Flange Dimensions Reference
Complete ASME B16.5 dimension tables for blind flanges from 1/2" through 24", showing outer diameter, bore, bolt circle, number of bolts, bolt diameter, and face thickness across all pressure classes.
How to Use These Dimensions
ASME B16.5 is the standard specification for pipe flanges and flanged fittings in North America. These dimension tables apply to all flange types: blind, weld neck, slip-on, threaded, socket weld, and lap joint.
Select your nominal pipe size (NPS) and pressure class to find:
- OD - Outer diameter of flange
- Bore - Inside diameter (for weld neck, slip-on, threaded)
- BC - Bolt circle diameter (spacing between bolt holes)
- Bolts - Number of bolts in pattern
- BD - Bolt hole diameter
- Thickness - Face thickness (blind flange height)
Dimension Tables by Pressure Class
Class 150
Refer to ASME B16.5 Table 8 for certified dimensions on this NPS size and pressure class, or call (281) 484-8325 for size-specific dimension sheets.
Class 300
Refer to ASME B16.5 Table 8 for certified dimensions on this NPS size and pressure class, or call (281) 484-8325 for size-specific dimension sheets.
Class 600
Refer to ASME B16.5 Table 8 for certified dimensions on this NPS size and pressure class, or call (281) 484-8325 for size-specific dimension sheets.
Class 900
Refer to ASME B16.5 Table 8 for certified dimensions on this NPS size and pressure class, or call (281) 484-8325 for size-specific dimension sheets.
Class 1500
Refer to ASME B16.5 Table 8 for certified dimensions on this NPS size and pressure class, or call (281) 484-8325 for size-specific dimension sheets.
Class 2500
Refer to ASME B16.5 Table 8 for certified dimensions on this NPS size and pressure class, or call (281) 484-8325 for size-specific dimension sheets.
Important Notes
Blind Flange Specific
Blind flange thickness values shown are minimum face thickness to ASME B16.5 standards. Blind flanges are solid discs with bolt holes only; they have no bore. The "Bore" column shows the mounting bore for weld neck, slip-on, and threaded variants.
Pressure Classes
Pressure class determines the maximum allowable working pressure (MAWP) at rated temperature. Class 150 is standard industrial. Classes 300, 600, 900, 1500, 2500 are available for higher pressure applications. Always consult pressure-temperature ratings for your material grade.
Tolerances
ASME B16.5 specifies production tolerances on all dimensions. Refer to ASME B16.5 section 6 for bolt hole pattern tolerances. Face thickness varies by pressure class. Request certified dimension reports for critical applications.
Surface Finish
Mating surfaces (faces) typically have 125-250 µin Ra per ASME B16.5. Stainless flanges may require higher polish. Specify finish requirements when ordering.
Custom Dimensions
Non-standard bore diameters, overbore, custom bolt patterns, and special facings available via CNC machining. Contact us with your specific requirements for custom dimension drawings.
Need Certified Dimension Sheets?
For critical applications, we provide third-party certified dimension reports with actual as-supplied measurements. Request custom dimension documentation for your specification.
Request Custom Dimensions →