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Flange Bolt Dimensions Chart for Class 150 to 2500 Flanges
When selecting flanges for a piping system, bolt dimensions are just as critical as the flange itself. The size, number, and length of bolts or studs depend on the flange class and nominal pipe size (NPS). Proper selection ensures leak-free operation and long-term safety.
Below is a full chart of flange bolt dimensions for Class 150, 300, 600, 900, 1500, and 2500 standards, commonly used in oil & gas, chemical, water treatment, and food-grade industries.
Class 150 Flange Bolt Dimensions
| NPS | Number of Bolts | Bolt Diameter (in) | Bolt Length (in) |
|---|---|---|---|
| 1/2″ | 4 | 1/2″ | 2.00 |
| 3/4″ | 4 | 1/2″ | 2.25 |
| 1″ | 4 | 1/2″ | 2.50 |
| 2″ | 4 | 5/8″ | 3.00 |
| 3″ | 4 | 5/8″ | 3.25 |
| 4″ | 8 | 5/8″ | 3.50 |
| 6″ | 8 | 3/4″ | 3.75 |
| 8″ | 8 | 3/4″ | 4.00 |
| 10″ | 12 | 7/8″ | 4.50 |
| 12″ | 12 | 7/8″ | 4.75 |
Class 600 Flange Bolt Dimensions
| NPS | Number of Bolts | Stud Diameter (in) | Stud Length (in) |
|---|---|---|---|
| 1/2″ | 4 | 5/8″ | 3.50 |
| 1″ | 4 | 5/8″ | 4.25 |
| 2″ | 8 | 3/4″ | 4.75 |
| 3″ | 8 | 7/8″ | 5.25 |
| 4″ | 8 | 7/8″ | 5.50 |
| 6″ | 12 | 1″ | 6.00 |
| 8″ | 12 | 1-1/8″ | 6.50 |
| 10″ | 16 | 1-1/4″ | 7.00 |
| 12″ | 20 | 1-1/4″ | 7.50 |
Class 900 Flange Stud Chart
| NPS | Number of Studs | Stud Diameter (in) | Stud Length (in) |
|---|---|---|---|
| 1″ | 4 | 3/4″ | 4.50 |
| 2″ | 8 | 7/8″ | 5.00 |
| 3″ | 8 | 1″ | 5.50 |
| 4″ | 8 | 1″ | 6.00 |
| 6″ | 12 | 1-1/8″ | 6.75 |
| 8″ | 12 | 1-1/4″ | 7.50 |
| 10″ | 16 | 1-1/2″ | 8.25 |
| 12″ | 20 | 1-1/2″ | 9.00 |
Class 1500 Bolt Dimensions
| NPS | Number of Studs | Stud Diameter (in) | Stud Length (in) |
|---|---|---|---|
| 1″ | 4 | 7/8″ | 5.00 |
| 2″ | 8 | 1″ | 6.00 |
| 3″ | 8 | 1-1/8″ | 6.75 |
| 4″ | 8 | 1-1/4″ | 7.50 |
| 6″ | 12 | 1-1/2″ | 8.50 |
| 8″ | 12 | 1-3/4″ | 9.50 |
| 10″ | 16 | 2″ | 10.50 |
| 12″ | 20 | 2″ | 11.25 |
Class 2500 Stud & Bolt Dimensions
| NPS | Number of Studs | Stud Diameter (in) | Stud Length (in) |
|---|---|---|---|
| 1″ | 4 | 1″ | 6.25 |
| 2″ | 8 | 1-1/4″ | 7.00 |
| 3″ | 8 | 1-3/8″ | 8.00 |
| 4″ | 8 | 1-1/2″ | 9.00 |
| 6″ | 12 | 2″ | 10.50 |
| 8″ | 12 | 2-1/4″ | 12.00 |
| 10″ | 16 | 2-1/2″ | 13.50 |
Notes on Flange Bolt Sizing
- Stud bolts are often used with flanges due to their ease of installation and superior strength.
- Lengths listed above are based on standard raised face flanges. For RTJ (Ring Type Joint) or lap joint flanges, bolt length may vary.
- Always ensure compatibility with flange face type and gasket thickness.
Explore Related Technical Resources
To further support your flange and piping projects, you may find these helpful:
- Learn about Stainless Steel Flanges for hygienic and industrial use cases.
- Understand connection types by reading our guide on Buttweld Pipe Fittings.
- Explore Sanitary Pipe Fittings commonly used in dairy and pharmaceutical industries.
- Discover pressure-specific weights in our Flange Weight Calculator.
Note: The above links are shared for educational reference. We are not promoting any brand or product.
Request a Custom Flange Bolt Chart
Looking for a downloadable Excel or PDF flange bolt chart specific to your project? We offer custom bolt and gasket sizing tables for fabrication and installation teams. Contact our team via the Mahadev Dairy Pharma Fittings Contact Page.
