ASME B16.47 · Standard reference
ASME B16.47-2025 changes and record numbers
ASME B16.47-2025 was approved by the American National Standards Institute on 4 March 2025 and issued on 30 May 2025, succeeding B16.47-2020; the next edition is scheduled for 2028. The Foreword (pp. vi-vii) and the Summary of Changes (pp. xi-xiv) set out what moved, and each changed clause or table in the body of the standard carries a margin note marked '(25)'.
The changes that matter most commercially are the revised pressure–temperature ratings throughout Tables 3-28 and the new Table 29/29C for Group 2.13 duplex stainless steels. Dimension tables were also renumbered by one place — Tables 32-42 were formerly Tables 31-41 — so references copied from older drawings or specifications need checking. The record numbers in the second table are the standard's own change identifiers and can be quoted in technical queries.
- Approved
- 4 March 2025 (ANSI)
- Issued
- 30 May 2025
- Follows
- ASME B16.47-2020
- New rating table
- 29 / 29C, Group 2.13 duplex
- Ratings
- Revised throughout Tables 3-28
- Change records
- 9 listed for this edition
What changed in the 2025 edition
The Summary of Changes lists each location, whether it was added or revised, and the record number behind it. The table groups those entries by subject and adds the practical effect for a buyer or designer.
B16.47 · ASME B16.47-2025
| Area | Change in the 2025 edition | Impact for buyers |
|---|---|---|
| Edition status | ANSI approval on 4 March 2025; issue date 30 May 2025; next edition scheduled for 2028. | Quote ASME B16.47-2025 on new orders; confirm which edition an existing drawing calls up. |
| Unit-system table titles | Titles of the complementary SI and U.S. Customary tables were editorially revised to name the applicable unit system. | It is now unambiguous which table is bar and which is psig; no rating or dimension changed for this item alone. |
| Pressure–temperature ratings | Working-pressure values and the accompanying notes were revised throughout Tables 3-28 and 3C-28C (record 23-2374). | Ratings can differ from B16.47-2020. Re-check the allowable pressure at the design temperature against the 2025 tables. |
| Group 2.13 duplex stainless | A new Table 29 / 29C was added for Group 2.13 materials (duplex and super-duplex grades). | Duplex flanges now have a dedicated rating table rather than a cross-reference; check the grade against Table 1. |
| Table 1 materials | Table 1 was revised (records 21-1888 and 23-2374). | Confirm the material group number of your grade before reading a rating table; a different group means a different table. |
| Bolting | ASTM A320-L7M was added to Table 2 and Note (5) was revised (record 22-651). | An additional low-temperature bolting option is now listed; bolting must still suit the flange material and service temperature. |
| Table 2 notes | Note (7) was deleted and the subsequent notes renumbered (record 21-1888). | If a QA document quotes a Table 2 note number, re-check it against the 2025 print. |
| Definitions | A new para. 1.13 defines 'may', 'shall' and 'should' (record 22-2279), and 'must' was replaced in two clauses. | Requirement wording is more consistent; no technical requirement changed for this item alone. |
| Metric note temperatures | In the notes to Tables 3-6, 21 and 25, metric temperatures were revised to the nearest degree (record 22-2277). | Note-level temperature limits may read slightly differently; use the rounded °C value in the 2025 print. |
| Table numbering | The new Table 29/29C displaced the later tables: dimension Tables 32-42 were formerly Tables 31-41, and the 'Minimum Thickness of Flange, t' subheadings were editorially revised. | Update drawing and specification references; a reference to 'Table 35' in an old document may now be Table 36. |
| Rating ceilings (non-mandatory) | Ceiling pressures for Classes 300-900 in Table A-1 / A-1C were revised (record 22-2110). | Affects the non-mandatory rating-ceiling appendix, not the mandatory Tables 3-29 ratings. |
| Errata incorporated | Table 20: Class 150 working pressure at 400 °C corrected to 5.5 bar (record 22-203). Table 36: minimum thickness for an NPS 30 weld-neck corrected to 149.4 mm (record 22-99). | If you hold an earlier print, these two values may be wrong in your copy; the 2025 print carries the corrections. |
| References | The References section and the references in Mandatory Appendix I were updated (records 23-2265 and 21-1888). | Cited editions of related standards changed; check the new reference list when writing specifications. |
The standard's own margin note for 2025 changes is '(25)'. Record numbers are listed in the order the standard presents them, not by importance.
Change record numbers in this edition
The standard lists nine record numbers for the 2025 edition. Each number points to the clauses and tables it revised, and the number can be used when raising a technical query or checking a certificate of conformance to a particular print.
B16.47 · ASME B16.47-2025
| Record number | Scope |
|---|---|
| 21-1888 | Revised paras. 2.4, 2.5.3 and 5.3.4, Table 1 and Table 2, Tables 3-28 (3C-28C) and Table A-1 (A-1C, formerly Table A-2); updated references in Mandatory Appendix I. |
| 22-99 | Errata: minimum thickness for an NPS 30 weld-neck flange in Table 36 corrected to 149.4 mm. |
| 22-203 | Errata: Class 150 working pressure at 400 °C in Table 20 corrected to 5.5 bar. |
| 22-651 | Added a bolting material (A320-L7M) to Table 2. |
| 22-2110 | Revised ceiling pressures for Classes 300-900 in Table A-1 (A-1C). |
| 22-2277 | In the notes to Tables 3-6, 21 and 25, revised metric temperatures to the nearest degree. |
| 22-2279 | Added para. 1.13 defining 'may', 'shall' and 'should'; replaced 'must' with 'shall' in para. 2.2 and with 'should' in para. 5.3.5(a). |
| 23-2265 | Updated the references in Mandatory Appendix I. |
| 23-2374 | Revised materials in Table 1, and pressure values and notes in Tables 3-28 (3C-28C); added Table 29 (29C) for Group 2.13 materials. |
Scope is summarised from the record-number list; see the standard for the full text of each change.
Edition history at a glance
- Work on a large-diameter flange standard began in 1980. Early drafts covered NPS 26 to NPS 60 and Class 75 to Class 1500, with dimensions split into Series A (from MSS SP-44) and Series B (from API 605); Class 1500 was later dropped for lack of interest.
- ANSI approved the first edition on 12 June 1990. The 1996 edition added multiple material marking and permitted flange facing imperfections; the 2006 edition made metric units primary; the 2011 edition updated references; the 2017 edition revised Group 1.18 ratings at 650 °C.
- The 2020 edition moved the U.S. Customary tables from a mandatory appendix into the main text with a 'C' suffix (for example Table 3C), added bolt lengths to the dimension tables and added Nonmandatory Appendix D.
- The 2025 edition adds a bolting material, revises pressure–temperature ratings throughout, introduces the Group 2.13 duplex table, defines may/shall/should and updates the reference list.
ASME B16.47 edition changes — questions
Does B16.47-2025 replace B16.47-2020 or B16.47-2017?
It is the edition after B16.47-2020. The Foreword traces the sequence 2017, 2020, 2025, so a 2017 print is two editions old. Both the 2017 and 2020 prints predate the revised pressure–temperature ratings and the new Group 2.13 table, so re-check any rating taken from them.
Do the 2025 pressure–temperature ratings change my 2020 design?
They can. The Summary of Changes records revised pressure values and notes throughout Tables 3-28 (record 23-2374). The safe approach is to re-read the allowable pressure at the design temperature from the 2025 table for the exact material group, rather than carrying a 2020 or 2017 value across.
Which table covers duplex stainless flanges now?
Group 2.13 duplex and super-duplex grades are rated by the new Table 29 in bar and Table 29C in psig. The grades include A182 F51, F53, F55 and F60 forgings, A995 castings and A240 plate; check Table 1 to confirm which group your exact grade and product form falls into.
What does the margin note '(25)' mean?
It marks text changed in the 2025 edition. Where the standard shows '(25)' beside a clause, paragraph or table title, the change is traceable through the Summary of Changes and the record-number list. The same note is not used on unchanged text, so it functions as a compact change log in the body of the document.