ASME B16.5-2025 material groups and bolting tables

How to read Table 1.1-1

• Column 1 is the material group number. It is the index used throughout Section 2 of the standard, not a quality or strength ranking. The numbering is not consecutive: Groups 1.6, 1.8, 1.12, 1.16 and 3.18 do not appear in the 2025 table.
• Column 2 is a nominal chemical designation (C-Si, 16Cr-12Ni-2Mo, 67Ni-30Cu), not a trade name. The same designation can appear more than once when different product forms are accepted.
• Column 3 names the pressure–temperature rating table for the group. Add a C for the U.S. Customary version: Group 2.13 is rated from Table 2-2.13 in SI units and Table 2-2.13C in U.S. Customary units.
• Columns 4 to 6 list the ASTM specifications the standard accepts by product form. Where the standard prints an ellipsis the cell is shown here as "—".
• Plate materials are listed only for blind flanges and reducing flanges without hubs; additional plate materials in ASME B16.34 may be used with the corresponding B16.34 Standard Class ratings (General Note (b)).
• Materials to ASME Boiler and Pressure Vessel Code, Section II may be used in place of a listed ASTM specification where the ASME requirements are identical to or more stringent than the ASTM ones (Note (1) to Table 1.1-1).
• Temperature limits belong to the rating tables, not to this list: General Note (a) sends the reader to the notes under Tables 2-1.1C through 2-3.17C.

Table 1.1-1 — Group 1 materials

Rows are listed in the order printed in Table 1.1-1, including the cases where a group spans several rows because it accepts several specifications for one product form.

Table 1.1-1 — Group 2 materials

Rows are listed in the order printed in Table 1.1-1, including the cases where a group spans several rows because it accepts several specifications for one product form.

Table 1.1-1 — Group 3 materials

Rows are listed in the order printed in Table 1.1-1, including the cases where a group spans several rows because it accepts several specifications for one product form.

Table 1.1-2 — bolting specifications and their notes

The bolting table is printed as four parallel lists: high strength, intermediate strength, low strength, and nickel and special alloy. The number in each category heading is the note that applies to the whole category; the number in the notes column adds a grade-specific rule. A dash means no extra note is printed for that entry, so only the category note applies.

What the four bolting categories mean

• High strength (note 2): bolting with allowable stresses not less than those of ASTM A193 Grade B7. It may be used in any flanged joint (para. 5.3.2).
• Intermediate strength (note 3): the listed bolting and other bolting of comparable strength. It may be used in any flanged joint provided the user verifies the ability to seat the gasket and keep the joint sealed (para. 5.3.3).
• Low strength (note 4): bolting with a specified minimum yield strength of no more than 206 MPa (30 ksi). It is limited to Class 150 and Class 300 joints (para. 5.3.4) and calls for the gasket practice in para. 5.4.2 and Nonmandatory Appendix B.
• Nickel and special alloy (note 5): bolting for use with comparable nickel and special alloy components; the grade-specific notes (7), (8) and (9) on nuts, operating temperature and forging quality apply.
• General Note (a): bolting must not be used beyond the temperature limits of the governing code. General Note (b): ASME BPVC Section II bolting materials may be used where their requirements are identical to or more stringent than the ASTM specification.
• The strength categories are defined by strength, not by the ASTM designation alone; a grade is listed here because it falls into the category, and the notes decide where it may be used.

Table 1.1-3 — bolting dimensional recommendations

This table is a recommendation, not a dimensional requirement for the flange: it tells the purchaser and the manufacturer which bolt, stud, nut and thread standards go with carbon steel and alloy steel bolting. Section 6.10 refers to it for flange bolting dimensions, and para. 6.10.2 notes that the tabulated stud-bolt lengths in the dimension tables are reference dimensions, so other bolting lengths may be selected.