The Complete Guide to ANSI Pipe Flange Dimensions
11.27.2025 |
Overview
This guide provides a comprehensive reference for ANSI flange dimensions. It covers standard pipe sizes from 1/4" to 24" and includes bolt-hole patterns, bolt-circle diameters, and flange outside diameters. 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.