Kalp Alloys is a leading manufacturer and supplier of Class 1500 Flanges (also known as 1500 lb flanges or 1500# flanges) conforming to ASME B16.5 standard. We supply Class 1500 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 1500 flange is a pressure-class designation under the ASME B16.5 standard (Steel Pipe Flanges and Flanged Fittings). The “1500” refers to the pressure class — built for ultra-high-pressure and extreme-temperature piping systems. Class 1500 flanges are rated at approximately 3705 psi (255 bar) at ambient temperature (38°C) for carbon steel.
They are widely used in high-pressure steam systems, hydrocracking units, deep-water oil & gas pipelines, power plants, and critical refinery piping where extreme operating conditions demand the highest structural integrity. Because of their exceptionally thick bodies, heavy bolt patterns, and superior pressure capacity, ASME B16.5 Class 1500 flanges are specified for the most severe service conditions in industrial piping.
| NPS | Outside Diam. D | Diam. of Hub X | OD of RF G | Thickness (Min) t | Bore | Length Thru Hub | 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 | 120 | 38 | 34.9 | 22.3 | See Note (1) To be specified by Purchaser | 22.2 | 22.9 | 23.6 | 60 | 32 | 32 | 82.6 | 4 | 22.2 |
| 3/4 | 130 | 44 | 42.9 | 25.4 | 27.7 | 28.2 | 29.0 | 70 | 35 | 35 | 88.9 | 4 | 22.2 | |
| 1 | 150 | 52 | 50.8 | 28.6 | 34.5 | 34.9 | 35.8 | 73 | 41 | 41 | 101.6 | 4 | 25.4 | |
| 1 1/4 | 160 | 64 | 63.5 | 28.6 | 43.2 | 43.7 | 44.4 | 73 | 41 | 41 | 111.1 | 4 | 25.4 | |
| 1 1/2 | 180 | 70 | 73.0 | 31.8 | 49.5 | 50.0 | 50.6 | 83 | 44 | 44 | 123.8 | 4 | 28.6 | |
| 2 | 215 | 105 | 92.1 | 38.1 | 61.9 | 62.5 | 63.5 | 102 | 57 | 57 | 165.1 | 8 | 25.4 | |
| 2 1/2 | 245 | 124 | 104.8 | 41.3 | 74.6 | 75.4 | 76.2 | 105 | 64 | 64 | 190.5 | 8 | 28.6 | |
| 3 | 265 | 133 | 127.0 | 47.7 | – | 91.4 | – | 117 | – | 73 | 203.2 | 8 | 31.8 | |
| 4 | 310 | 162 | 157.2 | 54.0 | – | 116.8 | – | 124 | – | 90 | 241.3 | 8 | 34.9 | |
| 5 | 375 | 197 | 185.7 | 73.1 | – | 144.4 | – | 156 | – | 105 | 292.1 | 8 | 41.3 | |
| 6 | 395 | 229 | 215.9 | 82.6 | – | 171.4 | – | 171 | – | 119 | 317.5 | 12 | 38.1 | |
| 8 | 485 | 292 | 269.9 | 92.1 | – | 222.2 | – | 213 | – | 143 | 393.7 | 12 | 44.5 | |
| 10 | 585 | 368 | 323.8 | 108.0 | – | 277.4 | – | 254 | – | 178 | 482.6 | 12 | 50.8 | |
| 12 | 675 | 451 | 381.0 | 123.9 | – | 328.2 | – | 283 | – | 219 | 571.5 | 16 | 54.0 | |
| 14 | 750 | 495 | 412.8 | 133.4 | – | 360.2 | – | 298 | – | 241 | 635.0 | 16 | 60.3 | |
| 16 | 825 | 552 | 469.9 | 146.1 | – | 411.2 | – | 311 | – | 260 | 704.8 | 16 | 66.7 | |
| 18 | 915 | 597 | 533.4 | 162.0 | – | 462.3 | – | 327 | – | 276 | 774.7 | 16 | 73.0 | |
| 20 | 985 | 641 | 584.2 | 177.8 | – | 514.4 | – | 356 | – | 292 | 831.8 | 16 | 79.4 | |
| 24 | 1170 | 762 | 692.2 | 203.2 | – | 616.0 | – | 406 | – | 330 | 990.6 | 16 | 92.1 | |
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