A pipe union is a secure and semi-permanent connection between two pipes. Most pipe unions consist of two pipes connected together via a third piece. All three are threaded to make a firm connection. While unions are similar to couplings, they are generally easier to take apart and allow pipes of different metals to come together safely. This joining method is common in household and commercial pipe systems.
| NPS | A(Pipe End) | C(Wall) | D1(Water Way Bore) | D2(Water Way Bore) | F(Male Flange) | G(Nut) | H(Threads) | J(Bearing) | L(Length) | N |
| 1/8″ | 14.7 | 2.41 | 8.43 | 6.43 | 3.18 | 3.18 | 16 | 1.24 | 41.4 | 50.8 |
| 1/4″ | 19 | 3.02 | 11.13 | 9.45 | 3.18 | 3.18 | 16 | 1.24 | 41.4 | 50.8 |
| 3/8″ | 22.9 | 3.2 | 14.27 | 13.51 | 3.43 | 3.43 | 14 | 1.37 | 46 | 55.9 |
| 1/2″ | 27.7 | 3.73 | 17.86 | 17.07 | 3.68 | 3.68 | 14 | 1.5 | 49 | 58.4 |
| 3/4″ | 33.5 | 3.91 | 23.01 | 21.39 | 4.06 | 4.06 | 11 | 1.68 | 56.9 | 66 |
| 1″ | 41.4 | 4.55 | 28.98 | 27.74 | 4.57 | 4.45 | 11 | 1.85 | 62 | 78.7 |
| 1-1/4″ | 50.5 | 4.85 | 37.69 | 35.36 | 5.33 | 5.21 | 11 | 2.13 | 71.1 | 94 |
| 1-1/2″ | 57.2 | 5.08 | 43.54 | 41.2 | 5.84 | 5.59 | 10 | 2.31 | 76.5 | 111.8 |
| 2″ | 70.1 | 5.54 | 55.58 | 52.12 | 6.6 | 6.35 | 10 | 2.69 | 86.1 | 132.1 |
| 2-1/2″ | 85.3 | 7.01 | 66.27 | 64.31 | 7.49 | 7.11 | 8 | 3.07 | 102.4 | 149.9 |
| 3″ | 102.4 | 7.62 | 88.25 | 77.27 | 8.26 | 8 | 8 | 3.53 | 109 | 175.3 |
