Dimension table · Flanges
ASME B16.5 flange dimensions: Class 150 to Class 2500
Bolt circle W, outside diameter O, raised-face diameter R and the number and diameter of holes Z × I (catalogue letters of the ASME world), plus pipe outside diameter and stud size – in separate tables per pressure class from Class 150 to Class 2500, nominal sizes in inches from 1/2" to 24". These flanges are still commercially known as “ANSI flanges” or “150/300/600 lbs” – but the class number is not a pressure rating in psi or pounds. Unlike EN 1092-1, ASME flanges are not part of the scope of the European standard – always check which standard is required on international projects.
Hole diameter I ≠ bolt diameter: I is the bolt hole in the flange plate – the matching bolt is always thinner (clearance for assembly and alignment). Example: 19.1 mm hole → 3/4″ bolt, i.e. M16/UNC 3/4. The bolt size follows from the standard, not from the hole dimension.
Class 150 – connection dimensions (1/2"–24")
Show full table · more than 10 rows
| NPS | Pipe OD (mm) 1 | Z × ØI – holes (mm) | Stud – bolts 2 | ØR – Raised Face (mm) | ØW – bolt circle (mm) | ØO – outside (mm) |
|---|---|---|---|---|---|---|
| 1/2" | 21.3 | 4 × 15.7 | 1/2" | 35.1 | 60.5 | 88.9 |
| 3/4" | 26.7 | 4 × 15.7 | 1/2" | 42.9 | 69.9 | 98.6 |
| 1" | 33.4 | 4 × 15.7 | 1/2" | 50.8 | 79.2 | 108 |
| 1 1/4" | 42.2 | 4 × 15.7 | 1/2" | 63.5 | 88.9 | 117.3 |
| 1 1/2" | 48.3 | 4 × 15.7 | 1/2" | 73.2 | 98.6 | 127 |
| 2" | 60.3 | 4 × 19.1 | 5/8" | 91.9 | 120.7 | 152.4 |
| 3" | 88.9 | 4 × 19.1 | 5/8" | 127 | 152.4 | 190.5 |
| 4" | 114.3 | 8 × 19.1 | 5/8" | 157.2 | 190.5 | 228.6 |
| 5" | 141.3 | 8 × 22.4 | 3/4" | 185.7 | 215.9 | 254 |
| 6" | 168.3 | 8 × 22.4 | 3/4" | 215.9 | 241.3 | 279.4 |
| 8" | 219.1 | 8 × 22.4 | 3/4" | 269.7 | 298.5 | 342.9 |
| 10" | 273.1 | 12 × 25.4 | 7/8" | 323.9 | 362 | 406.4 |
| 12" | 323.9 | 12 × 25.4 | 7/8" | 381 | 431.8 | 482.6 |
| 14" | 355.6 | 12 × 28.4 | 1" | 412.8 | 476.3 | 533.4 |
| 16" | 406.4 | 16 × 28.4 | 1" | 469.9 | 539.8 | 596.9 |
| 18" | 457.2 | 16 × 31.8 | 1 1/8" | 533.4 | 577.9 | 635 |
| 20" | 508.0 | 20 × 31.8 | 1 1/8" | 584.2 | 635 | 698.5 |
| 22" 3 | 558.8 | 20 × 35.1 | 1 1/4" | – | 692.1 | 749.3 |
| 24" | 609.6 | 20 × 35.1 | 1 1/4" | 692.2 | 749.3 | 812.8 |
Kind of value: standard dimension to ASME B16.5 – number of bolt holes Z, bolt hole diameter ØI, stud bolt, raised face ØR, bolt circle ØW, outside diameter ØO. Assignment – pipe outside diameter: it is taken from the pipe standard, not from ASME B16.5.
Class 300 – connection dimensions (1/2"–24")
Show full table · more than 10 rows
| NPS | Pipe OD (mm) 1 | Z × ØI – holes (mm) | Stud – bolts 2 | ØR – Raised Face (mm) | ØW – bolt circle (mm) | ØO – outside (mm) |
|---|---|---|---|---|---|---|
| 1/2" | 21.3 | 4 × 15.7 | 1/2" | 35 | 66.5 | 95.2 |
| 3/4" | 26.7 | 4 × 19 | 5/8" | 42.9 | 82.5 | 117.3 |
| 1" | 33.4 | 4 × 19 | 5/8" | 50.8 | 88.9 | 123.9 |
| 1 1/4" | 42.2 | 4 × 19 | 5/8" | 63.5 | 98.5 | 133.3 |
| 1 1/2" | 48.3 | 4 × 22.3 | 3/4" | 73.1 | 114.3 | 155.4 |
| 2" | 60.3 | 8 × 19 | 5/8" | 91.9 | 127 | 165.1 |
| 2 1/2" | 73.0 | 8 × 22.3 | 3/4" | 104.6 | 149.3 | 190.5 |
| 3" | 88.9 | 8 × 22.3 | 3/4" | 127 | 168.1 | 209.5 |
| 4" | 114.3 | 8 × 22.3 | 3/4" | 157.2 | 200.1 | 254 |
| 5" | 141.3 | 8 × 22.3 | 3/4" | 185.6 | 234.9 | 279.4 |
| 6" | 168.3 | 12 × 22.3 | 3/4" | 215.9 | 269.7 | 317.5 |
| 8" | 219.1 | 12 × 25.4 | 7/8" | 269.7 | 330.2 | 381 |
| 10" | 273.1 | 16 × 28.4 | 1" | 323.8 | 387.3 | 444.5 |
| 12" | 323.9 | 16 × 31.7 | 1 1/8" | 381 | 450.8 | 520.7 |
| 14" | 355.6 | 20 × 31.7 | 1 1/8" | 412.7 | 514.3 | 584.2 |
| 16" | 406.4 | 20 × 35 | 1 1/4" | 469.9 | 571.5 | 647.7 |
| 18" | 457.2 | 24 × 35 | 1 1/4" | 533.4 | 628.6 | 711.2 |
| 20" | 508.0 | 24 × 35 | 1 1/4" | 584.2 | 685.8 | 774.7 |
| 22" 3 | 558.8 | 24 × 41.4 | 1 1/2" | – | 742.9 | 838.2 |
| 24" | 609.6 | 24 × 41.1 | 1 1/2" | 692.1 | 812.8 | 914.4 |
Kind of value: standard dimension to ASME B16.5 – number of bolt holes Z, bolt hole diameter ØI, stud bolt, raised face ØR, bolt circle ØW, outside diameter ØO. Assignment – pipe outside diameter: it is taken from the pipe standard, not from ASME B16.5.
Class 600 – connection dimensions (1/2"–24")
Show full table · more than 10 rows
| NPS | Pipe OD (mm) 1 | Z × ØI – holes (mm) | Stud – bolts 2 | ØR – Raised Face (mm) | ØW – bolt circle (mm) | ØO – outside (mm) |
|---|---|---|---|---|---|---|
| 1/2" | 21.3 | 4 × 15.7 | 1/2" | 35.1 | 66.5 | 95.3 |
| 3/4" | 26.7 | 4 × 19.1 | 5/8" | 42.9 | 82.6 | 117.3 |
| 1" | 33.4 | 4 × 19.1 | 5/8" | 50.8 | 88.9 | 124 |
| 1 1/4" | 42.2 | 4 × 19.1 | 5/8" | 63.5 | 98.6 | 133.4 |
| 1 1/2" | 48.3 | 4 × 22.4 | 3/4" | 73.2 | 114.3 | 155.4 |
| 2" | 60.3 | 8 × 19.1 | 5/8" | 91.9 | 127 | 165.1 |
| 2 1/2" | 73.0 | 8 × 22.4 | 3/4" | 104.6 | 149.4 | 190.5 |
| 3" | 88.9 | 8 × 22.4 | 3/4" | 127 | 168.1 | 209.6 |
| 4" | 114.3 | 8 × 25.4 | 7/8" | 157.2 | 215.9 | 273.1 |
| 5" | 141.3 | 8 × 28.4 | 1" | 185.7 | 266.7 | 330.2 |
| 6" | 168.3 | 12 × 28.4 | 1" | 215.9 | 292.1 | 355.6 |
| 8" | 219.1 | 12 × 31.8 | 1 1/8" | 269.7 | 349.3 | 419.1 |
| 10" | 273.1 | 16 × 35.1 | 1 1/4" | 323.9 | 431.8 | 508 |
| 12" | 323.9 | 20 × 35.1 | 1 1/4" | 381 | 489 | 558.8 |
| 14" | 355.6 | 20 × 38.1 | 1 3/8" | 412.8 | 527 | 603.3 |
| 16" | 406.4 | 20 × 41.1 | 1 1/2" | 469.9 | 603.3 | 685.8 |
| 18" | 457.2 | 20 × 44.5 | 1 5/8" | 533.4 | 654.1 | 743 |
| 20" | 508.0 | 24 × 44.5 | 1 5/8" | 584.2 | 723.9 | 812.8 |
| 22" 3 | 558.8 | 24 × 44.4 | 1 5/8" | – | 778 | 869.9 |
| 24" | 609.6 | 24 × 50.8 | 1 7/8" | 692.2 | 838.2 | 939.8 |
Kind of value: standard dimension to ASME B16.5 – number of bolt holes Z, bolt hole diameter ØI, stud bolt, raised face ØR, bolt circle ØW, outside diameter ØO. Assignment – pipe outside diameter: it is taken from the pipe standard, not from ASME B16.5.
Class 900 – connection dimensions
For Class 900, ASME B16.5 lists a complete range of sizes; our dimension overview does not currently show their dimensions. Tell us the nominal size and design – we will tell you what we know about it.
Class 1500 – connection dimensions
For Class 1500, ASME B16.5 lists a complete range of sizes; our dimension overview does not currently show their dimensions. Tell us the nominal size and design – we will tell you what we know about it.
Class 2500 – connection dimensions
For Class 2500, ASME B16.5 lists a complete range of sizes; our dimension overview does not currently show their dimensions. Tell us the nominal size and design – we will tell you what we know about it.
Further deliverable dimensions (49)
Show full table · more than 40 rows
| NPS | Class |
|---|---|
| 1/2" | Class 1500 |
| 1/2" | Class 2500 |
| 3/4" | Class 1500 |
| 3/4" | Class 2500 |
| 1" | Class 1500 |
| 1" | Class 2500 |
| 1 1/4" | Class 1500 |
| 1 1/4" | Class 2500 |
| 1 1/2" | Class 1500 |
| 1 1/2" | Class 2500 |
| 2" | Class 1500 |
| 2" | Class 2500 |
| 2 1/2" | Class 150 |
| 2 1/2" | Class 1500 |
| 2 1/2" | Class 2500 |
| 3" | Class 1500 |
| 3" | Class 2500 |
| 3" | Class 900 |
| 3 1/2" | Class 150 |
| 3 1/2" | Class 300 |
| 3 1/2" | Class 600 |
| 4" | Class 1500 |
| 4" | Class 2500 |
| 4" | Class 900 |
| 5" | Class 1500 |
| 5" | Class 2500 |
| 5" | Class 900 |
| 6" | Class 1500 |
| 6" | Class 2500 |
| 6" | Class 900 |
| 8" | Class 1500 |
| 8" | Class 2500 |
| 8" | Class 900 |
| 10" | Class 1500 |
| 10" | Class 2500 |
| 10" | Class 900 |
| 12" | Class 1500 |
| 12" | Class 2500 |
| 12" | Class 900 |
| 14" | Class 1500 |
| 14" | Class 900 |
| 16" | Class 1500 |
| 16" | Class 900 |
| 18" | Class 1500 |
| 18" | Class 900 |
| 20" | Class 1500 |
| 20" | Class 900 |
| 24" | Class 1500 |
| 24" | Class 900 |
Order dimensions and values calculated by us; deliverable from stock or procured, availability on request. Limit deviations and figures from the standard: see the main table and the standard itself.
1 Pipe OD = outside diameter of the matching pipe to ASME B36.10M. The flange bore lies somewhat above this (clearance), depending on type, or follows the pipe inside diameter for the welding neck flange – see the note box above.
2 Stud = stud bolt diameter in inches (UNC thread). To ASME B16.5 the hole diameter ØI is always 1/8″ larger than the bolt.
3 22″ (DN 550) is not standardised in ASME B16.5, but is a common manufacturer standard in the trade (cf. MSS SP-44); raised-face diameter per manufacturer data – confirm the bolt-hole pattern and sealing face explicitly when ordering.
Need larger diameters? Above 24″, sizing continues with ASME B16.47 Series A / Series B (NPS 26 – 60). The two series are geometrically different and must not be confused – contact us directly for these sizes.
Find the right flange directly
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Send us your inquiryHow this data is compiled. This page does not reproduce a standard. It shows the dimensions you need for an enquiry, an order and installation – for sizes we supply, checked against documents from manufacturing works and suppliers and against our own range. Each value states what kind of value it is: specified by the standard, calculated by us or customary in the trade. The currently valid standard is binding. It is available from DIN Media or from your national standards body. How we select our sources and keep them up to date: About this knowledge.
Technical basis: ASME B16.5. All information without guarantee – the current standard texts and the manufacturers’ technical data sheets always prevail. Values selected according to our delivery and stock programme; compiled from our own ERP data and long-standing trading practice, cross-checked against publicly available manufacturer information. These tables do not replace the standard text – the current edition of the standard always governs.