ASME B16.47 covers large diameter steel flanges from NPS 26" to NPS 60" in pressure classes 150 to 900. Two series are included — Series A (derived from MSS SP-44) and Series B (derived from API 605) — and they are NOT interchangeable. Always specify which series is required. Arshya Pipe Fittings supplies ASME B16.47 flanges in all materials with EN 10204 3.1 or 3.2 certification.
Request ASME B16.47 Flange QuoteASME B16.47 Series A and Series B have different bolt hole patterns, bolt circle diameters, and flange thicknesses at the same nominal size and pressure class. A Series A flange will NOT bolt up to a Series B flange of the same NPS and class. Always confirm which series is installed at the mating equipment and specify the same series for replacement or new-build flanges. Mixing Series A and Series B on a single flange joint is an unsafe engineering error.
| Property | Series A (MSS SP-44) | Series B (API 605) |
|---|---|---|
| Origin | MSS SP-44 — Manufacturers Standardisation Society | API 605 (withdrawn; superseded by B16.47 Series B) |
| Primary industry | Refineries, chemical plants, general process piping | Pipeline, gas transmission, pipeline compression stations |
| Flange weight | Heavier — larger bolt circle, more material | Lighter — smaller bolt circle, less material |
| Bolt circle diameter | Larger at same NPS and class | Smaller at same NPS and class — NOT interchangeable |
| Pressure classes | 150, 300, 400, 600, 900 | 150, 300, 400, 600, 900 |
| NPS range | NPS 26" to NPS 60" | NPS 26" to NPS 60" |
| Interchangeability with B16.5 | Matches B16.5 bolt circle at NPS 24" transition | Different at transition — check before mixing |
| Interchangeability A vs B | Series A and Series B are NOT interchangeable — different bolt patterns at same NPS and class | |
ASME B16.47 covers NPS 26"–60" flanges in two series. Series A derived from MSS SP-44 — used in general process piping, refineries, and chemical plants. Series A flanges are heavier with larger bolt circles. Series B derived from API 605 (now withdrawn) — used primarily in pipeline and gas transmission service. Series B flanges are lighter with smaller bolt circles. Series A and Series B are NOT interchangeable — different bolt hole patterns and bolt circle diameters at the same class and NPS. Always specify Series A or Series B. Mismatching on a flange joint is a serious safety error.
ASME B16.5 covers pipe flanges from NPS ½" through NPS 24". ASME B16.47 covers NPS 26" through NPS 60". For NPS 26" and above, B16.47 Series A or Series B applies. At the transition NPS 24"/26": B16.5 stops at NPS 24"; B16.47 starts at NPS 26". At the transition point on a piping system, verify bolt circle compatibility between the last B16.5 NPS 24" flange and the first B16.47 NPS 26" Series A flange — they are typically designed to be compatible in Series A, but confirm dimensionally. Series B at NPS 26" may have a different bolt circle from B16.5 NPS 24" — always check the specific project specification.
