Kalp Alloys is a leading manufacturer and supplier of Class 600 Flanges (also known as 600 lb flanges or 600# flanges) conforming to ASME B16.5 standard. We supply Class 600 pipe flanges in all standard types — Slip-On (SOF), Welding Neck (WNF), Socket Welding (SWF), Threaded (THDF), Lap Joint (LJF), and Blind (BLF) — in sizes ranging from NPS 1/2″ to NPS 24″. Our flanges are manufactured in a wide range of materials including Stainless Steel (SS 304, 316L, 321), Carbon Steel, Alloy Steel, Duplex, and Nickel Alloys to meet the most demanding industrial requirements.
A Class 600 flange is a pressure-class designation under the ASME B16.5 standard (Steel Pipe Flanges and Flanged Fittings). The “600” refers to the pressure class — designed for high-pressure and high-temperature industrial piping systems. Class 600 flanges are rated at approximately 1480 psi (102 bar) at ambient temperature (38°C) for carbon steel.
They are widely used in oil & gas, refineries, petrochemical plants, power generation, and critical high-pressure piping systems where elevated pressures and temperatures are encountered. Because of their robust construction and high-pressure capability, ASME B16.5 Class 600 flanges are the preferred choice for demanding industrial applications requiring twice the pressure rating of Class 600.
| NPS | Outside Diam. D | Diam. of Hub X | OD of RF G | Thickness (Min) t | Bore | Length thru Hub | Diam. of Hub at Bevel A | Drilling | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| WNF SWF B1 | SOF SWF (Min) | LJF (Min) | THDF Counter bore (Min) | WNF T1 | SOF THDF SWF | LJF T3 | BCD C | Number of Bolt Holes N | Diam. of Bolt Holes (*) H | ||||||
| B2 | B3 | B | T2 | ||||||||||||
| 1/2 | 95 | 38 | 34.9 | 14.3 | See Note (1) To be specified by Purchaser | 22.2 | 22.9 | 23.6 | 52 | 22 | 22 | 21.3 | 66.7 | 4 | 15.9 |
| 3/4 | 115 | 48 | 42.9 | 15.9 | 27.7 | 28.2 | 29.0 | 57 | 25 | 25 | 26.7 | 82.6 | 4 | 19.1 | |
| 1 | 125 | 54 | 50.8 | 17.5 | 34.5 | 34.9 | 35.8 | 62 | 27 | 27 | 33.4 | 88.9 | 4 | 19.1 | |
| 1 1/4 | 135 | 64 | 63.5 | 20.7 | 43.2 | 43.7 | 44.4 | 67 | 29 | 29 | 42.2 | 98.4 | 4 | 19.1 | |
| 1 1/2 | 155 | 70 | 73.0 | 22.3 | 49.5 | 50.0 | 50.6 | 70 | 32 | 32 | 48.3 | 114.3 | 4 | 22.2 | |
| 2 | 165 | 84 | 92.1 | 25.4 | 61.9 | 62.5 | 63.5 | 73 | 37 | 37 | 60.3 | 127.0 | 8 | 19.1 | |
| 2 1/2 | 190 | 100 | 104.8 | 28.6 | 74.6 | 75.4 | 76.2 | 79 | 41 | 41 | 73.0 | 149.2 | 8 | 22.2 | |
| 3 | 210 | 117 | 127.0 | 31.8 | 90.7 | 91.4 | 92.2 | 83 | 46 | 46 | 88.9 | 168.3 | 8 | 22.2 | |
| 3 1/2 | 230 | 133 | 139.7 | 35.0 | 103.4 | 104.1 | 104.9 | 86 | 49 | 49 | 101.6 | 184.2 | 8 | 25.4 | |
| 4 | 275 | 152 | 157.2 | 38.1 | 116.1 | 116.8 | 117.6 | 102 | 54 | 54 | 114.3 | 215.9 | 8 | 25.4 | |
| 5 | 330 | 189 | 185.7 | 44.5 | 143.8 | 144.4 | 144.4 | 114 | 60 | 60 | 141.3 | 266.7 | 8 | 28.6 | |
| 6 | 355 | 222 | 215.9 | 47.7 | 170.7 | 171.4 | 171.4 | 117 | 67 | 67 | 168.3 | 292.1 | 12 | 28.6 | |
| 8 | 420 | 273 | 269.9 | 55.6 | 221.5 | 222.2 | 222.2 | 133 | 76 | 76 | 219.1 | 349.2 | 12 | 31.8 | |
| 10 | 510 | 343 | 323.8 | 63.5 | 276.2 | 277.4 | 276.2 | 152 | 86 | 111 | 273.0 | 431.8 | 16 | 34.9 | |
| 12 | 560 | 400 | 381.0 | 66.7 | 327.0 | 328.2 | 328.6 | 156 | 92 | 117 | 323.8 | 489.0 | 20 | 34.9 | |
| 14 | 605 | 432 | 412.8 | 69.9 | 359.2 | 360.2 | 360.4 | 165 | 94 | 127 | 355.6 | 527.0 | 20 | 38.1 | |
| 16 | 685 | 495 | 469.9 | 76.2 | 410.5 | 411.2 | 411.2 | 178 | 106 | 140 | 406.4 | 603.2 | 20 | 41.3 | |
| 18 | 745 | 546 | 533.4 | 82.6 | 461.8 | 462.3 | 462.0 | 184 | 117 | 152 | 457.0 | 654.0 | 20 | 44.5 | |
| 20 | 815 | 610 | 584.2 | 88.9 | 513.1 | 514.4 | 512.8 | 190 | 127 | 165 | 508.0 | 723.9 | 24 | 44.5 | |
| 24 | 940 | 718 | 692.2 | 101.6 | 616.0 | 616.0 | 614.4 | 203 | 140 | 184 | 610.0 | 838.2 | 24 | 50.8 | |
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