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.
Choose the flange type and pressure class
Which flange type to ASME B16.5 comes in which pressure class? Each cell gives the nominal pipe sizes with a dimensional drawing and leads straight to the type page with the class preselected.
| Flange type | Class 150 | Class 300 | Class 400 | Class 600 | Class 900 | Class 1500 | Class 2500 |
|---|---|---|---|---|---|---|---|
| WN · Weld neck flange | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–12 |
| SO · Slip-on flange | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–2 1/2 | – |
| TH · Threaded flange | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–2 1/2 | NPS 1/2–2 1/2 |
| SW · Socket weld flange | NPS 1/2–3 | NPS 1/2–3 | NPS 1/2–3 | NPS 1/2–3 | NPS 1/2–2 1/2 | NPS 1/2–2 1/2 | – |
| LJ · Lap joint flange with stub end | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–12 |
| BL · Blind flange | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–24 | NPS 1/2–12 |
- type and class with sizes from our range
- available to order
- – not standardised or not documented in our sources · “except”: this size is standardised, its dimensions are not fully documented in our sources
The overview shows where dimensional drawings exist – the dimensions themselves are on the type pages and in the tables below.
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 20 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 |
| 2 1/2" | 73.0 | 4 × 19.1 | 5/8" | 104.6 | 139.7 | 177.8 |
| 3" | 88.9 | 4 × 19.1 | 5/8" | 127 | 152.4 | 190.5 |
| 3 1/2" | 101.6 | 8 × 19.1 | 5/8" | 139.7 | 177.8 | 215.9 |
| 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 20 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 |
| 3 1/2" | 101.6 | 8 × 22.3 | 3/4" | 139.7 | 184.1 | 228.6 |
| 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 20 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 |
| 3 1/2" | 101.6 | 8 × 25.4 | 7/8" | 139.7 | 184.2 | 228.6 |
| 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 (10"–10")
| NPS | Pipe OD (mm) 1 | Z × ØI – holes (mm) | Stud – bolts 2 | ØR – Raised Face (mm) | ØW – bolt circle (mm) | ØO – outside (mm) |
|---|---|---|---|---|---|---|
| 10" | 273.1 | 16 × 38.1 | 1 3/8" | 323.9 | 469.9 | 546.1 |
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 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 (1 1/2"–1 1/2")
| NPS | Pipe OD (mm) 1 | Z × ØI – holes (mm) | Stud – bolts 2 | ØR – Raised Face (mm) | ØW – bolt circle (mm) | ØO – outside (mm) |
|---|---|---|---|---|---|---|
| 1 1/2" | 48.3 | 4 × 31.8 | 1 1/8" | 73.2 | 146 | 203.2 |
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.
Further deliverable dimensions (50)
Show full table · more than 40 rows
| NPS | Class |
|---|---|
| 1/2" | Class 1500 |
| 1/2" | Class 2500 |
| 1/2" | Class 900 |
| 3/4" | Class 1500 |
| 3/4" | Class 2500 |
| 3/4" | Class 900 |
| 1" | Class 1500 |
| 1" | Class 2500 |
| 1" | Class 900 |
| 1 1/4" | Class 1500 |
| 1 1/4" | Class 2500 |
| 1 1/4" | Class 900 |
| 1 1/2" | Class 1500 |
| 1 1/2" | Class 900 |
| 2" | Class 1500 |
| 2" | Class 2500 |
| 2" | Class 900 |
| 2 1/2" | Class 1500 |
| 2 1/2" | Class 2500 |
| 2 1/2" | Class 900 |
| 3" | Class 1500 |
| 3" | Class 2500 |
| 3" | Class 900 |
| 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 |
| 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 to order, 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.
Frequently asked questions
Where do I find ASME B16.5 flange dimensions in millimetres?
The dimension table on this page gives the dimensions per NPS and class to ASME B16.5 in millimetres with inches in brackets.
What does ASME cover, what does ASTM? Dimensions to ASME B16.5 say nothing about the material – that comes from an ASTM standard such as A105 or A182. The profiles show for each standard what it covers, which grades exist and which of them we supply. To the ASME/ASTM profiles
Weld neck flange ASME B16.5 in detail The weld neck flange (WN) has its own page: choose class and NPS – and you get a dimensional drawing with tolerances, measuring notes and the dimension tables for each class. To the weld neck flange ASME B16.5
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How 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 manufacturers’ and suppliers’ documentation and against our own product data. What you see here is what the market supplies, checked against the standard – or calculated by us. 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.