Flanges · ASME B16.5
Lap joint flange: dimensions and dimensional drawing to ASME B16.5
All dimensions of the lap joint flange to ASME B16.5 in one table, the dimensional drawing of your size above it – available from stock or to order. Lap joint flanges to ASME B16.5 (LJ) from NPS 1/2 to 24 in pressure classes 150 to 2500 – the flange sits loose on a stub end (ASME B16.9) welded to the pipe and turns freely. 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, length through hub Y, bore B1 and radius r – 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 (Class 2500 in our sources up to NPS 12)
- Facing
- none on the flange – the seal is made on the stub end (ASME B16.9)
- Dimension letters
- to ASME B16.5: O, tf, W, Z × ØI, X, Y, B1, r
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 lap joint 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 23.9 mm (0.9 in), Sealing face on the stub end (ASME B16.9), weight 5.5 kg.
Direct link to this size: https://www.zickwolff.de/wissen/en/flanges/lap-joint-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.
Lap joint 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 | 5.5 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 | 23.9 mm (0.9 in) | market dimension |
| sealing face | ||
| Sealing face | on the stub end (ASME B16.9) – the lap joint flange has no raised face (ASME B16.5 6.4.3) | statement of the standard |
| hub and welding end | ||
| hub diameter X | 134.9 mm (5.3 in) | market dimension |
| length through hub Y | 33.3 mm (1.3 in) | market dimension |
| bore (through-bore) B1 | 116.8 mm (4.6 in) | market dimension |
| corner radius r | 11.2 mm (0.4 in) | market dimension |
| Matching pipe | outside diameter Ah 114.3 mm to ASME B36.10M – the stub end is welded to the pipe | assignment |
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
- thicker than the slip-on flange of the same size – measure the full plate, the lap joint flange has no raised face
- hub diameter X
- measure at the transition to the flange plate, where the hub is thickest
- length through hub Y
- from the flange face to the end of the hub – the lap joint flange has no raised face. Many manufacturers make it to the slip-on length, check the drawing of the delivered flange
- bore (through-bore) B1
- bore B1 for the stub end – larger than on the slip-on flange, the flange turns freely on the stub end
- corner radius r
- radius at the bore B1 on the face side – matches the fillet of the stub end
- weight
- calculated by Zickwolff from the nominal dimensions at 7.85 kg/dm³ – guide value, not a standard value
Tolerances (limit deviations): what range the standard permits
For each dimension the permissible range is given – to ASME B16.5, for O, X and Y to the manufacturers’ values, because the standard does not limit these dimensions of the lap joint flange. 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 B1 | 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 (9 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 B1 – perpendicularity of the face to the bore B1 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
- 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
- length through hub – length through hub up to NPS 18
- bore (through-bore) – bore 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, the hub diameter X and the length through hub Y of the lap joint flange the standard sets no tolerance – the manufacturers’ values apply there. The perpendicularity of the face to the bore B1 is not in the tables – it is given according to the standard. The lap joint flange has no raised face – the seal is made on the stub end.
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
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, the full plate
- W – bolt circle diameter
- Z × ØI – number and diameter of bolt holes
- X – hub diameter at the plate
- Y – length through hub, from the flange face
- B1 – bore for the stub end
- r – radius at the bore B1 on the face side
The lap joint flange has no raised face R – the sealing face is the lap of the stub end.
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: the full plate from the flange face to the back – the lap joint flange has no raised face (ASME B16.5 6.4.3). In small sizes it is slightly thicker than the slip-on flange of the same size. The bore B1 is larger than on the slip-on flange and rounded with the radius r on the face side – it matches the fillet of the stub end.
- Stub end: the seal is made on the stub end (ASME B16.9), which is welded to the pipe – the lap joint flange only presses it on. After machining, the lap of the stub end must not be thinner than the nominal wall thickness of the pipe (ASME B16.5 6.4.3.1). The gasket sits on the lap, its dimensions follow the stub end, not the flange.
- Hub: the hub diameter X is measured at the transition to the plate. The hub may be straight or tapered – at most 7° to ASME B16.5. The length through hub Y runs from the flange face to the end of the hub.
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 and Y from the flange face (no raised face), weight calculated by Zickwolff (7.85 kg/dm³).
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 (lap joint) – thicker than the slip-on flange of the same size – measure the full plate, there is no raised face on the loose flange
- 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)
- Y
- length through hub Y (lap joint) – nominal lap joint length – many manufacturers make it to the slip-on length, check the drawing of the delivered flange
- r
- radius r – radius at the bore on the face side – matches the fillet of the stub end
- G (kg)
- weight G – catalogue value approx., standard bore – trade figure, not a standard value
Show full table · more than 20 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 88.9 | 11.2 | 60.5 | 4 × 15.7 | 1/2" | 30.2 | 15.7 | 22.9 | 3.0 | 0.45 |
| NPS 3/4 | 98.6 | 12.7 | 69.9 | 4 × 15.7 | 1/2" | 38.1 | 15.7 | 28.2 | 3.0 | 0.63 |
| NPS 1 | 108 | 14.2 | 79.2 | 4 × 15.7 | 1/2" | 49.3 | 17.5 | 35.1 | 3.0 | 0.85 |
| NPS 1 1/4 | 117.3 | 15.7 | 88.9 | 4 × 15.7 | 1/2" | 58.7 | 20.6 | 43.7 | 4.8 | 1.1 |
| NPS 1 1/2 | 127 | 17.5 | 98.6 | 4 × 15.7 | 1/2" | 65.0 | 22.4 | 50.0 | 6.4 | 1.4 |
| NPS 2 | 152.4 | 19.1 | 120.7 | 4 × 19.1 | 5/8" | 77.7 | 25.4 | 62.5 | 7.9 | 2.2 |
| NPS 2 1/2 | 177.8 | 22.4 | 139.7 | 4 × 19.1 | 5/8" | 90.4 | 28.4 | 75.4 | 7.9 | 3.5 |
| NPS 3 | 190.5 | 23.9 | 152.4 | 4 × 19.1 | 5/8" | 108.0 | 30.2 | 91.4 | 9.7 | 4 |
| NPS 3 1/2 | 215.9 | 23.9 | 177.8 | 8 × 19.1 | 5/8" | 122.2 | 31.8 | 104.1 | 9.7 | 5 |
| NPS 4 | 228.6 | 23.9 | 190.5 | 8 × 19.1 | 5/8" | 134.9 | 33.3 | 116.8 | 11.2 | 5.5 |
| NPS 5 | 254 | 23.9 | 215.9 | 8 × 22.4 | 3/4" | 163.6 | 36.6 | 144.5 | 11.2 | 6.3 |
| NPS 6 | 279.4 | 25.4 | 241.3 | 8 × 22.4 | 3/4" | 192.0 | 39.6 | 171.5 | 12.7 | 7.6 |
| NPS 8 | 342.9 | 28.4 | 298.5 | 8 × 22.4 | 3/4" | 246.1 | 44.5 | 222.3 | 12.7 | 12.3 |
| NPS 10 | 406.4 | 30.2 | 362 | 12 × 25.4 | 7/8" | 304.8 | 49.3 | 277.4 | 12.7 | 16.9 |
| NPS 12 | 482.6 | 31.8 | 431.8 | 12 × 25.4 | 7/8" | 365.3 | 55.6 | 328.2 | 12.7 | 26.8 |
| NPS 14 | 533.4 | 35.1 | 476.3 | 12 × 28.4 | 1" | 400.1 | 79.2 | 360.2 | 12.7 | 39.6 |
| NPS 16 | 596.9 | 36.6 | 539.8 | 16 × 28.4 | 1" | 457.2 | 87.4 | 411.2 | 12.7 | 51.8 |
| NPS 18 | 635 | 39.6 | 577.9 | 16 × 31.8 | 1 1/8" | 505.0 | 96.8 | 462.3 | 12.7 | 56.9 |
| NPS 20 | 698.5 | 42.9 | 635 | 20 × 31.8 | 1 1/8" | 558.8 | 103.1 | 514.4 | 12.7 | 71.4 |
| NPS 22 | 749.3 | 46.0 | 692.1 | 20 × 35.1 | 1 1/4" | 610.0 | 108.0 | 565.2 | 12.7 | 81.8 |
| NPS 24 | 812.8 | 47.8 | 749.3 | 20 × 35.1 | 1 1/4" | 663.4 | 111.3 | 616.0 | 12.7 | 99.3 |
Show full table · more than 20 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.2 | 14.2 | 66.5 | 4 × 15.7 | 1/2" | 38.1 | 22.4 | 22.9 | 3.0 | 0.71 |
| NPS 3/4 | 117.3 | 15.7 | 82.5 | 4 × 19 | 5/8" | 47.8 | 25.4 | 28.2 | 3.0 | 1.2 |
| NPS 1 | 123.9 | 17.5 | 88.9 | 4 × 19 | 5/8" | 53.8 | 26.9 | 35.1 | 3.0 | 1.5 |
| NPS 1 1/4 | 133.3 | 19.1 | 98.5 | 4 × 19 | 5/8" | 63.5 | 26.9 | 43.7 | 4.8 | 1.8 |
| NPS 1 1/2 | 155.4 | 20.6 | 114.3 | 4 × 22.3 | 3/4" | 69.9 | 30.2 | 50.0 | 6.4 | 2.6 |
| NPS 2 | 165.1 | 22.4 | 127 | 8 × 19 | 5/8" | 84.1 | 33.3 | 62.5 | 7.9 | 3 |
| NPS 2 1/2 | 190.5 | 25.4 | 149.3 | 8 × 22.3 | 3/4" | 100.1 | 38.1 | 75.4 | 7.9 | 4.5 |
| NPS 3 | 209.5 | 28.4 | 168.1 | 8 × 22.3 | 3/4" | 117.3 | 42.9 | 91.4 | 9.7 | 6 |
| NPS 3 1/2 | 228.6 | 30.2 | 184.1 | 8 × 22.3 | 3/4" | 133.4 | 44.5 | 104.1 | 9.7 | 7.6 |
| NPS 4 | 254 | 31.8 | 200.1 | 8 × 22.3 | 3/4" | 146.1 | 47.8 | 116.8 | 11.2 | 10 |
| NPS 5 | 279.4 | 35.1 | 234.9 | 8 × 22.3 | 3/4" | 177.8 | 50.8 | 144.5 | 11.2 | 12.6 |
| NPS 6 | 317.5 | 36.6 | 269.7 | 12 × 22.3 | 3/4" | 206.2 | 52.3 | 171.5 | 12.7 | 16 |
| NPS 8 | 381 | 41.1 | 330.2 | 12 × 25.4 | 7/8" | 260.4 | 62.0 | 222.3 | 12.7 | 24.7 |
| NPS 10 | 444.5 | 47.8 | 387.3 | 16 × 28.4 | 1" | 320.5 | 95.3 | 277.4 | 12.7 | 39.3 |
| NPS 12 | 520.7 | 50.8 | 450.8 | 16 × 31.7 | 1 1/8" | 374.7 | 101.6 | 328.2 | 12.7 | 56.4 |
| NPS 14 | 584.2 | 53.8 | 514.3 | 20 × 31.7 | 1 1/8" | 425.5 | 111.3 | 360.2 | 12.7 | 81.7 |
| NPS 16 | 647.7 | 57.2 | 571.5 | 20 × 35 | 1 1/4" | 482.6 | 120.7 | 411.2 | 12.7 | 104.7 |
| NPS 18 | 711.2 | 60.5 | 628.6 | 24 × 35 | 1 1/4" | 533.4 | 130.0 | 462.3 | 12.7 | 128.3 |
| NPS 20 | 774.7 | 63.5 | 685.8 | 24 × 35 | 1 1/4" | 587.2 | 139.7 | 514.4 | 12.7 | 157.5 |
| NPS 22 | 838.2 | 66.8 | 742.9 | 24 × 41.4 | 1 1/2" | 641.4 | 145.0 | 565.2 | 12.7 | 185.2 |
| NPS 24 | 914.4 | 69.9 | 812.8 | 24 × 41.1 | 1 1/2" | 701.5 | 152.4 | 616.0 | 12.7 | 236.6 |
Show full table · more than 20 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.3 | 14.2 | 66.5 | 4 × 16.0 | 0.505" | 38.1 | 22.4 | 22.9 | 3.0 | 0.71 |
| NPS 3/4 | 117.3 | 15.7 | 82.6 | 4 × 19.1 | 0.625" | 47.8 | 25.4 | 28.2 | 3.0 | 1.2 |
| NPS 1 | 124.0 | 17.5 | 88.9 | 4 × 19.1 | 0.625" | 53.8 | 26.9 | 35.1 | 3.0 | 1.5 |
| NPS 1 1/4 | 133.4 | 20.6 | 98.6 | 4 × 19.1 | 0.625" | 63.5 | 28.4 | 43.7 | 4.8 | 1.9 |
| NPS 1 1/2 | 155.4 | 22.4 | 114.3 | 4 × 22.4 | 0.755" | 69.9 | 31.8 | 50.0 | 6.4 | 2.9 |
| NPS 2 | 165.1 | 25.4 | 127.0 | 8 × 19.1 | 0.625" | 84.1 | 36.6 | 62.5 | 7.9 | 3.4 |
| NPS 2 1/2 | 190.5 | 28.4 | 149.4 | 8 × 22.4 | 0.755" | 100.1 | 41.1 | 75.4 | 7.9 | 5 |
| NPS 3 | 209.6 | 31.8 | 168.1 | 8 × 22.4 | 0.755" | 117.3 | 46.0 | 91.4 | 9.7 | 6.7 |
| NPS 3 1/2 | 228.6 | 35.1 | 184.2 | 8 × 25.4 | 0.875" | 133.4 | 49.3 | 104.1 | 9.7 | 8.5 |
| NPS 4 | 254.0 | 35.1 | 200.2 | 8 × 25.4 | 0.875" | 146.1 | 50.8 | 116.8 | 11.2 | 10.6 |
| NPS 5 | 279.4 | 38.1 | 235.0 | 8 × 25.4 | 0.875" | 177.8 | 53.8 | 144.5 | 11.2 | 13.3 |
| NPS 6 | 317.5 | 41.1 | 269.7 | 12 × 25.4 | 0.875" | 206.2 | 57.2 | 171.5 | 12.7 | 17.4 |
| NPS 8 | 381.0 | 47.8 | 330.2 | 12 × 28.4 | 0.995" | 260.4 | 68.3 | 222.3 | 12.7 | 27.7 |
| NPS 10 | 444.5 | 53.8 | 387.4 | 16 × 31.8 | 1.125" | 320.5 | 101.6 | 277.4 | 12.7 | 42.2 |
| NPS 12 | 520.7 | 57.2 | 450.9 | 16 × 35.1 | 1.255" | 374.7 | 108.0 | 328.2 | 12.7 | 60.9 |
| NPS 14 | 584.2 | 60.5 | 514.4 | 20 × 35.1 | 1.255" | 425.5 | 117.3 | 360.2 | 12.7 | 87.7 |
| NPS 16 | 647.7 | 63.5 | 571.5 | 20 × 38.1 | 1.375" | 482.6 | 127.0 | 411.2 | 12.7 | 111.7 |
| NPS 18 | 711.2 | 66.5 | 628.7 | 24 × 38.1 | 1.375" | 533.4 | 136.7 | 462.3 | 12.7 | 136.1 |
| NPS 20 | 774.7 | 69.9 | 685.8 | 24 × 41.1 | 1.495" | 587.2 | 146.1 | 514.4 | 12.7 | 164.8 |
| NPS 22 | 838.2 | 73.2 | 743.0 | 24 × 44.5 | 1.625" | 641.4 | 152.4 | 565.2 | 12.7 | 196.4 |
| NPS 24 | 914.4 | 76.2 | 812.8 | 24 × 47.8 | 1.755" | 701.5 | 158.8 | 616.0 | 12.7 | 246.1 |
Show full table · more than 20 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.3 | 14.2 | 66.5 | 4 × 15.7 | 1/2" | 38.1 | 22.4 | 22.9 | 3.0 | 0.71 |
| NPS 3/4 | 117.3 | 15.7 | 82.6 | 4 × 19.1 | 5/8" | 47.8 | 25.4 | 28.2 | 3.0 | 1.2 |
| NPS 1 | 124 | 17.5 | 88.9 | 4 × 19.1 | 5/8" | 53.8 | 26.9 | 35.1 | 3.0 | 1.5 |
| NPS 1 1/4 | 133.4 | 20.6 | 98.6 | 4 × 19.1 | 5/8" | 63.5 | 28.4 | 43.7 | 4.8 | 1.9 |
| NPS 1 1/2 | 155.4 | 22.4 | 114.3 | 4 × 22.4 | 3/4" | 69.9 | 31.8 | 50.0 | 6.4 | 2.9 |
| NPS 2 | 165.1 | 25.4 | 127 | 8 × 19.1 | 5/8" | 84.1 | 36.6 | 62.5 | 7.9 | 3.4 |
| NPS 2 1/2 | 190.5 | 28.4 | 149.4 | 8 × 22.4 | 3/4" | 100.1 | 41.1 | 75.4 | 7.9 | 5 |
| NPS 3 | 209.6 | 31.8 | 168.1 | 8 × 22.4 | 3/4" | 117.3 | 46.0 | 91.4 | 9.7 | 6.7 |
| NPS 3 1/2 | 228.6 | 35.1 | 184.2 | 8 × 25.4 | 7/8" | 133.4 | 49.3 | 104.1 | 9.7 | 8.5 |
| NPS 4 | 273.1 | 38.1 | 215.9 | 8 × 25.4 | 7/8" | 152.4 | 53.8 | 116.8 | 11.2 | 14 |
| NPS 5 | 330.2 | 44.5 | 266.7 | 8 × 28.4 | 1" | 189.0 | 60.5 | 144.5 | 11.2 | 23.9 |
| NPS 6 | 355.6 | 47.8 | 292.1 | 12 × 28.4 | 1" | 222.3 | 66.5 | 171.5 | 12.7 | 28.1 |
| NPS 8 | 419.1 | 55.6 | 349.3 | 12 × 31.8 | 1 1/8" | 273.1 | 76.2 | 222.3 | 12.7 | 42.3 |
| NPS 10 | 508 | 63.5 | 431.8 | 16 × 35.1 | 1 1/4" | 342.9 | 111.3 | 277.4 | 12.7 | 75.2 |
| NPS 12 | 558.8 | 66.5 | 489 | 20 × 35.1 | 1 1/4" | 400.1 | 117.3 | 328.2 | 12.7 | 90.2 |
| NPS 14 | 603.3 | 69.9 | 527 | 20 × 38.1 | 1 3/8" | 431.8 | 127.0 | 360.2 | 12.7 | 108.4 |
| NPS 16 | 685.8 | 76.2 | 603.3 | 20 × 41.1 | 1 1/2" | 495.3 | 139.7 | 411.2 | 12.7 | 155.5 |
| NPS 18 | 743 | 82.6 | 654.1 | 20 × 44.5 | 1 5/8" | 546.1 | 152.4 | 462.3 | 12.7 | 188.5 |
| NPS 20 | 812.8 | 88.9 | 723.9 | 24 × 44.5 | 1 5/8" | 609.6 | 165.1 | 514.4 | 12.7 | 241.3 |
| NPS 22 | 869.9 | 95.3 | 778 | 24 × 44.4 | 1 5/8" | 663.0 | 174.8 | 565.2 | 12.7 | 288 |
| NPS 24 | 939.8 | 101.6 | 838.2 | 24 × 50.8 | 1 7/8" | 717.6 | 184.2 | 616.0 | 12.7 | 345.8 |
Show full table · more than 10 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 120.6 | 22.4 | 82.5 | 4 × 22.4 | 3/4" | 38.1 | 31.8 | 22.9 | 3.0 | 1.7 |
| NPS 3/4 | 130 | 25.4 | 88.9 | 4 × 22.4 | 3/4" | 44.5 | 35.1 | 28.2 | 3.0 | 2.3 |
| NPS 1 | 149.4 | 28.4 | 101.6 | 4 × 25.4 | 7/8" | 52.3 | 41.1 | 35.1 | 3.0 | 3.4 |
| NPS 1 1/4 | 158.8 | 28.4 | 111.3 | 4 × 25.4 | 7/8" | 63.5 | 41.1 | 43.7 | 4.8 | 3.8 |
| NPS 1 1/2 | 177.8 | 31.8 | 124 | 4 × 28.4 | 1" | 69.9 | 44.5 | 50.0 | 6.4 | 5.3 |
| NPS 2 | 215.9 | 38.1 | 165.1 | 8 × 25.4 | 7/8" | 104.6 | 57.2 | 62.5 | 7.9 | 9.6 |
| NPS 2 1/2 | 244.3 | 41.1 | 190.5 | 8 × 28.4 | 1" | 124.0 | 63.5 | 75.4 | 7.9 | 13.4 |
| NPS 3 | 241.3 | 38.1 | 190.5 | 8 × 25.4 | 7/8" | 127.0 | 53.8 | 91.4 | 9.7 | 11.3 |
| NPS 4 | 292.1 | 44.5 | 234.9 | 8 × 31.8 | 1 1/8" | 158.8 | 69.9 | 116.8 | 11.2 | 19.3 |
| NPS 5 | 349.2 | 50.8 | 279.4 | 8 × 35.1 | 1 1/4" | 190.5 | 79.2 | 144.5 | 11.2 | 31.3 |
| NPS 6 | 381 | 55.6 | 317.5 | 12 × 31.8 | 1 1/8" | 235.0 | 85.9 | 171.5 | 12.7 | 40.3 |
| NPS 8 | 469.9 | 63.5 | 393.7 | 12 × 38.1 | 1 3/8" | 298.5 | 114.3 | 222.3 | 12.7 | 72.7 |
| NPS 10 | 546.1 | 69.9 | 469.9 | 16 × 38.1 | 1 3/8" | 368.3 | 127.0 | 277.4 | 12.7 | 106 |
| NPS 12 | 609.6 | 79.2 | 533.4 | 20 × 38.1 | 1 3/8" | 419.1 | 142.7 | 328.2 | 12.7 | 141.3 |
| NPS 14 | 641.3 | 85.9 | 558.8 | 20 × 41.4 | 1 1/2" | 450.9 | 155.4 | 360.2 | 12.7 | 162.5 |
| NPS 16 | 704.8 | 88.9 | 615.9 | 20 × 44.4 | 1 5/8" | 508.0 | 165.1 | 411.2 | 12.7 | 199.8 |
| NPS 18 | 787.4 | 101.6 | 685.8 | 20 × 50.8 | 1 7/8" | 565.2 | 190.5 | 462.3 | 12.7 | 280.1 |
| NPS 20 | 857.2 | 108.0 | 749.3 | 20 × 54.1 | 2" | 622.3 | 209.6 | 514.4 | 12.7 | 350.9 |
| NPS 24 | 1041.4 | 139.7 | 901.7 | 20 × 66.8 | 2 1/2" | 749.3 | 266.7 | 616.0 | 12.7 | 672.9 |
Show full table · more than 10 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 120.6 | 22.4 | 82.5 | 4 × 22.4 | 3/4" | 38.1 | 31.8 | 22.9 | 3.0 | 1.7 |
| NPS 3/4 | 130 | 25.4 | 88.9 | 4 × 22.4 | 3/4" | 44.5 | 35.1 | 28.2 | 3.0 | 2.3 |
| NPS 1 | 149.4 | 28.4 | 101.6 | 4 × 25.4 | 7/8" | 52.3 | 41.1 | 35.1 | 3.0 | 3.4 |
| NPS 1 1/4 | 158.8 | 28.4 | 111.3 | 4 × 25.4 | 7/8" | 63.5 | 41.1 | 43.7 | 4.8 | 3.8 |
| NPS 1 1/2 | 177.8 | 31.8 | 124 | 4 × 28.4 | 1" | 69.9 | 44.5 | 50.0 | 6.4 | 5.3 |
| NPS 2 | 215.9 | 38.1 | 165.1 | 8 × 25.4 | 7/8" | 104.6 | 57.2 | 62.5 | 7.9 | 9.6 |
| NPS 2 1/2 | 244.3 | 41.1 | 190.5 | 8 × 28.4 | 1" | 124.0 | 63.5 | 75.4 | 7.9 | 13.4 |
| NPS 3 | 266.7 | 47.8 | 203.2 | 8 × 31.8 | 1 1/8" | 133.4 | 73.2 | 91.4 | 9.7 | 17.6 |
| NPS 4 | 311.1 | 53.8 | 241.3 | 8 × 35.1 | 1 1/4" | 162.1 | 90.4 | 116.8 | 11.2 | 27.2 |
| NPS 5 | 374.6 | 73.2 | 292.1 | 8 × 41.4 | 1 1/2" | 196.9 | 104.6 | 144.5 | 11.2 | 51.2 |
| NPS 6 | 393.7 | 82.6 | 317.5 | 12 × 38.1 | 1 3/8" | 228.6 | 119.1 | 171.5 | 12.7 | 60.2 |
| NPS 8 | 482.6 | 91.9 | 393.7 | 12 × 44.4 | 1 5/8" | 292.1 | 142.7 | 222.3 | 12.7 | 101.8 |
| NPS 10 | 584.2 | 108.0 | 482.6 | 12 × 50.8 | 1 7/8" | 368.3 | 177.8 | 277.4 | 12.7 | 180.7 |
| NPS 12 | 673.1 | 124.0 | 571.5 | 16 × 53.8 | 2" | 450.9 | 218.9 | 328.2 | 12.7 | 284.5 |
| NPS 14 | 749.3 | 133.4 | 635 | 16 × 60.5 | 2 1/4" | 495.3 | 241.3 | 360.2 | 12.7 | 383.8 |
| NPS 16 | 825.5 | 146.1 | 704.8 | 16 × 66.8 | 2 1/2" | 552.5 | 260.4 | 411.2 | 12.7 | 493.2 |
| NPS 18 | 914.4 | 162.1 | 774.7 | 16 × 73.2 | 2 3/4" | 596.9 | 276.4 | 462.3 | 12.7 | 636.8 |
| NPS 20 | 984.2 | 177.8 | 831.8 | 16 × 79.2 | 3" | 641.4 | 292.1 | 514.4 | 12.7 | 765.2 |
| NPS 24 | 1168.4 | 203.2 | 990.6 | 16 × 92.2 | 3 1/2" | 762.0 | 330.2 | 616.0 | 12.7 | 1222 |
Show full table · more than 10 rows
| NPS | O | tf | W | Z × ØI | Stud | X | Y | B1 | r | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 133.3 | 30.2 | 88.9 | 4 × 22.4 | 3/4" | 42.9 | 39.6 | 22.9 | 3.0 | 2.9 |
| NPS 3/4 | 139.7 | 31.8 | 95.2 | 4 × 22.4 | 3/4" | 50.8 | 42.9 | 28.2 | 3.0 | 3.4 |
| NPS 1 | 158.8 | 35.1 | 107.9 | 4 × 25.4 | 7/8" | 57.2 | 47.8 | 35.1 | 3.0 | 4.8 |
| NPS 1 1/4 | 184.1 | 38.1 | 130.3 | 4 × 28.4 | 1" | 73.2 | 52.3 | 43.7 | 4.8 | 7.1 |
| NPS 1 1/2 | 203.2 | 44.5 | 146 | 4 × 31.8 | 1 1/8" | 79.2 | 60.5 | 50.0 | 6.4 | 9.9 |
| NPS 2 | 234.9 | 50.8 | 171.4 | 8 × 28.4 | 1" | 95.3 | 69.9 | 62.5 | 7.9 | 14.6 |
| NPS 2 1/2 | 266.7 | 57.2 | 196.8 | 8 × 31.8 | 1 1/8" | 114.3 | 79.2 | 75.4 | 7.9 | 21.2 |
| NPS 3 | 304.8 | 66.5 | 228.6 | 8 × 35.1 | 1 1/4" | 133.4 | 91.9 | 91.4 | 9.7 | 32.1 |
| NPS 4 | 355.6 | 76.2 | 273.1 | 8 × 41.4 | 1 1/2" | 165.1 | 108.0 | 116.8 | 11.2 | 49.2 |
| NPS 5 | 419.1 | 91.9 | 323.8 | 8 × 47.8 | 1 3/4" | 203.2 | 130.0 | 144.5 | 11.2 | 82.1 |
| NPS 6 | 482.6 | 108.0 | 368.3 | 8 × 53.8 | 2" | 235.0 | 152.4 | 171.5 | 12.7 | 127.1 |
| NPS 8 | 552.4 | 127.0 | 438.1 | 12 × 53.8 | 2" | 304.8 | 177.8 | 222.3 | 12.7 | 186.7 |
| NPS 10 | 673.1 | 165.1 | 539.8 | 12 × 66.8 | 2 1/2" | 374.7 | 228.6 | 277.4 | 12.7 | 353.2 |
| NPS 12 | 762 | 184.2 | 619.3 | 12 × 73.2 | 2 3/4" | 441.5 | 254.0 | 328.2 | 12.7 | 501.6 |
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: lap joint flange and stub end separately – for example “lap joint flange NPS 4 Class 150 LJ, ASTM A105, EN 10204 3.1” and with it “stub end NPS 4 SCH 10S to ASME B16.9, material as the pipe”. The flange does not touch the medium, its material follows the class and the bolting; stub end and pipe determine the material in contact with the medium.
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 · Loose flanges type 02 and 04 to EN 1092-1 · Slip-on flange ASME B16.5 · Weld neck flange ASME B16.5 · 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 lap joint 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.
What is a lap joint flange for?
The lap joint flange does not touch the medium and turns freely on the stub end. The bolt holes can therefore be aligned during assembly, and on stainless or special-alloy lines a simple material is enough for the flange – only the stub end and the pipe are made of the expensive material.
Is the ASME lap joint flange the same as type 02 to EN 1092-1?
The design is the same: a loose flange on a collar. Connecting dimensions, bore and collar follow different standards, however – a lap joint flange to ASME B16.5 fits a stub end to ASME B16.9, not a weld-on collar type 32 to EN 1092-1.
Why does the lap joint flange have no raised face?
Because it does not seal. ASME B16.5 specifies a flat face for lap joint flanges – the gasket sits on the lap of the stub end, the flange only presses the stub end on.
Enquire about lap joint flanges ASME B16.5
Give NPS, class, material of flange and stub end and the 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.