ASME B16.47 Series A flanges are large-diameter weld neck and blind flanges from NPS 26" to NPS 60" in Class 150, 300, 400, 600 and 900. Series A takes its dimensions from the former MSS SP-44 standard: heavy, thick flanges with fewer, larger bolts, widely used on pipelines, oil and gas facilities and large cooling and firewater mains.
Raaj Fittings forges and machines B16.47 Series A flanges in carbon, low-temperature and alloy steel, stainless steel and duplex at our two plants in India, for EPC contractors and pipeline projects across the Middle East, Europe and the Americas.
| Series A (MSS SP-44) | Series B (API 605) | |
|---|---|---|
| Classes | 150, 300, 400, 600, 900 | 75, 150, 300, 400, 600, 900 |
| Construction | Heavier, thicker flanges | Lighter, more compact flanges |
| Bolting | Fewer, larger bolts | More, smaller bolts |
| Typical use | Pipelines, oil and gas, general heavy-duty service | Refinery and process piping, mating with compact equipment |
Always check which series the mating flange, valve or equipment nozzle uses: a Series A flange will not bolt to a Series B flange of the same size and class.
Series A flanges are supplied with raised face or ring type joint facings, and weld neck flanges are bored to match the pipe wall and bevelled to ASME B16.25. Blind flanges in large sizes are heavy forgings, so lifting lugs or tapped holes can be specified.
Every B16.47 flange is made from PMI-verified material, dimensionally inspected against the ordered standard and marked with material, size, rating and heat number. Orders are supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request.
Yes. MSS SP-44 dimensions were adopted as ASME B16.47 Series A. Older drawings may still specify MSS SP-44; Series A flanges match them.
No. They have different outside diameters, bolt circles and bolting for the same size and class, so they are not interchangeable.
NPS 26" to 60". Flanges up to 24" are covered by ASME B16.5.
No, ASME B16.47 covers weld neck and blind flanges only. Other large-diameter flange types are made to project drawings or other standards.