ASME B16.5 Class 900 Flange Dimensions
This chart gives the dimensions of ASME B16.5 Class 900 pipe flanges in millimetres for NPS ½" to 24". 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 900 working pressure is 153.2 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 900 Flange dimensions — tables
Class 900 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 | 120 | 22.3 | 34.9 | 38 | 21.3 | 60 | 32 | 32 | 82.6 | 4 | 22.2 | ¾" |
| ¾" | 20 | 130 | 25.4 | 42.9 | 44 | 26.7 | 70 | 35 | 35 | 88.9 | 4 | 22.2 | ¾" |
| 1" | 25 | 150 | 28.6 | 50.8 | 52 | 33.4 | 73 | 41 | 41 | 101.6 | 4 | 25.4 | ⅞" |
| 1¼" | 32 | 160 | 28.6 | 63.5 | 64 | 42.2 | 73 | 41 | 41 | 111.1 | 4 | 25.4 | ⅞" |
| 1½" | 40 | 180 | 31.8 | 73.0 | 70 | 48.3 | 83 | 44 | 44 | 123.8 | 4 | 28.6 | 1" |
| 2" | 50 | 215 | 38.1 | 92.1 | 105 | 60.3 | 102 | 57 | 57 | 165.1 | 8 | 25.4 | ⅞" |
| 2½" | 65 | 245 | 41.3 | 104.8 | 124 | 73.0 | 105 | 64 | 64 | 190.5 | 8 | 28.6 | 1" |
| 3" | 80 | 240 | 38.1 | 127.0 | 127 | 88.9 | 102 | 54 | 54 | 190.5 | 8 | 25.4 | ⅞" |
| 4" | 100 | 290 | 44.5 | 157.2 | 159 | 114.3 | 114 | 70 | 70 | 235.0 | 8 | 31.8 | 1⅛" |
| 5" | 125 | 350 | 50.8 | 185.7 | 190 | 141.3 | 127 | 79 | 79 | 279.4 | 8 | 34.9 | 1¼" |
| 6" | 150 | 380 | 55.6 | 215.9 | 235 | 168.3 | 140 | 86 | 86 | 317.5 | 12 | 31.8 | 1⅛" |
| 8" | 200 | 470 | 63.5 | 269.9 | 298 | 219.1 | 162 | 102 | 114 | 393.7 | 12 | 38.1 | 1⅜" |
| 10" | 250 | 545 | 69.9 | 323.8 | 368 | 273.0 | 184 | 108 | 127 | 469.9 | 16 | 38.1 | 1⅜" |
| 12" | 300 | 610 | 79.4 | 381.0 | 419 | 323.8 | 200 | 117 | 143 | 533.4 | 20 | 38.1 | 1⅜" |
| 14" | 350 | 640 | 85.8 | 412.8 | 451 | 355.6 | 213 | 130 | 156 | 558.8 | 20 | 41.3 | 1½" |
| 16" | 400 | 705 | 88.9 | 469.9 | 508 | 406.4 | 216 | 133 | 165 | 616.0 | 20 | 44.5 | 1⅝" |
| 18" | 450 | 785 | 101.6 | 533.4 | 565 | 457.0 | 229 | 152 | 190 | 685.8 | 20 | 50.8 | 1⅞" |
| 20" | 500 | 855 | 108.0 | 584.2 | 622 | 508.0 | 248 | 159 | 210 | 749.3 | 20 | 54.0 | 2" |
| 24" | 600 | 1040 | 139.7 | 692.2 | 749 | 610.0 | 292 | 203 | 267 | 901.7 | 20 | 66.7 | 2½" |
Class 900 bolting and approximate weights
| NPSin | StudsNo. | Stud diain | Stud lengthRaised face | Stud lengthRing joint | Weld neckkg, approx. | Slip-onkg, approx. | Blindkg, approx. |
|---|---|---|---|---|---|---|---|
| ½" | 4 | ¾" | 110 | 110 | — | 1.8 | 1.8 |
| ¾" | 4 | ¾" | 115 | 115 | — | 2.3 | 2.7 |
| 1" | 4 | ⅞" | 125 | 125 | 4.1 | 3.4 | 3.7 |
| 1¼" | 4 | ⅞" | 125 | 125 | 4.5 | 4.3 | 4.1 |
| 1½" | 4 | 1" | 140 | 140 | 6.4 | 5.5 | 5.9 |
| 2" | 8 | ⅞" | 145 | 145 | 11.3 | 10.0 | 10.1 |
| 2½" | 8 | 1" | 160 | 160 | 16.3 | 16.3 | 15.9 |
| 3" | 8 | ⅞" | 145 | 145 | 13.6 | — | 13.2 |
| 4" | 8 | 1⅛" | 170 | 170 | 24.0 | 24.0 | 24.0 |
| 5" | 8 | 1¼" | 190 | 190 | 39.0 | 38.0 | 39.0 |
| 6" | 12 | 1⅛" | 190 | 195 | 50.0 | 50.0 | 52.0 |
| 8" | 12 | 1⅜" | 220 | 220 | 84.0 | 78.0 | 90.0 |
| 10" | 16 | 1⅜" | 235 | 235 | 121 | 111 | 132 |
| 12" | 20 | 1⅜" | 255 | 255 | — | 148 | 188 |
| 14" | 20 | 1½" | 275 | 280 | — | 181 | 235 |
| 16" | 20 | 1⅝" | 285 | 290 | — | 200 | 276 |
| 18" | 20 | 1⅞" | 325 | 335 | — | 282 | 391 |
| 20" | 20 | 2" | 350 | 360 | — | 344 | 493 |
| 24" | 20 | 2½" | 440 | 455 | — | 651 | 932 |
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.
- In ASME B16.5, Class 900 flanges NPS ½" to 2½" use Class 1500 dimensions.
- 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.
FAQ
ASME B16.5 Class 900 flange dimensions: common questions
What is the pressure rating of a Class 900 flange?
For ASTM A105 carbon steel (ASME B16.5 material group 1.1) a Class 900 flange is rated 153.2 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 900 flange?
A NPS 4" Class 900 flange has an outside diameter of 290 mm, a minimum thickness of 44.5 mm, a bolt circle of 235.0 mm and 8 bolt holes for 1⅛" bolts.
Does the flange thickness include the raised face?
No. For Class 900 the 7 mm raised face is additional to the minimum flange thickness tf shown in the chart.
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