Flange bolt chart and bolt size chart
Stud bolt quantities, diameters and lengths for ASME B16.5 Class 150, 300, 600 and 900 flanges, with threads per inch and heavy hex nut wrench sizes.
Flange bolt chart: ASME B16.5 Class 150, 300, 600 and 900
Number of studs, stud diameter and stud length by nominal pipe size (NPS). RF / FF is raised face or flat face; RTJ is ring-type joint.
Class 150 flange stud bolts
| NPS | Studs | Dia. | RF / FF length | RTJ length |
|---|---|---|---|---|
| 1 | 4 | 1/2" | 2-1/2" | 3" |
| 1-1/2 | 4 | 1/2" | 2-3/4" | 3-1/4" |
| 2 | 4 | 5/8" | 3-1/4" | 3-3/4" |
| 3 | 4 | 5/8" | 3-1/2" | 4-1/4" |
| 4 | 8 | 5/8" | 3-1/2" | 4-1/4" |
| 6 | 8 | 3/4" | 4" | 4-1/2" |
| 8 | 8 | 3/4" | 4-1/4" | 4-3/4" |
| 10 | 12 | 7/8" | 4-3/4" | 5-1/4" |
| 12 | 12 | 7/8" | 4-3/4" | 5-1/2" |
| 14 | 12 | 1" | 5-1/4" | 6" |
| 16 | 16 | 1" | 5-1/2" | 6" |
| 18 | 16 | 1-1/8" | 6" | 6-1/2" |
| 20 | 20 | 1-1/8" | 6-1/2" | 7" |
| 24 | 20 | 1-1/4" | 7" | 7-3/4" |
Class 300 flange stud bolts
| NPS | Studs | Dia. | RF / FF length | RTJ length |
|---|---|---|---|---|
| 1 | 4 | 5/8" | 3" | 3-1/2" |
| 1-1/2 | 4 | 3/4" | 3-1/2" | 4" |
| 2 | 8 | 5/8" | 3-1/2" | 4" |
| 3 | 8 | 3/4" | 4-1/4" | 4-3/4" |
| 4 | 8 | 3/4" | 4-1/2" | 5" |
| 6 | 12 | 3/4" | 4-3/4" | 5-1/2" |
| 8 | 12 | 7/8" | 5-1/2" | 6" |
| 10 | 16 | 1" | 6-1/4" | 6-3/4" |
| 12 | 16 | 1-1/8" | 6-3/4" | 7-1/4" |
| 14 | 20 | 1-1/8" | 7" | 7-1/2" |
| 16 | 20 | 1-1/4" | 7-1/2" | 8" |
| 18 | 24 | 1-1/4" | 7-3/4" | 8-1/4" |
| 20 | 24 | 1-1/4" | 8-1/4" | 8-3/4" |
| 24 | 24 | 1-1/2" | 9-1/4" | 10" |
Class 600 flange stud bolts
| NPS | Studs | Dia. | RF / FF length | RTJ length |
|---|---|---|---|---|
| 1 | 4 | 5/8" | 3-1/2" | 3-1/2" |
| 1-1/2 | 4 | 3/4" | 4-1/4" | 4-1/4" |
| 2 | 8 | 5/8" | 4-1/4" | 4-1/2" |
| 3 | 8 | 3/4" | 5" | 5-1/4" |
| 4 | 8 | 7/8" | 5-3/4" | 6" |
| 6 | 12 | 1" | 6-3/4" | 7" |
| 8 | 12 | 1-1/8" | 7-3/4" | 8" |
| 10 | 16 | 1-1/4" | 8-1/2" | 8-3/4" |
| 12 | 20 | 1-1/4" | 8-3/4" | 9" |
| 14 | 20 | 1-3/8" | 9-1/4" | 9-1/2" |
| 16 | 20 | 1-1/2" | 10" | 10-1/4" |
| 18 | 20 | 1-5/8" | 10-3/4" | 11" |
| 20 | 24 | 1-5/8" | 11-1/2" | 11-3/4" |
| 24 | 24 | 1-7/8" | 13" | 13-1/2" |
Class 900 flange stud bolts
| NPS | Studs | Dia. | RF / FF length | RTJ length |
|---|---|---|---|---|
| 1 | 4 | 7/8" | 5" | 5" |
| 1-1/2 | 4 | 1" | 5-1/2" | 5-1/2" |
| 2 | 8 | 7/8" | 5-3/4" | 6" |
| 3 | 8 | 7/8" | 5-3/4" | 6" |
| 4 | 8 | 1-1/8" | 6-3/4" | 7" |
| 6 | 12 | 1-1/8" | 7-3/4" | 8" |
| 8 | 12 | 1-3/8" | 8-3/4" | 9" |
| 10 | 16 | 1-3/8" | 9-1/4" | 9-1/2" |
| 12 | 20 | 1-3/8" | 10" | 10-1/2" |
| 14 | 20 | 1-1/2" | 10-3/4" | 11-1/2" |
| 16 | 20 | 1-5/8" | 11-1/4" | 12" |
| 18 | 20 | 1-7/8" | 13" | 13-1/2" |
| 20 | 20 | 2" | 13-3/4" | 14-1/4" |
| 24 | 20 | 2-1/2" | 17-1/4" | 18" |
Stud counts and diameters per ASME B16.5, Pipe Flanges and Flanged Fittings. Lengths are measured first thread to first thread, without the points. Verify coating build-up and service conditions. Class 1500, Class 2500 and ASME B16.47 flanges are quoted on request.
Bolt thread chart: threads per inch
Unified inch threads for 1/4 in. through 4 in. A size is written diameter, then threads per inch: 3/4-10 is a 3/4 in. bolt with 10 threads per inch.
| Diameter | Coarse (UNC) | Fine (UNF) | 8-thread (8UN) |
|---|---|---|---|
| 1/4" | 20 | 28 | – |
| 5/16" | 18 | 24 | – |
| 3/8" | 16 | 24 | – |
| 7/16" | 14 | 20 | – |
| 1/2" | 13 | 20 | – |
| 9/16" | 12 | 18 | – |
| 5/8" | 11 | 18 | – |
| 3/4" | 10 | 16 | – |
| 7/8" | 9 | 14 | – |
| 1" | 8 | 12 | 8 |
| 1-1/8" | 7 | 12 | 8 |
| 1-1/4" | 7 | 12 | 8 |
| 1-3/8" | 6 | 12 | 8 |
| 1-1/2" | 6 | 12 | 8 |
| 1-5/8" | – | – | 8 |
| 1-3/4" | 5 | – | 8 |
| 1-7/8" | – | – | 8 |
| 2" | 4-1/2 | – | 8 |
| 2-1/4" | 4-1/2 | – | 8 |
| 2-1/2" | 4 | – | 8 |
| 2-3/4" | 4 | – | 8 |
| 3" | 4 | – | 8 |
| 3-1/4" | 4 | – | 8 |
| 3-1/2" | 4 | – | 8 |
| 3-3/4" | 4 | – | 8 |
| 4" | 4 | – | 8 |
Source: ASME B1.1, Unified Inch Screw Threads. A dash means the series has no standard size at that diameter. Above 1 in., studs for flange and pressure service are normally ordered in the 8-thread series.
Heavy hex nut size chart
Width across flats is the wrench size. Heavy hex nuts, including A194 2H, are the nuts used on stud bolts.
| Bolt diameter | Width across flats (wrench size) | Nut thickness |
|---|---|---|
| 1/2" | 7/8" | 31/64" |
| 5/8" | 1-1/16" | 39/64" |
| 3/4" | 1-1/4" | 47/64" |
| 7/8" | 1-7/16" | 55/64" |
| 1" | 1-5/8" | 63/64" |
| 1-1/8" | 1-13/16" | 1-7/64" |
| 1-1/4" | 2" | 1-7/32" |
| 1-3/8" | 2-3/16" | 1-11/32" |
| 1-1/2" | 2-3/8" | 1-15/32" |
| 1-5/8" | 2-9/16" | 1-19/32" |
| 1-3/4" | 2-3/4" | 1-23/32" |
| 1-7/8" | 2-15/16" | 1-27/32" |
| 2" | 3-1/8" | 1-31/32" |
| 2-1/4" | 3-1/2" | 2-13/64" |
| 2-1/2" | 3-7/8" | 2-29/64" |
| 2-3/4" | 4-1/4" | 2-45/64" |
| 3" | 4-5/8" | 2-61/64" |
| 3-1/4" | 5" | 3-3/16" |
| 3-1/2" | 5-3/8" | 3-7/16" |
| 3-3/4" | 5-3/4" | 3-11/16" |
| 4" | 6-1/8" | 3-15/16" |
Source: ASME B18.2.2, heavy hex nuts, basic dimensions. Tolerances are given in the standard.
How to read and measure a bolt size
Diameter
The nominal diameter is measured across the outside of the threads. A 3/4 in. stud measures just under 3/4 in. over the thread crests.
Threads per inch
Count the thread crests in one inch of length, or use a thread pitch gauge. Match the count to the chart above to find the series.
Stud length
Flange studs are conventionally measured first thread to first thread, without the points. Headed bolts are measured from under the head to the end.
Nut size
Measure across two opposite flats. That is the wrench size shown in the heavy hex nut chart.
Order from the chart
Cyclone manufactures and supplies stud bolts from 1/4 in. through 4 in. in diameter, with heavy hex nuts and the finish you specify. Send the flange class, pipe size, quantity and specification and the team will quote it.