1. Size Range & Classification
Coverage: NPS 26" to 60" (DN 650 to DN 1500)
Two Series:
Series A (MSS SP-44): Heavy-wall construction
Series B (API 605): Lighter-weight design
Pressure Classes: 75, 150, 300, 400, 600, 900
2. Critical Dimensional Parameters
For a NPS 36" Class 150 Flange:
| Dimension | Series A | Series B | Tolerance |
|---|---|---|---|
| Outside Diameter (OD) | 52.50" | 50.50" | ±0.25" |
| Thickness (T) | 2.25" | 1.88" | +0.06/-0.03" |
| Bolt Circle (BC) | 49.50" | 47.50" | ±0.06" |
| Hub Diameter (X) | 38.25" | 37.63" | ±0.03" |
| # of Bolt Holes | 56 | 44 | - |
| Bolt Size | 1-1/4" | 1-1/8" | - |
3. Face Configuration Standards
Raised Face (RF):
Height: 0.06" (1.6mm) for NPS 26-36"
Height: 0.25" (6.4mm) for NPS 38-60"
Ring-Type Joint (RTJ):
Groove dimensions per ASME B16.5
R37, R38, or RX profiles available
4. Weight Comparison
| NPS | Class | Series A Weight | Series B Weight |
|---|---|---|---|
| 30" | 300 | 1,850 lbs | 1,450 lbs |
| 48" | 150 | 3,200 lbs | 2,600 lbs |
| 60" | 600 | 8,500 lbs | N/A (Series A only) |
5. Manufacturing Tolerances
Bore Diameter: ±1% of nominal size
Flange Flatness: 0.03" across any diameter
Bolt Hole Alignment: ±1° angular deviation
Surface Finish: 125-250 µin Ra for RF faces
6. Installation Considerations
Bolt Torque Requirements:
Series A typically requires 30-40% higher torque than Series B
Example: NPS 36" Class 300:
Series A: 2,800 ft-lbs
Series B: 2,100 ft-lbs
Gasket Selection:
Full-face gaskets required for Series B
Ring gaskets standard for Series A
Handling Requirements:
48" flanges often require special lifting lugs
Field rotation adjustment limited to ±5°
7. Industry Applications
Series A Preferred For:
High-pressure gas transmission (ANSI 900#)
Refinery critical service
Subsea applications
Series B Typical Uses:
Water treatment plants
Low-pressure hydrocarbon service
Retrofit projects replacing API 605 flanges
8. Dimensional Checklist for Engineers
When specifying B16.47 flanges, always verify:
Series designation (A or B)
Complete bolt hole pattern
Hub taper dimensions
Facing finish requirements
Nozzle weld prep details (for WN flanges)
Non-destructive examination (NDE) requirements
This dimensional data should be cross-referenced with the latest ASME B16.47 standard, as tolerances and manufacturing requirements are periodically updated. For critical applications, always request certified dimensional drawings from the manufacturer.
