The Complete Guide to ANSI Pipe Flange Dimensions
11.27.2025 |
A reference for ANSI flange dimensions across different pressure applications, this guide helps to select the right specifications for your project, including pipe sizes, bolt hole patterns, and bolt circle and flange diameters from 1/4 inch to 24 inches, along with guidance on referencing ANSI 125, 150, 300, and 600 flanges to ensure compatibility and reliable performance in pressurized systems.
Download the full ANSI Pipe Flange Dimensions PDF for all size references.
Jump to:
- ANSI 125 Flanges
- ANSI 150 Flanges
- ANSI 300 Flanges
- ANSI 600 Flanges
- How to Use ANSI Flange Dimensions for Your Project
- Related Resources
ANSI 125 Flanges (Cast-Iron)
If you need ANSI 125 flange dimensions for low-pressure piping applications. These flanges are widely used in HVAC, water systems, and general industrial service.
| Pipe Size (inches) | Outside Diameter (inches) | No. of Bolt Holes | Bolt Hole Diameter (inches) | Bolt Circle (inches) |
|---|---|---|---|---|
| 1 | 4‑1/4 | 4 | 5/8 | 3‑1/8 |
| 4 | 9 | 8 | 3/4 | 7‑1/2 |
| 8 | 13‑1/2 | 8 | 7/8 | 11‑3/4 |
ANSI 150 Flanges
Here are the standard ANSI 150 flange dimensions for steel pipe, including common sizes like 4 ANSI flange dimensions and 8 inch ANSI flange dimensions. This table is also useful as a flange dimensions ANSI 150 reference:
| Nominal Pipe Size (inches) | Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Bolt Circle (inches) |
|---|---|---|---|---|
| 1 | 4‑1/4 | 4 | 1/2 | 3‑1/8 |
| 4 | 9 | 8 | 5/8 | 7‑1/2 |
| 8 | 13‑1/2 | 8 | 3/4 | 11‑3/4 |
ANSI 300 Flanges
This table of ANSI 300 flange dimensions provides outside diameters, bolt patterns, and bolt-circle diameters for commonly used pipe sizes. ANSI 300 flanges are suitable for higher-pressure applications compared to the 150 class.
| Nominal Pipe Size (inches) | Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Bolt Circle (inches) |
|---|---|---|---|---|
| 1 | 4‑7/8 | 4 | 5/8 | 3‑1/2 |
| 4 | 10 | 8 | 7/8 | 7‑7/8 |
| 8 | 15 | 12 | 7/8 | 13 |
ANSI 600 Flanges
For high-pressure service, ANSI 600 flange dimensions ensure reliable system performance. The table below summarizes key metrics for selected sizes and is useful as a quick reference for 600 lb ANSI flanges.
| Nominal Pipe Size (inches) | Diameter of Flange (inches) | No. of Bolts | Diameter of Bolts (inches) | Bolt Circle (inches) |
|---|---|---|---|---|
| 4 | 10‑3/4 | 8 | 7/8 | 8‑1/2 |
| 8 | 16‑1/2 | 12 | 1‑1/8 | 13‑3/4 |
How to Use ANSI Flange Dimensions for Your Project
To correctly select and apply ANSI flange measurements, follow these steps:
-
Determine the nominal pipe size (NPS) and required pressure class.
- Refer to the relevant table to find the ANSI flange dimensions for bolt-hole pattern, bolt circle, and flange diameter.
- Ensure compatibility with mating components, valves, and blind flanges.
Accurate sizing ensures safe installation, prevents leakage, and maintains correct alignment in pressurized systems.
Related Resources
VF supplies a wide range of valves compatible with standard ANSI flange dimensions contact our support team or view all valves.