What is ASME B16.47?
ASME B16.47 is the American dimensional standard for large-diameter steel pipe flanges from NPS 26 inch to NPS 60 inch. It exists in two independent series, A and B, which are not interchangeable with each other.
Key Takeaways
- ASME B16.47 scope: Weld neck and blind flanges in the large-diameter range, with the bolt circle, thickness, hub geometry, facing dimensions and pressure-temperature ratings fixed for each size and class.
- Size range: NPS 26 inch to NPS 60 inch.
- Ratings: Class 75, 150, 300, 400, 600 and 900.
- Material grades: ASTM A105 and A350 LF2 carbon steel, A182 F304L / F316L / F11 / F22 / F51, and B564 nickel alloys.
- Kalp Alloys manufactures to ASME B16.47 in Ahmedabad, India, with EN 10204 3.1 and 3.2 certification issued in its own name.
- Third-party inspection by SGS, BV, TUV or Lloyds can be witnessed at our plant before dispatch.
What ASME B16.47 governs
ASME B16.47 is the American dimensional standard for large-diameter steel pipe flanges from NPS 26 inch to NPS 60 inch. It exists in two independent series, A and B, which are not interchangeable with each other.
Weld neck and blind flanges in the large-diameter range, with the bolt circle, thickness, hub geometry, facing dimensions and pressure-temperature ratings fixed for each size and class.
Scope, sizes and ratings at a glance
The envelope below is the practical reference: what to state on a purchase order so the item that arrives is the item the line needs.
| Parameter | Detail |
|---|---|
| Size range | NPS 26 inch to NPS 60 inch |
| Ratings | Class 75, 150, 300, 400, 600 and 900 |
| Material grades | ASTM A105 and A350 LF2 carbon steel, A182 F304L / F316L / F11 / F22 / F51, and B564 nickel alloys |
| Size range | NPS 26 inch to 60 inch |
| Series A predecessor | MSS SP-44 |
| Series B predecessor | API 605 |
| Series A characteristics | Heavier, larger outside diameter and bolt circle, fewer larger bolts |
| Series B characteristics | Lighter and more compact, smaller bolt circle, more but smaller bolts |
| Interchangeable | No — Series A and Series B never mate with each other |
| Below NPS 26 inch | Governed by ASME B16.5 instead |
The point buyers most often get wrong
The single most costly error with B16.47 is treating the two series as equivalent. Series A descends from MSS SP-44 and is heavier with a larger bolt circle; Series B descends from API 605 and is more compact with a smaller bolt circle and more bolts. A Series A flange will not mate with a Series B flange of the same size and class, so the series must be stated on the purchase order and confirmed against the counter-flange already installed.
What Kalp Alloys manufactures to ASME B16.47
Kalp Alloys is a manufacturer, not a stockist. Production runs at our own facility at 5, Jay Vijay Industrial Estate, B/h. Akash Vikas Estate, Keval Kanta Road, Rakhial, Ahmedabad, which means the heat number stamped on the part traces to our own melt record and the mill test certificate is issued in the name of Kalp Alloys.
That matters on standard-led purchasing more than anywhere else, because an approved-vendor submission or a code-governed line has to show who made the part. A certificate passed down a trading chain names a mill the buyer has no relationship with and cannot query.
Grades supplied against ASME B16.47 cover ASTM A105 and A350 LF2 carbon steel, A182 F304L / F316L / F11 / F22 / F51, and B564 nickel alloys. Non-standard bores, thicknesses, drilling patterns and facing finishes are produced to customer drawing.
Ordering against ASME B16.47
State the dimensional standard, the size or NPS range, the rating or schedule, the facing where applicable, the material specification and grade, the quantity, and the certification level required. A quotation is typically returned within 24 hours.
Drawings for non-standard items can be sent by email or on WhatsApp at +91 81608 73937 and are reviewed by the technical team. Stock sizes dispatch in three to seven days; made-to-drawing items carry a firm lead time quoted at order confirmation. There is no minimum order on stock sizes and trial quantities are accepted.
Frequently Asked Questions
ASME B16.47 is the American dimensional standard for large-diameter steel pipe flanges from NPS 26 inch to NPS 60 inch. It exists in two independent series, A and B, which are not interchangeable with each other.
NPS 26 inch to NPS 60 inch. Ratings covered are Class 75, 150, 300, 400, 600 and 900.
ASTM A105 and A350 LF2 carbon steel, A182 F304L / F316L / F11 / F22 / F51, and B564 nickel alloys.
Whichever series the project specification names, or whichever matches the counter-flange already installed. If neither is documented, measure the bolt circle diameter and bolt count on the existing flange, because that is what distinguishes the two series in the field.
Sizes beyond the standard range are produced to customer drawing rather than to B16.47, with dimensions and ratings agreed in writing before manufacture.
Yes. Kalp Alloys manufactures to ASME B16.47 at its own facility at 5, Jay Vijay Industrial Estate, B/h. Akash Vikas Estate, Keval Kanta Road, Rakhial, Ahmedabad, and issues the EN 10204 3.1 or 3.2 mill test certificate in its own name rather than passing through a third-party mill certificate.
An EN 10204 3.1 mill test certificate as standard, stating the ordered standard, grade and heat number, with chemical and mechanical results and a dimensional inspection report. EN 10204 3.2 with third-party inspection by SGS, BV, TUV or Lloyds is arranged where the project requires it.