A U-bolt is measured by four dimensions: the length, the hook, the diameter, and the thread length. In waterworks applications, you can refer to the chart below for the correct U-bolt size you will need for different pipe sizes.
The length of a U-bolt is measured from the end of the bolt to the inside of the bend (see image above).U-Bolt Hook
A U-bolt’s hook is the distance between the legs of the bolt, as represented by “C” in the image above. It’s important to note that in some drawings, the hook is shown at the center or bottom of the bolt. Furthermore, some companies measure the hook from the center of one leg to the center of the other leg. Birmingham Fastener measures the dimensions as outlined in the Industrial Fastener Institute Standard IFI-136.
To measure a U-bolt’s diameter, you’ll measure the diameter of one of the bolt’s legs (see “D” in the image above).
This chart is available for referencing U-bolt lengths. All sizes are in inches. For a printable version of our chart, download our U-Bolt Length Chart PDF.
| Pipe Size | Diameter | C (Hook) | L (Length) | T (Thread Length) |
|---|---|---|---|---|
| 1/2 | 1/4 | 15/16 | 3 1/4 | 2 3/8 |
| 3/4 | 1/4 | 1 1/8 | 3 5/16 | 2 3/8 |
| 1 | 1/4 | 1 3/8 | 3 7/16 | 2 3/8 |
| 1 1/4 | 3/8 | 1 11/16 | 3 3/4 | 2 3/8 |
| 1 1/2 | 3/8 | 2 | 4 | 2 1/2 |
| 2 | 3/8 | 2 7/16 | 4 1/2 | 2 1/2 |
| 2 1/2 | 1/2 | 2 15/16 | 5 1/4 | 3 |
| 3 | 1/2 | 3 9/16 | 5 13/16 | 3 |
| 3 1/2 | 1/2 | 4 1/16 | 6 5/16 | 3 |
| 4 | 1/2 | 4 9/16 | 6 13/16 | 3 |
| 5 | 1/2 | 5 5/8 | 7 13/16 | 3 |
| 6 | 5/8 | 6 3/4 | 9 1/2 | 3 3/4 |
| 8 | 5/8 | 8 3/4 | 11 1/2 | 3 3/4 |
| 10 | 3/4 | 10 7/8 | 13 13/16 | 4 |
| 12 | 7/8 | 12 7/8 | 16 1/16 | 4 1/4 |
| 14 | 7/8 | 14 1/8 | 17 5/16 | 4 1/4 |
| 16 | 7/8 | 16 1/8 | 19 5/16 | 4 1/4 |
| 18 | 1 | 18 1/8 | 21 11/16 | 4 3/4 |
| 20 | 1 | 20 1/8 | 23 11/16 | 4 3/4 |
| 24 | 1 | 24 1/8 | 27 11/16 | 4 3/4 |
| 30 | 1 | 30 1/8 | 33 11/16 | 4 3/4 |
| 36 | 1 | 36 1/8 | 39 11/16 | 4 3/4 |