ANSI Carbon Stainless Steel Flanges
Reference data and engineering information about ansi carbon stainless steel flanges for material properties applications.
Overview
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ASME/ANSI B16.5-1996 defines pipe flanges and flanged fittings for pressure classes ranging from 150 to 2500. The data below covers Class 600 flanges in carbon and stainless steel per ASME B16.5 Table 1A. Dimensions apply to weld neck, threaded, slip-on, lap joint, socket weld, and blind flange types.
ASME/ANSI B16.5-1996 Pipe Flanges and Flanged Fittings - Class 600 Flanges - outside and inside diameters, bolt circles, numbers and diameters of bolts for Weld neck, Threaded, Slip-on, Lap joint, Socket weld and Blind flanges.
Carbon and stainless steel qualities according ASME B16.5 Table 1A.
ASME/ANSI B16.5-1996 Pipe Flanges and Flanged Fittings - Class 600 Flanges
Outside and inside diameters, bolt circles, numbers and diameters of bolts are listed for Weld neck, Threaded, Slip-on, Lap joint, Socket weld and Blind flanges.
Key Formulas
Bolt Circle Diameter
For layout verification, the bolt circle (BC) relates to the flange outside diameter (OD) by the approximate relationship:
where is the bolt hole diameter and accounts for the flange ring thickness from the bolt hole center to the outer edge.
Bolt Hole Spacing
The angular spacing between bolt holes is:
where is the number of bolt holes.
Variables
| Symbol | Description | Typical Unit |
|---|---|---|
| Bolt circle diameter | inches | |
| Flange outside diameter | inches | |
| Nominal bolt hole diameter | inches | |
| Number of bolt holes | — | |
| Angular bolt spacing | degrees |
Flange Dimensions — Class 600
The table here is a normalized quick-reference view of the same Class 600 source dimensions. The complete original source table, including original fractional formatting, is preserved in the restored source table below.
- Recommended bolts are 1/8 smaller than the nominal bolt hole diameters shown.
Pipe Size (in) | Flange OD (in) | Pipe OD (in) | Bolt Holes | Bolt Hole Dia (in) | Bolt Circle (in) |
|---|---|---|---|---|---|
| 1/2 | 3.75 | 0.84 | 4 | 5/8 | 2-5/8 |
| 3/4 | 4.625 | 1.05 | 4 | 3/4 | 3-1/4 |
| 1 | 4.875 | 1.32 | 4 | 3/4 | 3-1/2 |
| 1-1/4 | 5.25 | 1.66 | 4 | 3/4 | 3-7/8 |
| 1-1/2 | 6.125 | 1.9 | 4 | 7/8 | 4-1/2 |
| 2 | 6.5 | 2.38 | 8 | 3/4 | 5 |
| 2-1/2 | 7.5 | 2.88 | 8 | 7/8 | 5-7/8 |
| 3 | 8.25 | 3.5 | 8 | 7/8 | 6-5/8 |
| 3-1/2 | 9 | 4 | 8 | 1 | 7-1/4 |
| 4 | 10.75 | 4.5 | 8 | 1 | 8-1/2 |
| 5 | 13 | 5.56 | 8 | 1-1/4 | 10-1/2 |
| 6 | 14 | 6.63 | 12 | 1-1/4 | 11-1/2 |
| 8 | 16.5 | 8.63 | 12 | 1-1/4 | 13-3/4 |
| 10 | 20 | 10.75 | 16 | 1-3/8 | 17 |
| 12 | 22 | 12.75 | 20 | 1-3/8 | 19-1/4 |
| 14 | 23.75 | 14 | 20 | 1-1/2 | 20-3/4 |
| 16 | 27 | 16 | 20 | 1-5/8 | 23-3/4 |
| 18 | 29.25 | 18 | 20 | 1-3/4 | 25-3/4 |
| 20 | 32 | 20 | 24 | 1-3/4 | 28-1/2 |
| 24 | 37 | 24 | 24 | 2 | 33 |
Source: engineeringtoolbox.com
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Unit Converter
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Restored Original Source Tables
The following tables are restored from the original source page to preserve the complete reference data.
Carbon and Stainless Steel Flanges - ASME/ANSI Class 600
Pipe Size (inches) | Flange Outside Diameter (inches) | Pipe Outside Diameter (inches) | Number of Bolt Holes | Bolt Hole Diameter (inches) 1) | Bolt Circle (inches) |
|---|---|---|---|---|---|
| 1/2 | 3-3/4 | 0.84 | 4 | 5/8 | 2-5/8 |
| 3/4 | 4-5/8 | 1.05 | 4 | 3/4 | 3-1/4 |
| 1 | 4-7/8 | 1.32 | 4 | 3/4 | 3-1/2 |
| 1-1/4 | 5-1/4 | 1.66 | 4 | 3/4 | 3-7/8 |
| 1-1/2 | 6-1/8 | 1.9 | 4 | 7/8 | 4-1/2 |
| 2 | 6-1/2 | 2.38 | 8 | 3/4 | 5 |
| 2-1/2 | 7-1/2 | 2.88 | 8 | 7/8 | 5-7/8 |
| 3 | 8-1/4 | 3.5 | 8 | 7/8 | 6-5/8 |
| 3-1/2 | 9 | 4 | 8 | 1 | 7-1/4 |
| 4 | 10-3/4 | 4.5 | 8 | 1 | 8-1/2 |
| 5 | 13 | 5.56 | 8 | 1-1/4 | 10-1/2 |
| 6 | 14 | 6.63 | 12 | 1-1/4 | 11-1/2 |
| 8 | 16-1/2 | 8.63 | 12 | 1-1/4 | 13-3/4 |
| 10 | 20 | 10.75 | 16 | 1-3/8 | 17 |
| 12 | 22 | 12.75 | 20 | 1-3/8 | 19-1/4 |
| 14 | 23-3/4 | 14 | 20 | 1-1/2 | 20-3/4 |
| 16 | 27 | 16 | 20 | 1-5/8 | 23-3/4 |
| 18 | 29-1/4 | 18 | 20 | 1-3/4 | 25-3/4 |
| 20 | 32 | 20 | 24 | 1-3/4 | 28-1/2 |
| 24 | 37 | 24 | 24 | 2 | 33 |
Source: engineeringtoolbox.com
Engineering Notes
- Recommended bolts are 1/8 smaller than the nominal bolt hole diameters shown.
1 inch = 25.4 mm.
- Bolt sizing: Recommended bolt diameter is 1/8 inch smaller than the nominal bolt hole diameter listed. This clearance allows for alignment during assembly while maintaining structural integrity.
- Material specification: Dimensions shown apply to both carbon steel and stainless steel flanges per ASME B16.5 Table 1A. Gasket seating surfaces and pressure-temperature ratings differ by material grade.
- Flange types: The same dimensional envelope (OD, bolt circle, bolt holes) applies to weld neck, slip-on, threaded, lap joint, socket weld, and blind flanges within a given nominal pipe size and class.
- Bolt count doubling: Note the jump from 4 to 8 bolt holes at the 2-inch size, and further increases at 6-inch and above. Higher bolt counts distribute sealing load more uniformly across larger gasket areas.
- Class selection: Class 600 is a mid-range pressure class. For the same pipe size, higher classes (900, 1500, 2500) use larger flanges, thicker bodies, and more or larger bolts.