ASME B16.5 · ASTM A105 · stock and made to order
2½″ Class 150 Weld Neck Flange — ASME B16.5
2½″ Class 150 weld neck flange to ASME B16.5, machined from ASTM A105. Outside diameter 177.8 mm, thickness 20.6 mm, 4 bolt holes on a 139.7 mm circle, approximate weight 3.6 kg. Available with raised face, flat face or the facing specified on your drawing.
Size
2½″ / DN65
Standard
ASME B16.5 (ASME B16.5-2025)
Pressure rating
Class 150
Outside diameter
177.8 mm (7″)
Thickness
20.6 mm (0.81″)
Bolt circle
139.7 mm (5.5″)
Approx. weight
3.6 kg
Full dimensions — 2½″ Class 150
| Size | DN | OD | Thickness | RF Ø | Bolt circle | Bolts | Hub Ø | Length | Weight | |
|---|---|---|---|---|---|---|---|---|---|---|
| 1/2″ | 15 | 88.9 mm (3.5″) | 9.7 mm (0.38″) | 35.1 mm (1.38″) | 60.5 mm (2.38″) | 4 × Ø15.9 mm (0.63″) | 30.2 mm (1.19″) | 46 mm (1.81″) | 0.9 kg | Details → |
| 3/4″ | 20 | 98.6 mm (3.88″) | 11.2 mm (0.44″) | 42.9 mm (1.69″) | 69.9 mm (2.75″) | 4 × Ø15.9 mm (0.63″) | 38.1 mm (1.5″) | 50.8 mm (2″) | 0.9 kg | Details → |
| 1″ | 25 | 108 mm (4.25″) | 12.7 mm (0.5″) | 50.8 mm (2″) | 79.2 mm (3.12″) | 4 × Ø15.9 mm (0.63″) | 49.3 mm (1.94″) | 53.8 mm (2.12″) | 1.4 kg | Details → |
| 1¼″ | 32 | 117.3 mm (4.62″) | 14.2 mm (0.56″) | 63.5 mm (2.5″) | 88.9 mm (3.5″) | 4 × Ø15.9 mm (0.63″) | 58.7 mm (2.31″) | 55.6 mm (2.19″) | 1.4 kg | Details → |
| 1½″ | 40 | 127 mm (5″) | 15.7 mm (0.62″) | 73.2 mm (2.88″) | 98.6 mm (3.88″) | 4 × Ø15.9 mm (0.63″) | 65 mm (2.56″) | 60.5 mm (2.38″) | 1.8 kg | Details → |
| 2″ | 50 | 152.4 mm (6″) | 17.5 mm (0.69″) | 91.9 mm (3.62″) | 120.7 mm (4.75″) | 4 × Ø19.1 mm (0.75″) | 77.7 mm (3.06″) | 62 mm (2.44″) | 2.7 kg | Details → |
| 2½″ (this size) | 65 | 177.8 mm (7″) | 20.6 mm (0.81″) | 104.6 mm (4.12″) | 139.7 mm (5.5″) | 4 × Ø19.1 mm (0.75″) | 90.4 mm (3.56″) | 68.3 mm (2.69″) | 3.6 kg | Details → |
| 3″ | 80 | 190.5 mm (7.5″) | 22.4 mm (0.88″) | 127 mm (5″) | 152.4 mm (6″) | 4 × Ø19.1 mm (0.75″) | 108 mm (4.25″) | 68.3 mm (2.69″) | 4.5 kg | Details → |
| 3½″ | 90 | 215.9 mm (8.5″) | 22.4 mm (0.88″) | 139.7 mm (5.5″) | 177.8 mm (7″) | 8 × Ø19.1 mm (0.75″) | 122.2 mm (4.81″) | 69.9 mm (2.75″) | 5.4 kg | Details → |
| 4″ | 100 | 228.6 mm (9″) | 22.4 mm (0.88″) | 157.2 mm (6.19″) | 190.5 mm (7.5″) | 8 × Ø19.1 mm (0.75″) | 134.9 mm (5.31″) | 74.7 mm (2.94″) | 6.8 kg | Details → |
| 5″ | 125 | 254 mm (10″) | 22.4 mm (0.88″) | 185.7 mm (7.31″) | 215.9 mm (8.5″) | 8 × Ø22.2 mm (0.87″) | 163.6 mm (6.44″) | 87.4 mm (3.44″) | 8.6 kg | Details → |
| 6″ | 150 | 279.4 mm (11″) | 23.9 mm (0.94″) | 215.9 mm (8.5″) | 241.3 mm (9.5″) | 8 × Ø22.2 mm (0.87″) | 192 mm (7.56″) | 87.4 mm (3.44″) | 10.9 kg | Details → |
| 8″ | 200 | 342.9 mm (13.5″) | 26.9 mm (1.06″) | 269.7 mm (10.62″) | 298.5 mm (11.75″) | 8 × Ø22.2 mm (0.87″) | 246.1 mm (9.69″) | 100.1 mm (3.94″) | 17.7 kg | Details → |
| 10″ | 250 | 406.4 mm (16″) | 28.4 mm (1.12″) | 323.9 mm (12.75″) | 362 mm (14.25″) | 12 × Ø25.4 mm (1″) | 304.8 mm (12″) | 100.1 mm (3.94″) | 23.6 kg | Details → |
| 12″ | 300 | 482.6 mm (19″) | 30.2 mm (1.19″) | 381 mm (15″) | 431.8 mm (17″) | 12 × Ø25.4 mm (1″) | 365.3 mm (14.38″) | 112.8 mm (4.44″) | 36.3 kg | Details → |
| 14″ | 350 | 533.4 mm (21″) | 33.3 mm (1.31″) | 412.8 mm (16.25″) | 476.3 mm (18.75″) | 12 × Ø28.6 mm (1.13″) | 400.1 mm (15.75″) | 125.5 mm (4.94″) | 49.9 kg | Details → |
| 16″ | 400 | 596.9 mm (23.5″) | 35.1 mm (1.38″) | 469.9 mm (18.5″) | 539.8 mm (21.25″) | 16 × Ø28.6 mm (1.13″) | 457.2 mm (18″) | 125.5 mm (4.94″) | 63.5 kg | Details → |
| 18″ | 450 | 635 mm (25″) | 38.1 mm (1.5″) | 533.4 mm (21″) | 577.9 mm (22.75″) | 16 × Ø31.8 mm (1.25″) | 505 mm (19.88″) | 138.2 mm (5.44″) | 68 kg | Details → |
| 20″ | 500 | 698.5 mm (27.5″) | 41.1 mm (1.62″) | 584.2 mm (23″) | 635 mm (25″) | 20 × Ø31.8 mm (1.25″) | 558.8 mm (22″) | 142.7 mm (5.62″) | 81.6 kg | Details → |
| 22″ | 550 | 749.3 mm (29.5″) | 44.5 mm (1.75″) | 641.4 mm (25.25″) | 692.2 mm (27.25″) | 20 × Ø28.6 mm (1.13″) | 609.6 mm (24″) | 147.8 mm (5.82″) | — | Details → |
| 24″ | 600 | 812.8 mm (32″) | 46 mm (1.81″) | 692.2 mm (27.25″) | 749.3 mm (29.5″) | 20 × Ø34.9 mm (1.37″) | 663.4 mm (26.12″) | 150.9 mm (5.94″) | 118 kg | Details → |
Published ASME B16.5 dimensions for every Class 150 size in this product family.
Dimensions in millimetres; the inch equivalent is shown in brackets. Bolt hole diameter applies to through-holes. For stud length, gasket and bolting selection, match the gasket and bolts to B16.5.
What Class 150 means in service
Class 150 in ASTM A105 (material group 1.1) is rated 285 psi (19.6 bar) at 38 °C (100 °F) in the ASME B16.5-2025 tables, and derates as temperature rises. Read the value for your design temperature and material group from the 2025 pressure–temperature table.
ASME classes are not fixed pressures. For ASTM A105 (material group 1.1) the ASME B16.5-2025 ambient rating is 285 psi (19.6 bar) at Class 150, 740 psi (51.0 bar) at Class 300, 985 psi (68.0 bar) at Class 400, 1,480 psi (102.0 bar) at Class 600, 2,220 psi (153.1 bar) at Class 900, 3,705 psi (255.1 bar) at Class 1500 and 6,170 psi (425.1 bar) at Class 2500 at 38 °C (100 °F), derating as temperature rises. The 2025 edition revised the rating tables (record 23-2509); these are the 2025 values and the full temperature tables are on the ASME B16.5 pressure-ratings page.
Facing and materials
Raised face (RF) is standard: 1.5 mm high for Classes 150 and 300, 6.4 mm for Classes 400 to 2500, added to the minimum flange thickness. Flat face (FF) and ring-type joint (RTJ) faces are available on request.
- ASTM A105 / A105N
- ASTM A350 LF2
- ASTM A182 F304/F316L
- ASTM A182 F11/F22/F91
- ASTM A182 F51/F53
Other grades, impact-tested heats and NACE MR0175 requirements are quoted on request. Material certificates to EN 10204 3.1 are issued against the same heat number as the dimensional report.
Inspection and delivery
- Dimensional inspection against the B16.5 table for 2½″ Class 150
- Heat number stamped on the rim; EN 10204 3.1 certificate issued
- PMI on stainless and alloy heats; UT/RT on request
- Anti-rust oil, plywood case or pallet, with packing list and MTC
- Typical lead time 7–15 days for carbon steel stock sizes, 20–30 days for alloys
Other sizes in Class 150
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2½″ Class 150 Weld Neck Flange
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