | A350 Gr. LF1 Cl. 1 | — | A516 Gr. 60 | 6 / 6C |
| 1.5 | C-½Mo | A182 Gr. F1 | — | A204 Gr. A | 7 / 7C |
| 1.5 | C-½Mo | — | — | A204 Gr. B | 7 / 7C |
| 1.7 | ½Cr-½Mo | A182 Gr. F2 | — | — | 8 / 8C |
| 1.7 | Ni-½Cr-½Mo | — | A217 Gr. WC4 | — | 8 / 8C |
| 1.7 | ¾Ni-¾Cr-1Mo | — | A217 Gr. WC5 | — | 8 / 8C |
| 1.9 | 1¼Cr-½Mo | — | A217 Gr. WC6 | — | 9 / 9C |
| 1.9 | 1¼Cr-½Mo-Si | A182 Gr. F11 Cl. 2 | — | A387 Gr. 11 Cl. 2 | 9 / 9C |
| 1.10 | 2¼Cr-1Mo | A182 Gr. F22 Cl. 3 | A217 Gr. WC9 | A387 Gr. 22 Cl. 2 | 10 / 10C |
| 1.11 | 3Cr-1Mo | A182 F21 | — | A387 Gr. 21 Cl. 2 | 11 / 11C |
| 1.11 | C-½Mo | — | — | A240 Gr. C | 11 / 11C |
| 1.13 | 5Cr-½Mo | A182 Gr. F5A | A217 Gr. C5 | — | 12 / 12C |
| 1.14 | 9Cr-1Mo | A182 Gr. F9 | A217 Gr. C12 | — | 13 / 13C |
| 1.15 | 9Cr-1Mo-V | A182 Gr. F91 Type 1 | A217 Gr. C12A | A387 Gr. 91 Cl. 2 | 14 / 14C |
| 1.17 | 1Cr-½Mo | A182 Gr. F12 Cl. 2 | — | — | 15 / 15C |
| 1.17 | 5Cr-½Mo | A182 Gr. F5 | — | — | 15 / 15C |
| 1.18 | 9Cr-2W-V | A182 Gr. F92 | — | — | 16 / 16C |
| 2.1 | 18Cr-8Ni | A182 Gr. F304 | A351 Gr. CF3 | A240 Gr. 304 | 17 / 17C |
| 2.1 | 18Cr-8Ni | A182 Gr. F304H | A351 Gr. CF8 | A240 Gr. 304H | 17 / 17C |
| 2.2 | 16Cr-12Ni-2Mo | A182 Gr. F316 | A351 Gr. CF3M | A240 Gr. 316 | 18 / 18C |
| 2.2 | 16Cr-12Ni-2Mo | A182 Gr. F316H | A351 Gr. CF8M | A240 Gr. 316H | 18 / 18C |
| 2.2 | 18Cr-13Ni-3Mo | A182 Gr. F317 | — | A240 Gr. 317 | 18 / 18C |
| 2.2 | 19Cr-10Ni-3Mo | — | A351 Gr. CG8M | — | 18 / 18C |
| 2.3 | 18Cr-8Ni | A182 Gr. F304L | — | A240 Gr. 304L | 19 / 19C |
| 2.3 | 16Cr-12Ni-2Mo | A182 Gr. F316L | — | A240 Gr. 316L | 19 / 19C |
| 2.3 | 18Cr-13Ni-3Mo | A182 Gr. F317L | — | — | 19 / 19C |
| 2.4 | 18Cr-10Ni-Ti | A182 Gr. F321 | — | A240 Gr. 321 | 20 / 20C |
| 2.4 | 18Cr-10Ni-Ti | A182 Gr. F321H | — | A240 Gr. 321H | 20 / 20C |
| 2.5 | 18Cr-10Ni-Cb | A182 Gr. F347 | — | A240 Gr. 347 | 21 / 21C |
| 2.5 | 18Cr-10Ni-Cb | A182 Gr. F347H | — | A240 Gr. 347H | 21 / 21C |
| 2.5 | 18Cr-10Ni-Cb | A182 Gr. F348 | — | A240 Gr. 348 | 21 / 21C |
| 2.5 | 18Cr-10Ni-Cb | A182 Gr. F348H | — | A240 Gr. 348H | 21 / 21C |
| 2.6 | 23Cr-12Ni | — | — | A240 Gr. 309H | 22 / 22C |
| 2.7 | 25Cr-20Ni | A182 Gr. F310H | — | A240 Gr. 310H | 23 / 23C |
| 2.8 | 20Cr-18Ni-6Mo | A182 Gr. F44 | A351 Gr. CK3MCuN | A240 Gr. S31254 | 24 / 24C |
| 2.9 | 23Cr-12Ni | — | — | A240 Gr. 309S | 25 / 25C |
| 2.9 | 25Cr-20Ni | — | — | A240 Gr. 310S | 25 / 25C |
| 2.10 | 25Cr-12Ni | — | A351 Gr. CH8 | — | 26 / 26C |
| 2.10 | 25Cr-12Ni | — | A351 Gr. CH20 | — | 26 / 26C |
| 2.11 | 18Cr-10Ni-Cb | — | A351 Gr. CF8C | — | 27 / 27C |
| 2.12 | 25Cr-20Ni | — | A351 Gr. CK20 | — | 28 / 28C |
| 2.13 | 22Cr-5Ni-3Mo-N | A182 Gr. F51 | A995 CD3MN (4A) | A240 Gr. S31803 | 29 / 29C |
| 2.13 | 22Cr-5Ni-3Mo-N | A182 Gr. F60 | — | — | 29 / 29C |
| 2.13 | 22Cr-5Ni-3Mo-N | — | — | A240 Gr. S32205 | 29 / 29C |
| 2.13 | 25Cr-5Ni-3Mo-2Cu | — | — | A240 Gr. S32550 | 29 / 29C |
| 2.13 | 25Cr-7Ni-4Mo-N | A182 Gr. F53 | — | A240 Gr. S32750 | 29 / 29C |
| 2.13 | 24Cr-10Ni-4Mo-N | — | A995 Gr. CE8MN (2A) | — | 29 / 29C |
| 2.13 | 25Cr-5Ni-3Cu-2Mo-N | — | A995 Gr. CD4MCuN (1B) | — | 29 / 29C |
| 2.13 | 25Cr-7Ni-3.5Mo-W-Cb | — | A995 Gr. CD3MWCuN (6A) | — | 29 / 29C |
| 2.13 | 25Cr-7Ni-3.5Mo-N-Cu-W | A182 Gr. F55 | — | A240 Gr. S32760 | 29 / 29C |
Plate materials are listed only for blind flanges and reducing flanges without hubs (Note 1). Upper temperature limits are in the notes to Tables 3-28; lower temperature limits are discussed in para. 2.5.3.
How a material group is used
Write the group number into the specification alongside the grade. A flange drawing that says only 'A105' or 'F316L' leaves the rating open to interpretation if the specification is revised; 'A105, group 1.1' or 'F316L, group 2.3' ties the component to the exact rating table used in the design calculation.
The group is also the natural cross-check between forgings, castings and plate. A group can contain several product forms with the same allowable stresses, which is why a casting (A216 WCB) and a forging (A105) can both read Table 3. Mixing product forms is legitimate; mixing groups is not. If a grade appears in more than one group, use the group the mill certificate and the design calculation are based on, and make sure the marking and the certificate agree.
ASME B16.47 material groups — questions
Which material group is ASTM A105?
A105 forgings are group 1.1, the same group as A216 Gr. WCB castings and A515 Gr. 70 plate. Their pressure–temperature rating is Table 3 in bar or Table 3C in psig, with an ambient Class 150 rating of 19.6 bar (285 psig).
Which group are 316 and 316L?
A182 F316 and F316H forgings, together with A240 316/316H plate, are group 2.2. The low-carbon grades A182 F316L and A240 316L are group 2.3. They do not share a rating table, so check the exact grade rather than assuming all '316' flanges behave alike.
Can a weld-neck flange be made from A515 Gr. 70 plate?
No. B16.47 lists plate specifications in Table 1, but para. 5.1 and Note 1 of Table 1 restrict plate to blind flanges and reducing flanges without hubs. A weld-neck flange must be forged or cast in a listed specification and must be made as one piece; assembling it from plate or by welding is not permitted.
Why are groups 1.6, 1.8, 1.12 and 1.16 missing?
The group numbering is historical and shared with the ASME B16.5 material system, so not every number is used in B16.47-2025. Use the group printed in Table 1 for the exact specification and grade; do not infer a group from the sequence or from an older catalogue.