ASME B16.5 Class 2500 Flange Dimensions
This chart gives the dimensions of ASME B16.5 Class 2500 pipe flanges in millimetres for NPS ½" to 12". It covers weld neck, slip-on, blind, socket weld, threaded and lap joint flanges, with drilling, stud bolt lengths and approximate weights.
For carbon steel flanges in ASTM A105 (material group 1.1) the Class 2500 working pressure is 425.5 bar at −29 to 38 °C, falling as temperature rises — see the pressure–temperature ratings. Teshi Group manufactures these flanges as an OEM in carbon, stainless and alloy steel.
Key to dimensions
- O
- Outside diameter of flange
- tf
- Minimum flange thickness (also the blind flange thickness), excluding the raised face
- R
- Diameter of raised face
- X
- Hub diameter at base
- A
- Hub diameter at the welding end of a weld neck flange (pipe outside diameter)
- Y
- Length through hub — given separately for weld neck, slip-on / threaded / socket weld and lap joint flanges
- W
- Bolt circle diameter
- Holes
- Number and diameter of bolt holes
- Bolt
- Nominal bolt diameter in inches
ASME B16.5 Class 2500 flange types — drawings
The table covers every flange type of this class. Each drawing shows which dimensions apply; open a type for its own chart.
ASME B16.5 Class 2500 Flange dimensions — tables
Class 2500 flange dimensions (mm)
| NPSin | DN | OOutside dia | tfMin thickness | RRaised face dia | XHub dia | AHub at weld | YWeld neck | YSlip-on / Thr / SW | YLap joint | WBolt circle | HolesNo. | Hole diamm | Boltin |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ½" | 15 | 135 | 30.2 | 34.9 | 43 | 21.3 | 73 | 40 | 40 | 88.9 | 4 | 22.2 | ¾" |
| ¾" | 20 | 140 | 31.8 | 42.9 | 51 | 26.7 | 79 | 43 | 43 | 95.2 | 4 | 22.2 | ¾" |
| 1" | 25 | 160 | 35.0 | 50.8 | 57 | 33.4 | 89 | 48 | 48 | 108.0 | 4 | 25.4 | ⅞" |
| 1¼" | 32 | 185 | 38.1 | 63.5 | 73 | 42.2 | 95 | 52 | 52 | 130.2 | 4 | 28.6 | 1" |
| 1½" | 40 | 205 | 44.5 | 73.0 | 79 | 48.3 | 111 | 60 | 60 | 146.0 | 4 | 31.8 | 1⅛" |
| 2" | 50 | 235 | 50.9 | 92.1 | 95 | 60.3 | 127 | 70 | 70 | 171.4 | 8 | 28.6 | 1" |
| 2½" | 65 | 265 | 57.2 | 104.8 | 114 | 73.0 | 143 | 79 | 79 | 196.8 | 8 | 31.8 | 1⅛" |
| 3" | 80 | 305 | 66.7 | 127.0 | 133 | 88.9 | 168 | 92 | 92 | 228.6 | 8 | 34.9 | 1¼" |
| 4" | 100 | 355 | 76.2 | 157.2 | 165 | 114.3 | 190 | 108 | 108 | 273.0 | 8 | 41.3 | 1½" |
| 5" | 125 | 420 | 92.1 | 185.7 | 203 | 141.3 | 229 | 130 | 130 | 323.8 | 8 | 47.6 | 1¾" |
| 6" | 150 | 485 | 108.0 | 215.9 | 235 | 168.3 | 273 | 152 | 152 | 368.3 | 8 | 54.0 | 2" |
| 8" | 200 | 550 | 127.0 | 269.9 | 305 | 219.1 | 318 | 178 | 178 | 438.2 | 12 | 54.0 | 2" |
| 10" | 250 | 675 | 165.1 | 323.8 | 375 | 273.0 | 419 | 229 | 229 | 539.8 | 12 | 66.7 | 2½" |
| 12" | 300 | 760 | 184.2 | 381.0 | 441 | 323.8 | 464 | 254 | 254 | 619.1 | 12 | 73.0 | 2¾" |
Class 2500 bolting and approximate weights
| NPSin | StudsNo. | Stud diain | Stud lengthRaised face | Stud lengthRing joint | Weld neckkg, approx. | Blindkg, approx. |
|---|---|---|---|---|---|---|
| ½" | 4 | ¾" | 120 | 120 | 3.6 | 3.2 |
| ¾" | 4 | ¾" | 125 | 125 | 4.1 | — |
| 1" | 4 | ⅞" | 140 | 140 | 5.9 | 5.0 |
| 1¼" | 4 | 1" | 150 | 150 | 9.1 | 7.8 |
| 1½" | 4 | 1⅛" | 170 | 170 | 12.7 | 10.5 |
| 2" | 8 | 1" | 180 | 180 | 19.1 | 18 |
| 2½" | 8 | 1⅛" | 195 | 205 | 23.6 | 25.5 |
| 3" | 8 | 1¼" | 220 | 230 | 42.6 | 39 |
| 4" | 8 | 1½" | 255 | 260 | 66.2 | 61.5 |
| 5" | 8 | 1¾" | 300 | 310 | 111 | 102 |
| 6" | 8 | 2" | 345 | 355 | 171 | 157 |
| 8" | 12 | 2" | 380 | 395 | 261 | 241 |
| 10" | 12 | 2½" | 490 | 510 | 484 | 470 |
| 12" | 12 | 2¾" | 540 | 560 | 729 | — |
Notes
- Dimensions are in millimetres unless stated otherwise.
- Flange thickness tf and length through hub Y do not include the 7 mm raised face.
- Blind flanges have the same outside diameter, thickness tf and drilling as the other flange types of the same size and class.
- ASME B16.5 has no Class 2500 slip-on or socket weld flange; the slip-on column applies to threaded flanges only.
- The bore of a weld neck or socket weld flange is machined to match the inside diameter of the pipe schedule stated in the order.
- Bolt holes are tabulated in inches in ASME B16.5; the millimetre values shown are direct conversions (bolt diameter plus ⅛").
- Stud bolt lengths do not include the height of the points. Weights are approximate catalogue values and vary with bore and manufacturer.
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
Equivalent and related standards to ASME B16.5 Class 2500 Flange Dimensions
All equivalents| Region | Standard | Relationship |
|---|---|---|
| Europe | EN 1759-1 Class 2500 | Class-rated steel flanges based on ASME B16.5 dimensions (metric bolting) |
| China | HG/T 20615 Class 2500 (PN 420) | Chemical-industry Class flanges — ASME B16.5 dimensions |
| China | GB/T 9124.2 Class 2500 | National standard steel pipe flanges, Class series — ASME B16.5 dimensions |
| China | SH/T 3406 Class 2500 | Petrochemical steel pipe flanges — ASME B16.5 dimensions |
| UK | BS 1560 Class 2500 (withdrawn) | Former British adoption of ASME B16.5 |
| International | ISO 7005-1 Class 2500 series | ISO steel flanges, Class designations aligned with ASME B16.5 |
| USA | ASME B16.47 Series A / MSS SP-44 | Same classes for NPS 26 and larger |
| Japan | JIS B2220 (K ratings) | Not interchangeable — JIS uses its own 5K–30K pressure ratings and dimensions |
Teshi Group manufactures flanges and fittings to all of these standards on request, including Chinese GB / HG / SH and European EN dimensions for export projects. Always confirm bolting, facing and thickness when substituting one standard for another.
Dimension finder
Pick a product, standard and size — or just type — to see every dimension and download a watermarked PDF for that one size.
ASME B16.5 Class 2500 Flange Dimensions — size by size
Every size has its own page with a drawing, mm and inch values and a one-size PDF.
FAQ
ASME B16.5 Class 2500 flange dimensions: common questions
What is the pressure rating of a Class 2500 flange?
For ASTM A105 carbon steel (ASME B16.5 material group 1.1) a Class 2500 flange is rated 425.5 bar at −29 to 38 °C. The rating depends on material group and decreases with temperature.
What are the dimensions of a 4 inch Class 2500 flange?
A NPS 4" Class 2500 flange has an outside diameter of 355 mm, a minimum thickness of 76.2 mm, a bolt circle of 273.0 mm and 8 bolt holes for 1½" bolts.
Does the flange thickness include the raised face?
No. For Class 2500 the 7 mm raised face is additional to the minimum flange thickness tf shown in the chart.
Related products, data sheets and standards
Weld Neck Flange
OEM manufacturer
View online · PDFTechnical data sheetSlip-On Flange
OEM manufacturer
View online · PDFTechnical data sheetBlind Flange
OEM manufacturer
View online · PDFTechnical data sheetSocket Weld Flange
OEM manufacturer
View online · PDFTechnical data sheetThreaded Flange
OEM manufacturer
View online · PDFTechnical data sheetLap Joint Flange
OEM manufacturer
View online · PDFASME B16.5ASME B16.5 Class 150 flange dimensions
Class 150 weld neck, slip-on, blind, socket weld, threaded and lap joint flange dimensions, NPS ½–24, in mm.
View online · PDFASME B16.5ASME B16.5 Class 300 flange dimensions
Class 300 flange outside diameter, thickness, hub and drilling dimensions, NPS ½–24, in mm.
View online · PDFASME B16.5ASME B16.5 Class 600 flange dimensions
Class 600 flange dimensions and bolting, NPS ½–24, in mm.
View online · PDFASME B16.5ASME B16.5 Class 900 flange dimensions
Class 900 flange dimensions and bolting, NPS ½–24, in mm.
View online · PDFASME B16.5ASME B16.5 Class 1500 flange dimensions
Class 1500 flange dimensions and bolting, NPS ½–24, in mm.
View online · PDFASME B16.5Stud bolt chart for ASME B16.5 flanges
Number, diameter and length of stud bolts for raised-face and ring-joint flanges, Class 150–2500.
View online · PDFASME B16.5ASME B16.5 pressure–temperature ratings
Flange working pressure by class and temperature for carbon, alloy and stainless steel material groups, in bar.
View online · PDFOEM manufacturerIndustrial Flanges
NPS ½"–60" · CS / SS / Alloy
OpenOEM manufacturerFasteners
M10–M64 · ½"–4" · Alloy / SS
OpenStockist & supplierGaskets & Seals
NPS ½"–60" · Metallic / Soft
Open
Ready to build to spec?
Share your drawing, bill of materials or technical requirements with the Teshi team.