Flanges · ASME B16.5
Socket weld flange: dimensions and dimensional drawing to ASME B16.5
All dimensions of the socket weld flange to ASME B16.5 in one table, the dimensional drawing of your size above it – available from stock or to order. Socket weld flanges to ASME B16.5 (SW) from NPS 1/2 to 3 in pressure classes 150 to 1500 – the pipe is inserted into the socket and welded outside with a fillet weld. Choose the class and nominal pipe size: drawing and dimension table show outside diameter O, flange thickness tf, raised face R, bolt circle W, bolt holes, hub X, length through hub Y, socket bore B2, socket depth D and through bore B – in millimetres, with the inch value in brackets, with the clearance in the socket and with the tolerances.
- Standard
- ASME B16.5-2025 – dimensions from manufacturers’ and suppliers’ documentation, checked against the standard
- Sizes
- NPS 1/2 to 3 (standardised up to NPS 3 only) · Class 150, 300, 400, 600, 900, 1500
- Facing
- raised face RF (standard) – RTJ with ring groove on request
- Dimension letters
- to ASME B16.5: O, tf, R, W, Z × ØI, X, Y, B2, D, 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 1 in the field “Nominal pipe size (NPS)”. The dimensional drawing immediately shows every dimension of the socket weld flange with tolerances, the table below all sizes. “Print this size as PDF” takes the drawing with you.
Example NPS 1 Class 150: outside diameter O 108 mm (4.3 in), bolt circle diameter W 79.2 mm, bolt holes Z × I 4 × ⌀15.7 mm, stud bolt 1/2", flange thickness tf 12.7 mm (0.5 in), raised face diameter R 50.8 mm, weight 0.8 kg.
Direct link to this size: https://www.zickwolff.de/wissen/en/flanges/socket-weld-flange-asme-b16-5/?class=150&nps=1
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.
Socket weld flange · ASME B16.5 · NPS 1 · 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 1 | market dimension |
| Pressure class | Class 150 | market dimension |
| weight | 0.8 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 | 108 mm (4.3 in) | market dimension |
| bolt circle diameter W | 79.2 mm | market dimension |
| bolt holes Z × I | 4 × ⌀15.7 mm | market dimension |
| stud bolt | 1/2" | market dimension |
| flange thickness tf | 12.7 mm (0.5 in) | market dimension |
| sealing face | ||
| raised face diameter R | 50.8 mm | market dimension |
| raised face height (RF) | 1.5 mm | market dimension |
| hub and welding end | ||
| hub diameter X | 49.3 mm (1.9 in) | market dimension |
| length through hub Y | 15.7 mm (0.6 in) | market dimension |
| socket bore B2 | 34.5 mm (1.4 in) | market dimension |
| socket depth D | 12.7 mm (0.5 in) | market dimension |
| through bore B | 26.7 mm (1.1 in) | market dimension |
| Matching pipe | outside diameter Ah 33.4 mm to ASME B36.10M | assignment |
| Clearance in the socket (calculated) | 1.1 mm on the diameter – calculated from B2 and Ah | 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
- length through hub Y
- from the flange face without the raised face to the end of the hub – the overall height without the face
- socket bore B2
- inside diameter of the socket – pipe outside diameter plus clearance, measure at the socket mouth
- socket depth D
- depth of the socket from the mouth at the end of the hub to the shoulder
- through bore B
- through bore behind the socket shoulder – standard wall (Class 150/300) or extra strong (from Class 600) per catalogue, otherwise an order item
- 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.
Tolerances (limit deviations): what range the standard permits
For each dimension the permissible range is given – to ASME B16.5, for O, X, Y and D to the manufacturers’ values, because the standard does not limit these dimensions of the socket weld 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 0.8 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 (12 entries)
- spacing of adjacent bolt holes – bolt hole to bolt hole
- concentricity of bolt circle and facing – concentricity bolt circle to facing up to NPS 2 1/2
- 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
- length through hub – length through hub up to NPS 18
- socket bore – socket bore B2 (counterbore) NPS 1/2 to 3
- socket depth – socket depth D
- through bore – through bore B 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 3, Class 150 to 1500 – 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, the length through hub Y and the socket depth D of the socket weld flange the standard sets no tolerance – the manufacturers’ values apply there. The socket bore B2, the through bore B and the perpendicularity of the face to the bore B are not in the tables – they are 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.
Not in the dimensional drawing: NPS 3 Class 900, NPS 3 Class 1500 – not covered by ASME B16.5, manufacturer size only
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 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
- Y – length through hub, from the flange face without raised face
- B2 – socket bore – pipe outside diameter plus clearance
- D – socket depth to the shoulder
- B – through bore behind the shoulder
This page follows the letters of the standard: B2 is the socket, B the through bore – catalogues often write it the other way round. There is no welding end Ah: the weld is made outside at the end of the hub.
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.
- Socket: the socket bore B2 is the pipe outside diameter plus clearance and is measured at the mouth; its tolerance is set by the standard (ASME B16.5 7.7.3). The socket depth D runs from the mouth at the end of the hub to the shoulder. Behind it is the through bore B – it follows the wall thickness of the pipe and, where the catalogue does not give it, is a purchase specification. On assembly the pipe is withdrawn about 1.5 mm from the shoulder before welding.
- 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 without the raised face to the end of the hub.
- 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, B2 socket, D socket depth, B through bore, 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 – 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)
- Y
- length through hub Y – from the back face of the flange plate to the end of the hub – the whole flange height without the raised face
- B2
- through bore B2 – bore behind the socket shoulder, printed for standard wall (Class 150/300) and extra strong (Class 600) – otherwise an order item
- D
- socket depth D – depth of the socket from the mouth to the shoulder – the pipe is withdrawn about 1.5 mm before welding (gap)
- B
- socket bore B – inside diameter of the socket – pipe outside diameter plus clearance, measure at the socket mouth
- G (kg)
- weight G – catalogue value approx., standard bore – trade figure, not a standard value
| NPS | O | tf | R | W | Z × ØI | Stud | X | Y | B2 | D | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 88.9 | 9.7 | 35.1 | 60.5 | 4 × 15.7 | 1/2" | 30.2 | 14.2 | 22.4 | 9.7 | 15.7 | 0.41 |
| NPS 3/4 | 98.6 | 11.2 | 42.9 | 69.9 | 4 × 15.7 | 1/2" | 38.1 | 14.2 | 27.7 | 11.2 | 20.8 | 0.58 |
| NPS 1 | 108 | 12.7 | 50.8 | 79.2 | 4 × 15.7 | 1/2" | 49.3 | 15.7 | 34.5 | 12.7 | 26.7 | 0.79 |
| NPS 1 1/4 | 117.3 | 14.2 | 63.5 | 88.9 | 4 × 15.7 | 1/2" | 58.7 | 19.1 | 43.2 | 14.2 | 35.1 | 1 |
| NPS 1 1/2 | 127 | 15.7 | 73.2 | 98.6 | 4 × 15.7 | 1/2" | 65.0 | 20.6 | 49.5 | 15.7 | 40.9 | 1.3 |
| NPS 2 | 152.4 | 17.5 | 91.9 | 120.7 | 4 × 19.1 | 5/8" | 77.7 | 23.9 | 62.0 | 17.5 | 52.6 | 2.1 |
| NPS 2 1/2 | 177.8 | 20.6 | 104.6 | 139.7 | 4 × 19.1 | 5/8" | 90.4 | 26.9 | 74.7 | 19.1 | 62.7 | 3.4 |
| NPS 3 | 190.5 | 22.4 | 127 | 152.4 | 4 × 19.1 | 5/8" | 108.0 | 28.4 | 90.7 | 20.6 | 78.0 | 4 |
| NPS | O | tf | R | W | Z × ØI | Stud | X | Y | B2 | D | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.2 | 12.7 | 35 | 66.5 | 4 × 15.7 | 1/2" | 38.1 | 20.6 | 22.4 | 9.7 | 15.7 | 0.67 |
| NPS 3/4 | 117.3 | 14.2 | 42.9 | 82.5 | 4 × 19 | 5/8" | 47.8 | 23.9 | 27.7 | 11.2 | 20.8 | 1.1 |
| NPS 1 | 123.9 | 15.7 | 50.8 | 88.9 | 4 × 19 | 5/8" | 53.8 | 25.4 | 34.5 | 12.7 | 26.7 | 1.4 |
| NPS 1 1/4 | 133.3 | 17.5 | 63.5 | 98.5 | 4 × 19 | 5/8" | 63.5 | 25.4 | 43.2 | 14.2 | 35.1 | 1.7 |
| NPS 1 1/2 | 155.4 | 19.1 | 73.1 | 114.3 | 4 × 22.3 | 3/4" | 69.9 | 28.7 | 49.5 | 15.7 | 40.9 | 2.6 |
| NPS 2 | 165.1 | 20.6 | 91.9 | 127 | 8 × 19 | 5/8" | 84.1 | 31.8 | 62.0 | 17.5 | 52.6 | 3 |
| NPS 2 1/2 | 190.5 | 23.9 | 104.6 | 149.3 | 8 × 22.3 | 3/4" | 100.1 | 36.6 | 74.7 | 19.1 | 62.7 | 4.5 |
| NPS 3 | 209.5 | 26.9 | 127 | 168.1 | 8 × 22.3 | 3/4" | 117.3 | 41.4 | 90.7 | 20.6 | 78.0 | 6.1 |
| NPS | O | tf | R | W | Z × ØI | Stud | X | Y | B2 | D | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.3 | 14.2 | 35.1 | 66.5 | 4 × 16.0 | 0.505" | 38.1 | 22.4 | 22.4 | 9.7 | – | 0.77 |
| NPS 3/4 | 117.3 | 15.7 | 42.9 | 82.6 | 4 × 19.1 | 0.625" | 47.8 | 25.4 | 27.7 | 11.2 | – | 1.3 |
| NPS 1 | 124.0 | 17.5 | 50.8 | 88.9 | 4 × 19.1 | 0.625" | 53.8 | 26.9 | 34.5 | 12.7 | – | 1.6 |
| NPS 1 1/4 | 133.4 | 20.6 | 63.5 | 98.6 | 4 × 19.1 | 0.625" | 63.5 | 28.4 | 43.2 | 14.2 | – | 2.1 |
| NPS 1 1/2 | 155.4 | 22.4 | 73.2 | 114.3 | 4 × 22.4 | 0.755" | 69.9 | 31.8 | 49.5 | 15.7 | – | 3.1 |
| NPS 2 | 165.1 | 25.4 | 91.9 | 127.0 | 8 × 19.1 | 0.625" | 84.1 | 36.6 | 62.0 | 17.5 | – | 3.8 |
| NPS 2 1/2 | 190.5 | 28.4 | 104.6 | 149.4 | 8 × 22.4 | 0.755" | 100.1 | 41.1 | 74.7 | 19.1 | – | 5.5 |
| NPS 3 | 209.6 | 31.8 | 127.0 | 168.1 | 8 × 22.4 | 0.755" | 117.3 | 46.0 | 90.7 | 20.6 | – | 7.4 |
| NPS | O | tf | R | W | Z × ØI | Stud | X | Y | B2 | D | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 95.3 | 14.2 | 35.1 | 66.5 | 4 × 15.7 | 1/2" | 38.1 | 22.4 | 22.4 | 9.7 | 14.0 | 0.78 |
| NPS 3/4 | 117.3 | 15.7 | 42.9 | 82.6 | 4 × 19.1 | 5/8" | 47.8 | 25.4 | 27.7 | 11.2 | 18.8 | 1.3 |
| NPS 1 | 124 | 17.5 | 50.8 | 88.9 | 4 × 19.1 | 5/8" | 53.8 | 26.9 | 34.5 | 12.7 | 24.4 | 1.6 |
| NPS 1 1/4 | 133.4 | 20.6 | 63.5 | 98.6 | 4 × 19.1 | 5/8" | 63.5 | 28.4 | 43.2 | 14.2 | 32.5 | 2.1 |
| NPS 1 1/2 | 155.4 | 22.4 | 73.2 | 114.3 | 4 × 22.4 | 3/4" | 69.9 | 31.8 | 49.5 | 15.7 | 38.1 | 3.1 |
| NPS 2 | 165.1 | 25.4 | 91.9 | 127 | 8 × 19.1 | 5/8" | 84.1 | 36.6 | 62.0 | 17.5 | 49.3 | 3.8 |
| NPS 2 1/2 | 190.5 | 28.4 | 104.6 | 149.4 | 8 × 22.4 | 3/4" | 100.1 | 41.1 | 74.7 | 19.1 | 58.9 | 5.6 |
| NPS 3 | 209.6 | 31.8 | 127 | 168.1 | 8 × 22.4 | 3/4" | 117.3 | 46.0 | 90.7 | 20.6 | 73.7 | 7.6 |
| NPS | O | tf | R | W | Z × ØI | Stud | X | Y | B2 | D | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 120.6 | 22.4 | 35.1 | 82.5 | 4 × 22.4 | 3/4" | 38.1 | 31.8 | 22.4 | 9.7 | – | 1.8 |
| NPS 3/4 | 130 | 25.4 | 42.9 | 88.9 | 4 × 22.4 | 3/4" | 44.5 | 35.1 | 27.7 | 11.2 | – | 2.4 |
| NPS 1 | 149.4 | 28.4 | 50.8 | 101.6 | 4 × 25.4 | 7/8" | 52.3 | 41.1 | 34.5 | 12.7 | – | 3.5 |
| NPS 1 1/4 | 158.8 | 28.4 | 63.5 | 111.3 | 4 × 25.4 | 7/8" | 63.5 | 41.1 | 43.2 | 14.2 | – | 4 |
| NPS 1 1/2 | 177.8 | 31.8 | 73.2 | 124 | 4 × 28.4 | 1" | 69.9 | 44.5 | 49.5 | 15.7 | – | 5.6 |
| NPS 2 | 215.9 | 38.1 | 91.9 | 165.1 | 8 × 25.4 | 7/8" | 104.6 | 57.2 | 62.0 | 17.5 | – | 10.2 |
| NPS 2 1/2 | 244.3 | 41.1 | 104.6 | 190.5 | 8 × 28.4 | 1" | 124.0 | 63.5 | 74.7 | 19.1 | – | 14.2 |
| NPS 3 | 241.3 | 38.1 | 127 | 190.5 | 8 × 25.4 | 7/8" | 127.0 | 53.8 | 90.7 | – | – | – |
| NPS | O | tf | R | W | Z × ØI | Stud | X | Y | B2 | D | B | G (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPS 1/2 | 120.6 | 22.4 | 35.1 | 82.5 | 4 × 22.4 | 3/4" | 38.1 | 31.8 | 22.4 | 9.7 | – | 1.8 |
| NPS 3/4 | 130 | 25.4 | 42.9 | 88.9 | 4 × 22.4 | 3/4" | 44.5 | 35.1 | 27.7 | 11.2 | – | 2.4 |
| NPS 1 | 149.4 | 28.4 | 50.8 | 101.6 | 4 × 25.4 | 7/8" | 52.3 | 41.1 | 34.5 | 12.7 | – | 3.6 |
| NPS 1 1/4 | 158.8 | 28.4 | 63.5 | 111.3 | 4 × 25.4 | 7/8" | 63.5 | 41.1 | 43.2 | 14.2 | – | 4.1 |
| NPS 1 1/2 | 177.8 | 31.8 | 73.2 | 124 | 4 × 28.4 | 1" | 69.9 | 44.5 | 49.5 | 15.7 | – | 5.6 |
| NPS 2 | 215.9 | 38.1 | 91.9 | 165.1 | 8 × 25.4 | 7/8" | 104.6 | 57.2 | 62.0 | 17.5 | – | 10.3 |
| NPS 2 1/2 | 244.3 | 41.1 | 104.6 | 190.5 | 8 × 28.4 | 1" | 124.0 | 63.5 | 74.7 | 19.1 | – | 14.3 |
| NPS 3 | 266.7 | 47.8 | 127 | 203.2 | 8 × 31.8 | 1 1/8" | 133.4 | – | – | – | – | – |
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, pipe schedule, material, certificate – for example “socket weld flange NPS 1 Class 300 SW RF, SCH 80, ASTM A105, EN 10204 3.1”. The schedule determines the through bore B. If you weld in a metric pipe, give its outside diameter – the socket is sized for inch pipe to ASME B36.10M.
Further in the topic
In the topic: ASME connecting dimensions · Weld neck flange ASME B16.5 · Slip-on flange ASME B16.5 · Blind 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 socket weld flange NPS 1 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.
Why are socket weld flanges only made up to NPS 3?
The standard covers this type only from NPS 1/2 to 3. Above that, slip-on or weld neck flanges are used – a fillet weld on a socket becomes uneconomic at large sizes.
What is the gap at the socket shoulder for?
The pipe is withdrawn about 1.5 mm before welding. The fillet weld contracts as it cools – if the pipe bottoms on the shoulder, the weld can crack. The gap is part of the assembly, not of the flange.
Socket weld flange or slip-on flange?
Both are slid over the pipe. The socket weld flange has a socket with a shoulder and is welded outside only, the slip-on flange has a straight bore and is welded inside and outside. Which type is permitted is set by the code that applies to the plant.
Enquire about socket weld flanges ASME B16.5
Give NPS, class, schedule, facing, material and certificate – or simply what you have. We will clarify the rest with you.
Send an inquiryYour inquiry to Zickwolff
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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.