Flanges · ASME B16.5
Weld neck flange: dimensions and dimensional drawing to ASME B16.5
All dimensions of the weld neck flange to ASME B16.5 in one table, the dimensional drawing of your size above it – available from stock or to order. Weld neck flanges to ASME B16.5 (WN) from NPS 1/2 to 24 in pressure classes 150 to 2500. Choose the class and nominal pipe size: drawing and dimension table show outside diameter O, flange thickness tf, bolt circle W, bolt holes, hub X, welding end Ah, length through hub Y and bore B – in millimetres, with the inch value in brackets, and with the tolerances.
- Standard
- ASME B16.5-2025 – dimensions from manufacturers’ and suppliers’ documentation, checked against the standard
- Sizes
- NPS 1/2 to 24 · Class 150, 300, 400, 600, 900, 1500, 2500
- Facing
- raised face RF (standard) – RTJ with ring groove on request
- Dimension letters
- to ASME B16.5: O, tf, R, W, Z × ØI, X, Ah, Y, B
Dimensional drawing for your size
The dimensional drawing – also called dimension sheet, outline drawing or dimension sketch – shows every dimension, the bolt pattern and the tolerances for your size.
How it works: Choose Class 150 in the field “Pressure class” and NPS 4 in the field “Nominal pipe size (NPS)”. The dimensional drawing immediately shows every dimension of the weld neck flange with tolerances, the table below all sizes. “Print this size as PDF” takes the drawing with you.
Example NPS 4 Class 150: outside diameter O 228.6 mm (9 in), bolt circle diameter W 190.5 mm, bolt holes Z × I 8 × ⌀19.1 mm, stud bolt 5/8", flange thickness tf 22.4 mm (0.9 in), raised face diameter R 157.2 mm, weight 7.1 kg.
Direct link to this size: https://www.zickwolff.de/wissen/en/flanges/weld-neck-flange-asme-b16-5/?class=150&nps=4
Choose the pressure class and nominal pipe size – the drawing and dimension table then show exactly this version, with the values written directly in the drawing instead of just the dimension letters. The tables for the nominal sizes covered here are further down the page.
Weld neck flange · ASME B16.5 · NPS 4 · Class 150
Technical basis: ASME B16.5:2025. Zickwolff has prepared this presentation for practical use, with our own structure, our own designations and a statement of what kind of value each figure is. The original standard governs normative requirements.
| Property | Value | Type of information |
|---|---|---|
| basic data | ||
| Nominal pipe size | NPS 4 | market dimension |
| Pressure class | Class 150 | market dimension |
| weight | 7.1 kg | calculated |
| Source of the values | two market documents in agreement | market dimension |
| connecting dimensions The dimensions that decide the fit with the mating flange. | ||
| outside diameter O | 228.6 mm (9 in) | market dimension |
| bolt circle diameter W | 190.5 mm | market dimension |
| bolt holes Z × I | 8 × ⌀19.1 mm | market dimension |
| stud bolt | 5/8" | market dimension |
| flange thickness tf | 22.4 mm (0.9 in) | market dimension |
| sealing face | ||
| raised face diameter R | 157.2 mm | market dimension |
| raised face height (RF) | 1.5 mm | market dimension |
| hub and welding end | ||
| hub diameter X | 134.9 mm (5.3 in) | market dimension |
| diameter at welding end Ah | 114.3 mm (4.5 in) – pipe outside diameter to ASME B36.10M | market dimension |
| length through hub Y | 74.7 mm (2.9 in) | market dimension |
| bore B | 102.4 mm (4 in) – bore for STD (catalogue) | market dimension |
| Bore B per schedule (pipe inside diameter to ASME B36.10M, calculated) | SCH 5: 110.1 mm · SCH 10: 108.2 mm · SCH 30: 104.7 mm · STD = SCH 40: 102.3 mm · XS = SCH 80: 97.2 mm · SCH 120: 92 mm · SCH 160: 87.3 mm · XXS: 80.1 mm | calculated |
| wall thickness at the welding end (calculated) | 5.9 mm | calculated |
Without an entry in the “Type of information” column: standard dimension. A dimension that ASME B16.5 specifies for this size.
Where exactly it is measured
- outside diameter O
- largest diameter of the flange plate, measured across the edge
- bolt circle diameter W
- diameter of the circle through the hole centres – with an even number of holes, from hole centre to opposite hole centre
- bolt holes Z × I
- count the holes, then measure one hole – the hole is 1/8 in (3.2 mm) larger than the bolt
- stud bolt
- bolt diameter in inches (UNC thread) – length by facing RF or RTJ from the bolting table
- flange thickness tf
- minimum thickness of the flange plate WITHOUT the raised face – measure from the back face to the foot of the raised face – the raised face (1.5 mm for Class 150/300, 6.4 mm from Class 400) is added. Older tables (dimension C, before 2003) included the raised face for Class 150/300
- raised face diameter R
- outside diameter of the raised face, measured across its edge – for RTJ flanges the ring groove to Table 5 applies instead
- hub diameter X
- measure at the transition to the flange plate, where the hub is thickest – the hub may be straight or tapered (Figure 4 of the standard)
- diameter at welding end Ah
- outside diameter of the hub at the welding bevel = pipe outside diameter to B36.10M – take it at the end plane on the extended outside surface
- length through hub Y
- overall length from the flange face (without raised face) to the welding bevel
- bore B
- inside diameter at the welding end, matching the pipe wall: standard wall (Class 150/300) or extra strong (Class 600) per catalogue – for other schedules a purchase specification
- weight
- calculated by Zickwolff from the nominal dimensions at 7.85 kg/dm³ – guide value, not a standard value
- raised face height (RF)
- Stands proud of the flange face and is not included in tf – 1.5 mm up to Class 300, 6.4 mm from Class 400.
- wall thickness at the welding end (calculated)
- Calculated from Ah and B: (Ah − B) / 2. Not a catalogue value.
notes on the design
These values apply equally to every size of this type and are therefore not given in the dimension table.
- Weld preparation statement of the standard
- bevel 37.5° ±2.5, root face 1.6 ±0.8 mm (ASME B16.25)
Tolerances (limit deviations): what range the standard permits
For each dimension the permissible range is given – to ASME B16.5, for O and X to the manufacturers’ values, because the standard does not limit these two dimensions. Minimum and maximum are shown instead of the deviation that would first have to be worked out. In the drawing this is shortened to tolerance – the word everyone uses in practice. In technical terms the two values given are the limit dimensions of the dimension, their distance is the tolerance and the deviations from the nominal size are the limit deviations. The basis is section 7 (tolerances). Where the standard specifies nothing, that is stated.
Further properties with limit deviations
These properties have no nominal dimension in the dimension table, but the standard limits them. For incoming inspection they are often the decisive ones – they are what makes a bolted joint fail on site.
| spacing of adjacent bolt holes | limit deviation ±0.8 mm |
|---|---|
| concentricity of bolt circle and facing | at most 1.5 mm |
| perpendicularity of the face to the bore B | at most 1° |
Measuring on the part: the dimensions in the picture
Every dimension has its reason – whoever knows why they measure, measures better.
Where the standard gives no limit deviation of its own
- outside diameter O – The standard specifies no tolerance for the outside diameter – it affects neither fit-up nor sealing (B16.5 Appendix F-2.3). Manufacturer catalogues supply ±1.6 mm up to 24 in.
- hub diameter X – The standard specifies no tolerance for the hub diameter at the base. Manufacturer catalogues supply ±1.6 mm up to 24 in.
Sources of the limit deviations (11 entries)
- spacing of adjacent bolt holes – bolt hole to bolt hole
- concentricity of bolt circle and facing – concentricity from NPS 3
- perpendicularity of the face to the bore B – perpendicularity of the face to the bore B up to NPS 5
- outside diameter – B16.5 Appendix F-2.3: outside diameter untoleranced – catalogue value up to 24 in in the note
- bolt circle diameter – bolt circle
- raised face diameter – raised face 1/16 in (Class 150/300)
- flange thickness – flange thickness up to NPS 18
- hub diameter – hub diameter at base untoleranced in B16.5 – catalogue value up to 24 in in the note
- diameter at welding end – diameter at welding end up to NPS 5
- length through hub – length through hub up to NPS 4
- bore – bore at welding end up to NPS 10
This information does not replace the standard itself. Only the limit deviations for the size selected here are reproduced. In full – for the sizes shown, NPS 1/2 to 24, Class 150 to 2500 – they are given in ASME B16.5:2025, section 7 (tolerances). The standard is available from ASME. We have reproduced the values on this page from the manufacturers’ tolerance tables. For the outside diameter O and the hub diameter X the standard sets no tolerance – the manufacturers’ values apply there. The perpendicularity of the face to the bore B is not in the tables – it is given according to the standard.
Why limit deviations exist at all and how to read them is explained on a page of its own: Tolerances and limit deviations.
Dimensions are nominal dimensions to ASME B16.5 and do not replace the data sheet of the actual item. No statement about pressure or temperature suitability and no statement about the material. NPS is a reference number in inches, not a dimension – the pipe outside diameter Ah differs from it up to NPS 12. Direct link to this size
Where it is measured – at the welding end
Measured at the welding end of the hub, at the end plane – hub diameter A on the extended outside surface, bore B at the root face, as B16.25 enters both. The wall follows from A and B – the root face is not the wall.
ASME B16.5 dimensions the welding end of a welding-neck flange with the hub diameter A, which corresponds to the pipe outside diameter, and the bore B, which is ordered to the pipe wall (schedule). Both apply at the end plane of the hub end, as B16.25 (figure 3.1-1) enters them – A across the extended cylindrical outside surface, B as the inside diameter at the root face – the bevel only appears to cut the wall. The bevel is 37,5° ± 2,5° with a root face of 1,6 ± 0,8 mm to B16.25. The tolerances come from annex F of B16.5 – the bore B is an ordering detail and not a standard value above NPS 12.
Typical measuring error: Comparing the bore B with a table value although it was ordered to a different schedule – B follows the order, not the table.
Rule of thumb: The bore B is an ordering detail, not a standard value.
The dimension letters of ASME B16.5
Dimension letters to ASME B16.5. Manufacturers’ catalogues partly use other abbreviations, for example T or C for tf and BC for W.
- O – outside diameter of the flange plate
- tf – flange thickness without raised face
- R – diameter of the raised face
- W – bolt circle diameter
- Z × ØI – number and diameter of bolt holes
- X – hub diameter at the plate
- Ah – diameter at the welding end – the pipe outside diameter
- Y – length through hub, from the flange face without raised face
- B – bore (inside diameter at the welding end) – purchase specification by schedule
Class instead of PN
Class instead of PN: the pressure class does not say what pressure the flange holds – that is in the pressure–temperature table of the material group. A Class 150 flange in A105 carries 19.6 bar at 38 °C, considerably less at 200 °C – Class 150 is not 150 psi. The table counts for design, the class for ordering.
More on this: rule of thumb Class 150.
How to measure correctly
- Flange thickness tf: measure from the back of the plate to the foot of the raised face, not across the face. Since the 2003 edition the standard gives the thickness without the raised face for all classes – the raised face (1.5 mm for Class 150 and 300, 6.4 mm from Class 400) is added. Anyone comparing with an older table (dimension C) finds values 1/16 in larger for Class 150/300 – it is the same flange.
- Hub: the hub diameter X is measured at the transition to the plate, the diameter A at the welding bevel – A is the pipe outside diameter. The hub may be tapered or straight – straight hub flanges exist as a series of their own (Figure 4 of the standard) with the same connecting dimensions.
- Bore B: the bore is a purchase specification – it follows the wall thickness (schedule) of the pipe, not the class. The catalogues give standard wall (Class 150/300) or extra strong (Class 600) as default – anyone welding a different schedule orders the bore with it (“SCH 80 bore”). The hub wall at the welding end must be at least 87.5 % of the nominal pipe wall.
- Facing: the default is the raised face (RF) with stock finish – ring joint (RTJ) has a ring groove instead of the raised face, needs longer stud bolts and a different overall thickness. The connecting dimensions O, W and holes stay the same.
- Facing roughness: the usual supply is the stock finish with a spiral groove, roughness about 3.2 to 6.3 µm Ra (125 to 250 µin) – intended for soft and spiral-wound gaskets. Smooth finishes are ordered, not assumed. Permissible imperfections are regulated by the standard per raised face diameter.
Dimensions per pressure class
Values in mm from manufacturers’ and suppliers’ documentation, checked against ASME B16.5-2025. A dash means: not documented in our sources. tf without raised face, Y from the flange face without raised face, B for standard wall (Class 150/300) or extra strong (Class 600).
What the dimension letters mean
- NPS
- nominal pipe size NPS – nominal pipe size: determines the bore and the hub diameter at the welding end – not the outside diameter of the flange plate
- O
- outside diameter O – largest diameter of the flange plate, measured across the edge
- tf
- flange thickness tf – minimum thickness of the flange plate WITHOUT the raised face – measure from the back face to the foot of the raised face – the raised face (1.5 mm for Class 150/300, 6.4 mm from Class 400) is added. Older tables (dimension C, before 2003) included the raised face for Class 150/300
- R
- raised face diameter R – outside diameter of the raised face, measured across its edge – for RTJ flanges the ring groove to Table 5 applies instead
- W
- bolt circle diameter W – diameter of the circle through the hole centres – with an even number of holes, from hole centre to opposite hole centre
- Z × ØI
- bolt holes Z × ØI – count the holes, then measure one hole – the hole is 1/8 in (3.2 mm) larger than the bolt
- Stud
- stud bolt – bolt diameter in inches (UNC thread) – length by facing RF or RTJ from the bolting table
- X
- hub diameter X – measure at the transition to the flange plate, where the hub is thickest – the hub may be straight or tapered (Figure 4 of the standard)
- Ah
- diameter at welding end Ah – outside diameter of the hub at the welding bevel = pipe outside diameter to B36.10M – take it at the end plane on the extended outside surface
- Y
- length through hub Y – overall length from the flange face (without raised face) to the welding bevel
- B
- bore B – inside diameter at the welding end, matching the pipe wall: standard wall (Class 150/300) or extra strong (Class 600) per catalogue – for other schedules a purchase specification
- G (kg)
- weight G – catalogue value approx., standard bore – trade figure, not a standard value
The weld neck flange is also available with a long hub or as an orifice flange to ASME B16.36 – on request.
Show full table · more than 20 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 88.9 | 9.7 | 35.1 | 60.5 | 4 × 15.7 | 1/2" | 30.2 | 21.3 | 46.0 | 15.7 | 0.5 |
| NPS 3/4 | 98.6 | 11.2 | 42.9 | 69.9 | 4 × 15.7 | 1/2" | 38.1 | 26.7 | 50.8 | 20.8 | 0.74 |
| NPS 1 | 108 | 12.7 | 50.8 | 79.2 | 4 × 15.7 | 1/2" | 49.3 | 33.4 | 53.8 | 26.7 | 1.1 |
| NPS 1 1/4 | 117.3 | 14.2 | 63.5 | 88.9 | 4 × 15.7 | 1/2" | 58.7 | 42.2 | 55.6 | 35.1 | 1.4 |
| NPS 1 1/2 | 127 | 15.7 | 73.2 | 98.6 | 4 × 15.7 | 1/2" | 65.0 | 48.3 | 60.5 | 40.9 | 1.8 |
| NPS 2 | 152.4 | 17.5 | 91.9 | 120.7 | 4 × 19.1 | 5/8" | 77.7 | 60.3 | 62.0 | 52.6 | 2.7 |
| NPS 2 1/2 | 177.8 | 20.6 | 104.6 | 139.7 | 4 × 19.1 | 5/8" | 90.4 | 73.0 | 68.3 | 62.7 | 4.2 |
| NPS 3 | 190.5 | 22.4 | 127 | 152.4 | 4 × 19.1 | 5/8" | 108.0 | 88.9 | 68.3 | 78.0 | 5.1 |
| NPS 3 1/2 | 215.9 | 22.4 | 139.7 | 177.8 | 8 × 19.1 | 5/8" | 122.2 | 101.6 | 69.9 | 90.2 | 6.3 |
| NPS 4 | 228.6 | 22.4 | 157.2 | 190.5 | 8 × 19.1 | 5/8" | 134.9 | 114.3 | 74.7 | 102.4 | 7.1 |
| NPS 5 | 254 | 22.4 | 185.7 | 215.9 | 8 × 22.4 | 3/4" | 163.6 | 141.3 | 87.4 | 128.3 | 9 |
| NPS 6 | 279.4 | 23.9 | 215.9 | 241.3 | 8 × 22.4 | 3/4" | 192.0 | 168.3 | 87.4 | 154.2 | 11 |
| NPS 8 | 342.9 | 26.9 | 269.7 | 298.5 | 8 × 22.4 | 3/4" | 246.1 | 219.1 | 100.1 | 202.7 | 18.2 |
| NPS 10 | 406.4 | 28.4 | 323.9 | 362 | 12 × 25.4 | 7/8" | 304.8 | 273.1 | 100.1 | 254.5 | 24.9 |
| NPS 12 | 482.6 | 30.2 | 381 | 431.8 | 12 × 25.4 | 7/8" | 365.3 | 323.9 | 112.8 | 304.8 | 38.3 |
| NPS 14 | 533.4 | 33.3 | 412.8 | 476.3 | 12 × 28.4 | 1" | 400.1 | 355.6 | 125.5 | 336.6 | 50.5 |
| NPS 16 | 596.9 | 35.1 | 469.9 | 539.8 | 16 × 28.4 | 1" | 457.2 | 406.4 | 125.5 | 387.4 | 62.9 |
| NPS 18 | 635 | 38.1 | 533.4 | 577.9 | 16 × 31.8 | 1 1/8" | 505.0 | 457.2 | 138.2 | 438.2 | 71.1 |
| NPS 20 | 698.5 | 41.1 | 584.2 | 635 | 20 × 31.8 | 1 1/8" | 558.8 | 508.0 | 142.7 | 489.0 | 87.4 |
| NPS 22 | 749.3 | 44.5 | 641.4 | 692.1 | 20 × 35.1 | 1 1/4" | 610.0 | 558.8 | 147.8 | 539.8 | 100.5 |
| NPS 24 | 812.8 | 46.0 | 692.2 | 749.3 | 20 × 35.1 | 1 1/4" | 663.4 | 609.6 | 150.9 | 590.6 | 119.2 |
Show full table · more than 20 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.2 | 12.7 | 35 | 66.5 | 4 × 15.7 | 1/2" | 38.1 | 21.3 | 50.8 | 15.7 | 0.78 |
| NPS 3/4 | 117.3 | 14.2 | 42.9 | 82.5 | 4 × 19 | 5/8" | 47.8 | 26.7 | 55.6 | 20.8 | 1.3 |
| NPS 1 | 123.9 | 15.7 | 50.8 | 88.9 | 4 × 19 | 5/8" | 53.8 | 33.4 | 60.5 | 26.7 | 1.6 |
| NPS 1 1/4 | 133.3 | 17.5 | 63.5 | 98.5 | 4 × 19 | 5/8" | 63.5 | 42.2 | 63.5 | 35.1 | 2.1 |
| NPS 1 1/2 | 155.4 | 19.1 | 73.1 | 114.3 | 4 × 22.3 | 3/4" | 69.9 | 48.3 | 66.8 | 40.9 | 3 |
| NPS 2 | 165.1 | 20.6 | 91.9 | 127 | 8 × 19 | 5/8" | 84.1 | 60.3 | 68.3 | 52.6 | 3.5 |
| NPS 2 1/2 | 190.5 | 23.9 | 104.6 | 149.3 | 8 × 22.3 | 3/4" | 100.1 | 73.0 | 74.7 | 62.7 | 5.4 |
| NPS 3 | 209.5 | 26.9 | 127 | 168.1 | 8 × 22.3 | 3/4" | 117.3 | 88.9 | 77.7 | 78.0 | 7.1 |
| NPS 3 1/2 | 228.6 | 28.4 | 139.7 | 184.1 | 8 × 22.3 | 3/4" | 133.4 | 101.6 | 79.5 | 90.2 | 8.9 |
| NPS 4 | 254 | 30.2 | 157.2 | 200.1 | 8 × 22.3 | 3/4" | 146.1 | 114.3 | 84.3 | 102.4 | 11.6 |
| NPS 5 | 279.4 | 33.3 | 185.6 | 234.9 | 8 × 22.3 | 3/4" | 177.8 | 141.3 | 97.0 | 128.3 | 15.6 |
| NPS 6 | 317.5 | 35.1 | 215.9 | 269.7 | 12 × 22.3 | 3/4" | 206.2 | 168.3 | 97.0 | 154.2 | 19.9 |
| NPS 8 | 381 | 39.6 | 269.7 | 330.2 | 12 × 25.4 | 7/8" | 260.4 | 219.1 | 109.7 | 202.7 | 31 |
| NPS 10 | 444.5 | 46.0 | 323.8 | 387.3 | 16 × 28.4 | 1" | 320.5 | 273.1 | 115.8 | 254.5 | 44.5 |
| NPS 12 | 520.7 | 49.3 | 381 | 450.8 | 16 × 31.7 | 1 1/8" | 374.7 | 323.9 | 128.5 | 304.8 | 64.1 |
| NPS 14 | 584.2 | 52.3 | 412.7 | 514.3 | 20 × 31.7 | 1 1/8" | 425.5 | 355.6 | 141.2 | 336.6 | 89.3 |
| NPS 16 | 647.7 | 55.6 | 469.9 | 571.5 | 20 × 35 | 1 1/4" | 482.6 | 406.4 | 144.5 | 387.4 | 110.9 |
| NPS 18 | 711.2 | 58.7 | 533.4 | 628.6 | 24 × 35 | 1 1/4" | 533.4 | 457.2 | 157.2 | 438.2 | 136.4 |
| NPS 20 | 774.7 | 62.0 | 584.2 | 685.8 | 24 × 35 | 1 1/4" | 587.2 | 508.0 | 160.5 | 489.0 | 164.9 |
| NPS 22 | 838.2 | 65.3 | 641.4 | 742.9 | 24 × 41.4 | 1 1/2" | 641.4 | 558.8 | 163.3 | 539.8 | 192 |
| NPS 24 | 914.4 | 68.3 | 692.1 | 812.8 | 24 × 41.1 | 1 1/2" | 701.5 | 609.6 | 166.6 | 590.6 | 238.8 |
Show full table · more than 20 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.3 | 14.2 | 35.1 | 66.5 | 4 × 16.0 | 0.505" | 38.1 | 21.3 | 52.3 | – | 0.88 |
| NPS 3/4 | 117.3 | 15.7 | 42.9 | 82.6 | 4 × 19.1 | 0.625" | 47.8 | 26.7 | 57.2 | – | 1.5 |
| NPS 1 | 124.0 | 17.5 | 50.8 | 88.9 | 4 × 19.1 | 0.625" | 53.8 | 33.5 | 62.0 | – | 1.8 |
| NPS 1 1/4 | 133.4 | 20.6 | 63.5 | 98.6 | 4 × 19.1 | 0.625" | 63.5 | 42.2 | 66.5 | – | 2.5 |
| NPS 1 1/2 | 155.4 | 22.4 | 73.2 | 114.3 | 4 × 22.4 | 0.755" | 69.9 | 48.3 | 69.9 | – | 3.5 |
| NPS 2 | 165.1 | 25.4 | 91.9 | 127.0 | 8 × 19.1 | 0.625" | 84.1 | 60.5 | 73.2 | – | 4.3 |
| NPS 2 1/2 | 190.5 | 28.4 | 104.6 | 149.4 | 8 × 22.4 | 0.755" | 100.1 | 73.2 | 79.2 | – | 6.4 |
| NPS 3 | 209.6 | 31.8 | 127.0 | 168.1 | 8 × 22.4 | 0.755" | 117.3 | 88.9 | 82.6 | – | 8.5 |
| NPS 3 1/2 | 228.6 | 35.1 | 139.7 | 184.2 | 8 × 25.4 | 0.875" | 133.4 | 101.6 | 85.9 | – | 10.7 |
| NPS 4 | 254.0 | 35.1 | 157.2 | 200.2 | 8 × 25.4 | 0.875" | 146.1 | 114.3 | 88.9 | – | 13.3 |
| NPS 5 | 279.4 | 38.1 | 185.7 | 235.0 | 8 × 25.4 | 0.875" | 177.8 | 141.2 | 101.6 | – | 17.6 |
| NPS 6 | 317.5 | 41.1 | 215.9 | 269.7 | 12 × 25.4 | 0.875" | 206.2 | 168.4 | 103.1 | – | 22.8 |
| NPS 8 | 381.0 | 47.8 | 269.7 | 330.2 | 12 × 28.4 | 0.995" | 260.4 | 219.2 | 117.3 | – | 36.1 |
| NPS 10 | 444.5 | 53.8 | 323.9 | 387.4 | 16 × 31.8 | 1.125" | 320.5 | 273.1 | 124.0 | – | 50.5 |
| NPS 12 | 520.7 | 57.2 | 381.0 | 450.9 | 16 × 35.1 | 1.255" | 374.7 | 323.9 | 136.7 | – | 72.4 |
| NPS 14 | 584.2 | 60.5 | 412.8 | 514.4 | 20 × 35.1 | 1.255" | 425.5 | 355.6 | 149.4 | – | 99.9 |
| NPS 16 | 647.7 | 63.5 | 469.9 | 571.5 | 20 × 38.1 | 1.375" | 482.6 | 406.4 | 152.4 | – | 123.3 |
| NPS 18 | 711.2 | 66.5 | 533.4 | 628.7 | 24 × 38.1 | 1.375" | 533.4 | 457.2 | 165.1 | – | 151 |
| NPS 20 | 774.7 | 69.9 | 584.2 | 685.8 | 24 × 41.1 | 1.495" | 587.2 | 508.0 | 168.1 | – | 179.3 |
| NPS 22 | 838.2 | 73.2 | 641.4 | 743.0 | 24 × 44.5 | 1.625" | 641.4 | 558.8 | 171.5 | – | 210.7 |
| NPS 24 | 914.4 | 76.2 | 692.2 | 812.8 | 24 × 47.8 | 1.755" | 701.5 | 609.6 | 174.8 | – | 257.5 |
Show full table · more than 20 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.3 | 14.2 | 35.1 | 66.5 | 4 × 15.7 | 1/2" | 38.1 | 21.3 | 52.3 | 14.0 | 0.9 |
| NPS 3/4 | 117.3 | 15.7 | 42.9 | 82.6 | 4 × 19.1 | 5/8" | 47.8 | 26.7 | 57.2 | 18.8 | 1.5 |
| NPS 1 | 124 | 17.5 | 50.8 | 88.9 | 4 × 19.1 | 5/8" | 53.8 | 33.4 | 62.0 | 24.4 | 1.9 |
| NPS 1 1/4 | 133.4 | 20.6 | 63.5 | 98.6 | 4 × 19.1 | 5/8" | 63.5 | 42.2 | 66.5 | 32.5 | 2.6 |
| NPS 1 1/2 | 155.4 | 22.4 | 73.2 | 114.3 | 4 × 22.4 | 3/4" | 69.9 | 48.3 | 69.9 | 38.1 | 3.6 |
| NPS 2 | 165.1 | 25.4 | 91.9 | 127 | 8 × 19.1 | 5/8" | 84.1 | 60.3 | 73.2 | 49.3 | 4.5 |
| NPS 2 1/2 | 190.5 | 28.4 | 104.6 | 149.4 | 8 × 22.4 | 3/4" | 100.1 | 73.0 | 79.2 | 58.9 | 6.6 |
| NPS 3 | 209.6 | 31.8 | 127 | 168.1 | 8 × 22.4 | 3/4" | 117.3 | 88.9 | 82.6 | 73.7 | 8.8 |
| NPS 3 1/2 | 228.6 | 35.1 | 139.7 | 184.2 | 8 × 25.4 | 7/8" | 133.4 | 101.6 | 85.9 | 85.3 | 11.2 |
| NPS 4 | 273.1 | 38.1 | 157.2 | 215.9 | 8 × 25.4 | 7/8" | 152.4 | 114.3 | 101.6 | 97.3 | 18 |
| NPS 5 | 330.2 | 44.5 | 185.7 | 266.7 | 8 × 28.4 | 1" | 189.0 | 141.3 | 114.3 | 122.2 | 30.2 |
| NPS 6 | 355.6 | 47.8 | 215.9 | 292.1 | 12 × 28.4 | 1" | 222.3 | 168.3 | 117.3 | 146.3 | 36.4 |
| NPS 8 | 419.1 | 55.6 | 269.7 | 349.3 | 12 × 31.8 | 1 1/8" | 273.1 | 219.1 | 133.4 | 193.8 | 55.7 |
| NPS 10 | 508 | 63.5 | 323.9 | 431.8 | 16 × 35.1 | 1 1/4" | 342.9 | 273.1 | 152.4 | 247.7 | 89.6 |
| NPS 12 | 558.8 | 66.5 | 381 | 489 | 20 × 35.1 | 1 1/4" | 400.1 | 323.9 | 155.4 | 298.5 | 106.9 |
| NPS 14 | 603.3 | 69.9 | 412.8 | 527 | 20 × 38.1 | 1 3/8" | 431.8 | 355.6 | 165.1 | 330.2 | 127 |
| NPS 16 | 685.8 | 76.2 | 469.9 | 603.3 | 20 × 41.1 | 1 1/2" | 495.3 | 406.4 | 177.8 | 381.0 | 176.7 |
| NPS 18 | 743 | 82.6 | 533.4 | 654.1 | 20 × 44.5 | 1 5/8" | 546.1 | 457.2 | 184.2 | 431.8 | 211.1 |
| NPS 20 | 812.8 | 88.9 | 584.2 | 723.9 | 24 × 44.5 | 1 5/8" | 609.6 | 508.0 | 190.5 | 482.6 | 262.9 |
| NPS 22 | 869.9 | 95.3 | 641.4 | 778 | 24 × 44.4 | 1 5/8" | 663.0 | 558.8 | 196.9 | – | 310.5 |
| NPS 24 | 939.8 | 101.6 | 692.2 | 838.2 | 24 × 50.8 | 1 7/8" | 717.6 | 609.6 | 203.2 | 584.2 | 368.8 |
Show full table · more than 10 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 120.6 | 22.4 | 35.1 | 82.5 | 4 × 22.4 | 3/4" | 38.1 | 21.3 | 60.5 | – | 1.9 |
| NPS 3/4 | 130 | 25.4 | 42.9 | 88.9 | 4 × 22.4 | 3/4" | 44.5 | 26.7 | 69.9 | – | 2.6 |
| NPS 1 | 149.4 | 28.4 | 50.8 | 101.6 | 4 × 25.4 | 7/8" | 52.3 | 33.4 | 73.2 | – | 3.7 |
| NPS 1 1/4 | 158.8 | 28.4 | 63.5 | 111.3 | 4 × 25.4 | 7/8" | 63.5 | 42.2 | 73.2 | – | 4.3 |
| NPS 1 1/2 | 177.8 | 31.8 | 73.2 | 124 | 4 × 28.4 | 1" | 69.9 | 48.3 | 82.6 | – | 6 |
| NPS 2 | 215.9 | 38.1 | 91.9 | 165.1 | 8 × 25.4 | 7/8" | 104.6 | 60.3 | 101.6 | – | 11 |
| NPS 2 1/2 | 244.3 | 41.1 | 104.6 | 190.5 | 8 × 28.4 | 1" | 124.0 | 73.0 | 104.6 | – | 15.1 |
| NPS 3 | 241.3 | 38.1 | 127 | 190.5 | 8 × 25.4 | 7/8" | 127.0 | 88.9 | 101.6 | – | 13.7 |
| NPS 4 | 292.1 | 44.5 | 157.2 | 234.9 | 8 × 31.8 | 1 1/8" | 158.8 | 114.3 | 114.3 | – | 22.5 |
| NPS 5 | 349.2 | 50.8 | 185.7 | 279.4 | 8 × 35.1 | 1 1/4" | 190.5 | 141.3 | 127.0 | – | 36 |
| NPS 6 | 381 | 55.6 | 215.9 | 317.5 | 12 × 31.8 | 1 1/8" | 235.0 | 168.3 | 139.7 | – | 47.3 |
| NPS 8 | 469.9 | 63.5 | 269.7 | 393.7 | 12 × 38.1 | 1 3/8" | 298.5 | 219.1 | 162.1 | – | 80.8 |
| NPS 10 | 546.1 | 69.9 | 323.9 | 469.9 | 16 × 38.1 | 1 3/8" | 368.3 | 273.1 | 184.2 | – | 119.6 |
| NPS 12 | 609.6 | 79.2 | 381 | 533.4 | 20 × 38.1 | 1 3/8" | 419.1 | 323.9 | 200.2 | – | 159.4 |
| NPS 14 | 641.3 | 85.9 | 412.8 | 558.8 | 20 × 41.4 | 1 1/2" | 450.9 | 355.6 | 212.9 | – | 184.1 |
| NPS 16 | 704.8 | 88.9 | 469.9 | 615.9 | 20 × 44.4 | 1 5/8" | 508.0 | 406.4 | 215.9 | – | 224.8 |
| NPS 18 | 787.4 | 101.6 | 533.4 | 685.8 | 20 × 50.8 | 1 7/8" | 565.2 | 457.2 | 228.6 | – | 306.7 |
| NPS 20 | 857.2 | 108.0 | 584.2 | 749.3 | 20 × 54.1 | 2" | 622.3 | 508.0 | 247.7 | – | 382.1 |
| NPS 24 | 1041.4 | 139.7 | 692.2 | 901.7 | 20 × 66.8 | 2 1/2" | 749.3 | 609.6 | 292.1 | – | 702.9 |
Show full table · more than 10 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 120.6 | 22.4 | 35.1 | 82.5 | 4 × 22.4 | 3/4" | 38.1 | 21.3 | 60.5 | – | 1.9 |
| NPS 3/4 | 130 | 25.4 | 42.9 | 88.9 | 4 × 22.4 | 3/4" | 44.5 | 26.7 | 69.9 | – | 2.6 |
| NPS 1 | 149.4 | 28.4 | 50.8 | 101.6 | 4 × 25.4 | 7/8" | 52.3 | 33.4 | 73.2 | – | 3.8 |
| NPS 1 1/4 | 158.8 | 28.4 | 63.5 | 111.3 | 4 × 25.4 | 7/8" | 63.5 | 42.2 | 73.2 | – | 4.4 |
| NPS 1 1/2 | 177.8 | 31.8 | 73.2 | 124 | 4 × 28.4 | 1" | 69.9 | 48.3 | 82.6 | – | 6.1 |
| NPS 2 | 215.9 | 38.1 | 91.9 | 165.1 | 8 × 25.4 | 7/8" | 104.6 | 60.3 | 101.6 | – | 11.2 |
| NPS 2 1/2 | 244.3 | 41.1 | 104.6 | 190.5 | 8 × 28.4 | 1" | 124.0 | 73.0 | 104.6 | – | 15.4 |
| NPS 3 | 266.7 | 47.8 | 127 | 203.2 | 8 × 31.8 | 1 1/8" | 133.4 | 88.9 | 117.3 | – | 20.4 |
| NPS 4 | 311.1 | 53.8 | 157.2 | 241.3 | 8 × 35.1 | 1 1/4" | 162.1 | 114.3 | 124.0 | – | 30.6 |
| NPS 5 | 374.6 | 73.2 | 185.7 | 292.1 | 8 × 41.4 | 1 1/2" | 196.9 | 141.3 | 155.4 | – | 58.2 |
| NPS 6 | 393.7 | 82.6 | 215.9 | 317.5 | 12 × 38.1 | 1 3/8" | 228.6 | 168.3 | 171.5 | – | 70.2 |
| NPS 8 | 482.6 | 91.9 | 269.7 | 393.7 | 12 × 44.4 | 1 5/8" | 292.1 | 219.1 | 212.9 | – | 119.8 |
| NPS 10 | 584.2 | 108.0 | 323.9 | 482.6 | 12 × 50.8 | 1 7/8" | 368.3 | 273.1 | 254.0 | – | 209.4 |
| NPS 12 | 673.1 | 124.0 | 381 | 571.5 | 16 × 53.8 | 2" | 450.9 | 323.9 | 282.4 | – | 316 |
| NPS 14 | 749.3 | 133.4 | 412.8 | 635 | 16 × 60.5 | 2 1/4" | 495.3 | 355.6 | 298.5 | – | 416.7 |
| NPS 16 | 825.5 | 146.1 | 469.9 | 704.8 | 16 × 66.8 | 2 1/2" | 552.5 | 406.4 | 311.2 | – | 535.3 |
| NPS 18 | 914.4 | 162.1 | 533.4 | 774.7 | 16 × 73.2 | 2 3/4" | 596.9 | 457.2 | 327.2 | – | 701 |
| NPS 20 | 984.2 | 177.8 | 584.2 | 831.8 | 16 × 79.2 | 3" | 641.4 | 508.0 | 355.6 | – | 865.7 |
| NPS 24 | 1168.4 | 203.2 | 692.2 | 990.6 | 16 × 92.2 | 3 1/2" | 762.0 | 609.6 | 406.4 | – | 1385.9 |
Show full table · more than 10 rows
| NPS | O | tf | R | W | Z × ØI | Stud | X | Ah | Y | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 133.3 | 30.2 | 35.1 | 88.9 | 4 × 22.4 | 3/4" | 42.9 | 21.3 | 73.2 | – | 3.2 |
| NPS 3/4 | 139.7 | 31.8 | 42.9 | 95.2 | 4 × 22.4 | 3/4" | 50.8 | 26.7 | 79.2 | – | 3.9 |
| NPS 1 | 158.8 | 35.1 | 50.8 | 107.9 | 4 × 25.4 | 7/8" | 57.2 | 33.4 | 88.9 | – | 5.6 |
| NPS 1 1/4 | 184.1 | 38.1 | 63.5 | 130.3 | 4 × 28.4 | 1" | 73.2 | 42.2 | 95.3 | – | 8.2 |
| NPS 1 1/2 | 203.2 | 44.5 | 73.2 | 146 | 4 × 31.8 | 1 1/8" | 79.2 | 48.3 | 111.3 | – | 11.6 |
| NPS 2 | 234.9 | 50.8 | 91.9 | 171.4 | 8 × 28.4 | 1" | 95.3 | 60.3 | 127.0 | – | 17.3 |
| NPS 2 1/2 | 266.7 | 57.2 | 104.6 | 196.8 | 8 × 31.8 | 1 1/8" | 114.3 | 73.0 | 142.7 | – | 25.5 |
| NPS 3 | 304.8 | 66.5 | 127 | 228.6 | 8 × 35.1 | 1 1/4" | 133.4 | 88.9 | 168.1 | – | 38.9 |
| NPS 4 | 355.6 | 76.2 | 157.2 | 273.1 | 8 × 41.4 | 1 1/2" | 165.1 | 114.3 | 190.5 | – | 60.1 |
| NPS 5 | 419.1 | 91.9 | 185.7 | 323.8 | 8 × 47.8 | 1 3/4" | 203.2 | 141.3 | 228.6 | – | 100.4 |
| NPS 6 | 482.6 | 108.0 | 215.9 | 368.3 | 8 × 53.8 | 2" | 235.0 | 168.3 | 273.1 | – | 156.6 |
| NPS 8 | 552.4 | 127.0 | 269.7 | 438.1 | 12 × 53.8 | 2" | 304.8 | 219.1 | 317.5 | – | 236.1 |
| NPS 10 | 673.1 | 165.1 | 323.9 | 539.8 | 12 × 66.8 | 2 1/2" | 374.7 | 273.1 | 419.1 | – | 446.9 |
| NPS 12 | 762 | 184.2 | 381 | 619.3 | 12 × 73.2 | 2 3/4" | 441.5 | 323.9 | 463.6 | – | 630.4 |
Pressure test
Pressure test: the standard does not require the manufacturer to pressure test the flange – the flange is tested with the system it is installed in, when the applicable code requires it. Only flanged fittings (elbows, tees with flanges) receive a shell pressure test at 1.5 times the rated pressure at 38 °C. Anyone needing a works pressure test of the flange orders it expressly.
Marking
Marking: the flange carries the manufacturer’s name or mark, the material (ASTM number and grade, e.g. A105 or A182 F316L), the pressure class (150, 300 …), the standard designation B16 (or B16.5), the nominal size NPS, for welding neck flanges the bore or schedule, and the heat or lot number for traceability. The facing type is not part of the mandatory marking – RTJ flanges additionally carry the ring number.
Ordering unambiguously
How to order unambiguously: nominal size, class, type, facing, bore or schedule, material, certificate – for example “welding neck flange NPS 4 Class 150 WN RF, bore SCH 40, ASTM A105, EN 10204 3.1”. Anyone welding on a pipe to EN 10216 gives its outside diameter and wall thickness, because the bore is matched to inch pipe.
Above NPS 24
Above NPS 24, B16.5 no longer applies but ASME B16.47 with its incompatible series A and B (different drilling) – the series belongs in every enquiry.
Further in the topic
In the topic: ASME connecting dimensions · Weld neck flange type 11 to EN 1092-1 · DIN/EN or ASME
Standards: ASME B16.5 profile · Standards world translator · Rule of thumb: Class 150 is not 150 psi
Frequently asked questions
Where do I find the dimensions of a weld neck flange NPS 4 class 150 to ASME B16.5?
The dimension table on this page lists all available sizes to ASME B16.5; the dimensional drawing above it shows the selected size with all dimensions and tolerances and can be printed as a PDF - the data sheet for your size.
Where are the hub diameter A and the bore B of an ASME welding-neck flange measured?
At the end plane of the hub end (B16.5 with B16.25): A across the extended outside surface, B as the inside diameter at the root face. The bevel is 37,5° ± 2,5° to B16.25. B is ordered to the pipe schedule and is not a standard value above NPS 12.
Is Class 150 the same as PN 16?
No. The class is a pressure class to ASME B16.5 whose permissible pressure comes from the pressure–temperature table of the material group; PN is a European nominal pressure. Bolt circle and number of bolts differ too – a Class 150 flange does not fit a PN 16 mating flange.
Why is tf smaller than in older tables?
Since the 2003 edition ASME B16.5 gives the flange thickness without the raised face. Older tables (dimension C) included the 1/16 inch face for Class 150 and 300 – it is the same flange.
Does an ASME weld neck flange fit a pipe to EN 10216?
Only if outside diameter and wall thickness match. The bore B is matched to inch pipe to ASME B36.10M – give the outside diameter and wall thickness of your pipe in the enquiry and we will check the bore.
Enquire about weld neck flanges ASME B16.5
Give NPS, class, facing, bore or schedule, material and certificate – or simply what you have. We will clarify the rest with you.
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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.
Dimensions: as the market supplies them – from manufacturers’ and suppliers’ documentation and from our own product data, checked against ASME B16.5-2025; weights calculated by Zickwolff (nominal dimensions, 7.85 kg/dm³); dimension letters to ASME B16.5-2025 Table 8. Tolerances: tolerances from manufacturers’ and suppliers’ documentation, where these give none ASME B16.5-2025 section 7. No liability – the standard in force governs.