ASME B16.47
Large-diameter steel flanges, NPS 26 through NPS 60
Covers large-diameter steel flanges from NPS 26 to NPS 60 in two series — Series A (heavier, from the old MSS SP-44) and Series B (compact, from API 605).
- Dimensional standards
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASME B16.47?
ASME B16.47 is the standard for large-diameter steel flanges, NPS 26 to NPS 60. It has two series that are not interchangeable: Series A, based on MSS SP-44, with heavier flanges and larger bolts, and Series B, based on API 605, more compact. Smaller sizes are in ASME B16.5.
ASME B16.47 at a glance
| Sizes | NPS 26 – 60 |
|---|---|
| Series A | Based on MSS SP-44 — Classes 150 to 900 |
| Series B | Based on API 605 — Classes 75 to 900, more compact |
| Material | Named separately (A182, A105, A350, B564) |
Series A vs Series B
| Series A | Series B | |
|---|---|---|
| Origin | MSS SP-44 | API 605 |
| Flange size | Heavier, larger bolt circle | Lighter, smaller OD |
| Classes | 150 – 900 | 75 – 900 |
| Interchangeable? | No — bolt patterns differ | No |
How to write ASME B16.47 on a purchase order
Name the product, size, material specification and grade, the dimensional standard and the certificate. An example line:
Illustrative only — sizes, tests, inspection level and any project values come from your purchase specification.
ASME B16.47 edition and verification status
Which edition we have confirmed, and what is still being checked before any numerical requirement is published here.
| Current edition | Not yet confirmed against the publisher listing |
|---|---|
| Full-text verification | In progress — numerical requirements are not published on this page |
| Edition on your order | The edition named in your purchase order or design code governs — confirm it with your enquiry |
What to know before ordering to ASME B16.47
The points that decide whether material to ASME B16.47 is accepted at inspection.
- Series A and Series B flanges do not bolt to each other; specify the series.
- Material is ordered to A182, A105 or B564 as usual.
- Classes run from 75 (Series B) to 900.
Products made to ASME B16.47
How ASME B16.47 fits into an order
A purchase order line is only complete when it names the material standard, the dimensional standard and the inspection document. Miss one and the mill, the inspector and the buyer can each read the order differently.
Standards used with ASME B16.47
Same family
ASME B16.47 — questions buyers ask
What is ASME B16.47?
ASME B16.47 is the standard for large-diameter steel flanges, NPS 26 to NPS 60. It has two series that are not interchangeable: Series A, based on MSS SP-44, with heavier flanges and larger bolts, and Series B, based on API 605, more compact. Smaller sizes are in ASME B16.5.
Are B16.47 Series A and Series B interchangeable?
No. The outside diameters and bolt patterns differ, so the mating flange must be the same series.
Which series should I order?
The one your piping class or equipment nozzle specifies. Series A is common on process piping; Series B on some equipment and pipeline projects.
Does ASME B16.47 specify the material?
No. ASME B16.47 sets dimensions and pressure-temperature ratings; the material comes from a separate specification such as ASTM A182, A105 or B564 for flanges, or A403 and B366 for fittings. A complete order names both.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026