Bolting up a pair of flanges? This tells you how many stud bolts the joint takes, what diameter they are, a typical length, and how many nuts to grab. Pick the pressure class, find your pipe size, and you’ve got your count — handy for pulling a job or checking a count before you head out.
Nuts = two per stud. Flange stud bolts are threaded both ends and take a heavy hex nut on each — so a joint needs the stud count × 2 in nuts. The chart does that math for you in the last column.
| Pipe size (NPS) | Stud bolts | Stud dia. | Nuts (2 / stud) | Typical length |
|---|---|---|---|---|
| ½″ | 4 | ½″ | 8 | 2½″ |
| ¾″ | 4 | ½″ | 8 | 2¾″ |
| 1″ | 4 | ½″ | 8 | 3″ |
| 1½″ | 4 | ½″ | 8 | 3¼″ |
| 2″ | 4 | ⅝″ | 8 | 3½″ |
| 3″ | 4 | ⅝″ | 8 | 3¾″ |
| 4″ | 8 | ⅝″ | 16 | 4″ |
| 6″ | 8 | ¾″ | 16 | 4¼″ |
| 8″ | 8 | ¾″ | 16 | 4½″ |
| 10″ | 12 | ⅞″ | 24 | 5″ |
| 12″ | 12 | ⅞″ | 24 | 5¼″ |
| 14″ | 12 | 1″ | 24 | 5¾″ |
| 16″ | 16 | 1″ | 32 | 6″ |
| 18″ | 16 | 1⅛″ | 32 | 6¾″ |
| 20″ | 20 | 1⅛″ | 40 | 7″ |
| 24″ | 20 | 1¼″ | 40 | 8″ |
One flanged joint = two flanges bolted together. The stud count is the number of bolt holes the flange has; you run one stud through each, with a nut on both ends. So a 6″ Class 150 joint takes 8 studs and 16 nuts.
Higher pressure classes (600, 900, 1500, 2500) use more and larger studs — we stock them, but the counts and lengths differ from what’s shown here. Bring us the flange class and size and we’ll pull the right studs and nuts.
Need the studs themselves? We cut stud bolt and all-thread to length and carry the matching B7 studs and 2H nuts — just give us the joint. Not sure how to measure a flange’s pipe size? See the note on pipe sizing.
