Steel Flange
Steel Flange
A steel flange is a mechanical component that is used to connect two pipes or pieces of equipment. It provides a strong, durable connection that helps to prevent leakage and ensures the safe flow of fluids or gases. Flanges are generally circular in shape and feature holes around their perimeter for bolts to securely fasten them together with a matching flange. This bolted connection is enhanced by gaskets or sealing rings that help to prevent leaks and maintain pressure within the system.
Flanges are available in various configurations, each designed for specific applications, pressure ratings, and installation environments. The primary function of a steel flange is to maintain the integrity of a system by providing a reliable means of joining pipe sections or equipment without compromising the system’s structural integrity.
Types of Steel Flanges
Materials Used in Steel Flanges
| Material Type | Common Grades | Applications | Key Features |
| Carbon Steel | ASTM A105, A350 LF2, A694 F42–F70, A36 | Oil & gas, pipelines, power plants | High strength, cost-effective, limited corrosion resistance |
| Stainless Steel | SS 304 / 304L, SS 316 / 316L, SS 321, SS 347 | Food, chemical, pharma, water treatment | Excellent corrosion resistance, durable, hygienic |
| Alloy Steel | ASTM A182 F1, F5, F9, F11, F22, F91 | Power generation, refineries, high-pressure systems | High strength, thermal resistance |
| Duplex / Super Duplex | UNS S31803, S32750, S32760 | Offshore, chemical, marine | Superior corrosion & chloride stress resistance |
| Nickel Alloys | Inconel 600 / 625, Monel 400, Hastelloy C22 / C276 | Extreme environments, chemical processing | Outstanding heat & acid resistance |
| Copper-Nickel | Cu-Ni 70/30, Cu-Ni 90/10 | Marine, desalination, shipbuilding | Seawater corrosion resistance, biofouling protection |
| Titanium | Grade 2, Grade 5 (Ti-6Al-4V) | Aerospace, marine, chemical | Exceptional strength-to-weight, corrosion resistant |
Dimensions & Weight
Steel Flange Dimension
| Nom. Pipe Size | O | T | TJ | R | X | #/Dia of Holesa | Bolt Circle Dia | B | B2b | B3 | H | L | L2 | L3c | r | D | Thr |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ½ | 3.50 | 0.38 | 0.44 | 1.38 | 1.19 | 4-0.62 | 2.38 | 0.88 | 0.62 | 0.90 | 0.84 | 0.56 | 1.81 | 0.62 | 0.12 | 0.38 | 0.62 |
| ¾ | 3.88 | 0.44 | 0.50 | 1.69 | 1.50 | 4-0.62 | 2.75 | 1.09 | 0.82 | 1.11 | 1.05 | 0.56 | 2.00 | 0.62 | 0.12 | 0.44 | 0.62 |
| 1 | 4.25 | 0.50 | 0.56 | 2.00 | 1.94 | 4-0.62 | 3.12 | 1.36 | 1.05 | 1.38 | 1.32 | 0.62 | 2.12 | 0.69 | 0.12 | 0.50 | 0.69 |
| 1¼ | 4.62 | 0.56 | 0.62 | 2.50 | 2.31 | 4-0.62 | 3.50 | 1.70 | 1.38 | 1.72 | 1.66 | 0.75 | 2.19 | 0.81 | 0.19 | 0.56 | 0.81 |
| 1½ | 5.00 | 0.62 | 0.69 | 2.88 | 2.56 | 4-0.62 | 3.88 | 1.95 | 1.61 | 1.97 | 1.90 | 0.81 | 2.38 | 0.88 | 0.25 | 0.62 | 0.88 |
| 2 | 6.00 | 0.69 | 0.75 | 3.62 | 3.06 | 4-0.75 | 4.75 | 2.44 | 2.07 | 2.46 | 2.38 | 0.94 | 2.44 | 1.00 | 0.31 | 0.69 | 1.00 |
| 2½ | 7.00 | 0.81 | 0.88 | 4.12 | 3.56 | 4-0.75 | 5.50 | 2.94 | 2.47 | 2.97 | 2.88 | 1.06 | 2.69 | 1.12 | 0.31 | 0.75 | 1.12 |
| 3 | 7.50 | 0.88 | 0.94 | 5.00 | 4.25 | 4-0.75 | 6.00 | 3.57 | 3.07 | 3.60 | 3.50 | 1.12 | 2.69 | 1.19 | 0.38 | 0.81 | 1.19 |
| 3½ | 8.50 | 0.88 | 0.94 | 5.50 | 4.81 | 8-0.75 | 7.00 | 4.07 | 3.55 | 4.10 | 4.00 | 1.19 | 2.75 | 1.25 | 0.38 | 0.88 | 1.25 |
| 4 | 9.00 | 0.88 | 0.94 | 6.19 | 5.31 | 8-0.75 | 7.50 | 4.57 | 4.03 | 4.60 | 4.50 | 1.25 | 2.94 | 1.31 | 0.44 | 0.94 | 1.31 |
| 5 | 10.00 | 0.88 | 0.94 | 7.31 | 6.44 | 8-0.88 | 8.50 | 5.66 | 5.05 | 5.69 | 5.56 | 1.38 | 3.44 | 1.44 | 0.44 | 0.94 | 1.44 |
| 6 | 11.00 | 0.94 | 1.00 | 8.50 | 7.56 | 8-0.88 | 9.50 | 6.72 | 6.07 | 6.75 | 6.63 | 1.50 | 3.44 | 1.56 | 0.50 | 1.06 | 1.56 |
| 8 | 13.50 | 1.06 | 1.12 | 10.62 | 9.69 | 8-0.88 | 11.75 | 8.72 | 7.98 | 8.75 | 8.63 | 1.69 | 3.94 | 1.75 | 0.50 | 1.25 | 1.75 |
| 10 | 16.00 | 1.12 | 1.19 | 12.75 | 12.00 | 12-1.00 | 14.25 | 10.88 | 10.02 | 10.92 | 10.75 | 1.88 | 3.94 | 1.94 | 0.50 | 1.31 | 1.94 |
| 12 | 19.00 | 1.19 | 1.25 | 15.00 | 14.38 | 12-1.00 | 17.00 | 12.88 | 12.00 | 12.92 | 12.75 | 2.12 | 4.44 | 2.19 | 0.50 | 1.56 | 2.19 |
| 14 | 21.00 | 1.31 | 1.38 | 16.25 | 15.75 | 12-1.12 | 18.75 | 14.14 | 13.25 | 14.18 | 14.00 | 2.19 | 4.94 | 3.12 | 0.50 | 1.63 | 2.25 |
| 16 | 23.50 | 1.38 | 1.44 | 18.50 | 18.00 | 16-1.12 | 21.25 | 16.16 | 15.25 | 16.19 | 16.00 | 2.44 | 4.94 | 3.44 | 0.50 | 1.75 | 2.50 |
| 18 | 25.00 | 1.50 | 1.56 | 21.00 | 19.88 | 16-1.25 | 22.75 | 18.18 | 17.25 | 18.20 | 18.00 | 2.62 | 5.44 | 3.81 | 0.50 | 1.94 | 2.69 |
| 20 | 27.50 | 1.62 | 1.69 | 23.00 | 22.00 | 20-1.25 | 25.00 | 20.20 | 19.25 | 20.25 | 20.00 | 2.81 | 5.62 | 4.06 | 0.50 | 2.13 | 2.88 |
| 22 | 29.50 | 1.75 | 1.81 | 25.25 | 24.25 | 20-1.38 | 27.25 | 22.22 | 21.25 | 22.25 | 22.00 | 3.07 | 5.82 | 4.25 | 0.50 | 2.38 | 3.13 |
| 24 | 32.00 | 1.81 | 1.88 | 27.25 | 26.12 | 20-1.38 | 29.50 | 24.25 | 23.25 | 24.25 | 24.00 | 3.19 | 5.94 | 4.38 | 0.50 | 2.50 | 3.25 |
Steel Flange Weight Chart
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
|---|---|---|---|---|---|---|---|
| 150 lb | ½ | 1 | 1 | 2 | 1 | 2 | 2 |
| ¾ | 2 | 2 | 2 | 2 | 2 | 2 | |
| 1 | 2 | 2 | 2 | 2 | 2 | 3 | |
| 1¼ | 3 | 3 | 3 | 3 | 3 | 3 | |
| 1½ | 3 | 3 | 3 | 3 | 4 | 4 | |
| 2 | 5 | 5 | 5 | 5 | 5 | 6 | |
| 2½ | 8 | 8 | 8 | 8 | 7 | 10 | |
| 3 | 9 | 9 | 9 | 9 | 9 | 11.5 | |
| 3½ | 11 | 12 | 11 | 11 | 13 | 12 | |
| 4 | 13 | 13 | 13 | 13 | 17 | 16.5 | |
| 5 | 15 | 15 | 15 | 15 | 20 | 21 | |
| 6 | 19 | 19 | 19 | 19 | 27 | 26 | |
| 8 | 30 | 30 | 30 | 30 | 47 | 42 | |
| 10 | 43 | 43 | 43 | 43 | 70 | 54 | |
| 12 | 64 | 64 | 64 | 64 | 123 | 88 | |
| 14 | 90 | 90 | 90 | 105 | 140 | 114 | |
| 16 | 106 | 98 | 98 | 140 | 180 | 140 | |
| 18 | 130 | 130 | 130 | 160 | 220 | 165 | |
| 20 | 165 | 165 | 165 | 195 | 285 | 197 | |
| 22 | 185 | 185 | 185 | 245 | 355 | 225 | |
| 24 | 220 | 220 | 220 | 275 | 430 | 268 | |
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
| 300 lb | ½ | 2 | 2 | 3 | 2 | 2 | 2 |
| ¾ | 3 | 3 | 3 | 3 | 3 | 3 | |
| 1 | 3 | 3 | 3 | 3 | 4 | 4 | |
| 1¼ | 4.5 | 4.5 | 4 | 4.5 | 6 | 5 | |
| 1½ | 6.5 | 6.5 | 6 | 6.5 | 7 | 7 | |
| 2 | 7 | 7 | 7 | 7 | 8 | 9 | |
| 2½ | 10 | 10 | 10 | 10 | 12 | 12 | |
| 3 | 13 | 14 | 13 | 14.5 | 16 | 18 | |
| 3½ | 17 | 17 | 17 | 17 | 21 | 20 | |
| 4 | 23.5 | 24 | 22 | 24 | 28 | 26.5 | |
| 5 | 29 | 31 | 28 | 28 | 37 | 36 | |
| 6 | 39 | 39 | 39 | 39 | 50 | 45 | |
| 8 | 58 | 58 | 58 | 58 | 81 | 69 | |
| 10 | 81 | 81 | 81 | 91 | 124 | 100 | |
| 12 | 115 | 115 | 115 | 140 | 185 | 142 | |
| 14 | 165 | 165 | 165 | 190 | 250 | 206 | |
| 16 | 210 | 220 | 190 | 234 | 315 | 250 | |
| 18 | 253 | 280 | 250 | 305 | 414 | 320 | |
| 20 | 315 | 325 | 315 | 375 | 515 | 400 | |
| 22 | 370 | 370 | 370 | 435 | 640 | 465 | |
| 24 | 490 | 490 | 475 | 550 | 800 | 580 | |
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
| 400 lb | ½ | 2 | 2 | 2 | 2 | 2 | 3 |
| ¾ | 3 | 3 | 3 | 3 | 3 | 3.5 | |
| 1 | 3.5 | 3.5 | 3.5 | 3.5 | 4 | 4 | |
| 1¼ | 4.5 | 4.5 | 4.5 | 4.5 | 6 | 4.5 | |
| 1½ | 6.5 | 6.5 | 6.5 | 6.5 | 8 | 8 | |
| 2 | 8 | 8 | 8 | 8 | 10 | 10 | |
| 2½ | 12 | 12 | 12 | 11 | 15 | 14 | |
| 3 | 15 | 15 | 15 | 14 | 20 | 18 | |
| 3½ | 21 | 21 | 21 | 20 | 29 | 26 | |
| 4 | 26 | 26 | 26 | 25 | 33 | 35 | |
| 5 | 31 | 31 | 31 | 29 | 44 | 43 | |
| 6 | 44 | 44 | 44 | 42 | 61 | 57 | |
| 8 | 67 | 67 | 67 | 64 | 100 | 89 | |
| 10 | 91 | 91 | 91 | 110 | 155 | 125 | |
| 12 | 130 | 130 | 130 | 152 | 226 | 175 | |
| 14 | 191 | 191 | 191 | 210 | 310 | 233 | |
| 16 | 253 | 253 | 253 | 280 | 398 | 295 | |
| 18 | 310 | 310 | 310 | 345 | 502 | 360 | |
| 20 | 378 | 378 | 378 | 420 | 621 | 445 | |
| 22 | 405 | 405 | 405 | 455 | 720 | 505 | |
| 24 | 539 | 539 | 539 | 615 | 936 | 640 | |
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
| 600 lb | ½ | 2 | 2 | 2 | 2 | 3 | 3 |
| ¾ | 3 | 3 | 3 | 3 | 4 | 4 | |
| 1 | 4 | 4 | 4 | 4 | 4 | 4 | |
| 1¼ | 5 | 5 | 5 | 5 | 6 | 6 | |
| 1½ | 7 | 7 | 7 | 7 | 8 | 8 | |
| 2 | 9 | 9 | 9 | 9 | 10 | 12 | |
| 2½ | 13 | 13 | 13 | 12 | 15 | 18 | |
| 3 | 16 | 16 | 16 | 15 | 20 | 23 | |
| 3½ | 21 | 21 | 21 | 20 | 29 | 26 | |
| 4 | 37 | 37 | 37 | 36 | 41 | 42 | |
| 5 | 63 | 63 | 63 | 63 | 68 | 68 | |
| 6 | 80 | 80 | 80 | 78 | 86 | 81 | |
| 8 | 115 | 115 | 115 | 112 | 140 | 120 | |
| 10 | 177 | 177 | 177 | 195 | 231 | 190 | |
| 12 | 215 | 215 | 215 | 240 | 295 | 226 | |
| 14 | 259 | 259 | 259 | 290 | 378 | 347 | |
| 16 | 366 | 366 | 366 | 400 | 527 | 481 | |
| 18 | 476 | 476 | 476 | 469 | 665 | 555 | |
| 20 | 612 | 612 | 612 | 604 | 855 | 690 | |
| 22 | 590 | 590 | 590 | 670 | 1000 | 720 | |
| 24 | 876 | 876 | 876 | 866 | 1250 | 977 | |
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
| 900 lb | ½ | 6 | 6 | 6 | 6 | 4 | 7 |
| ¾ | 6 | 6 | 6 | 6 | 6 | 7 | |
| 1 | 7.5 | 7.5 | 7.5 | 7.5 | 9 | 8.5 | |
| 1¼ | 10 | 10 | 10 | 10 | 10 | 10 | |
| 1½ | 14 | 14 | 14 | 14 | 14 | 14 | |
| 2 | 22 | 22 | 22 | 21 | 25 | 24 | |
| 2½ | 31 | 31 | 31 | 25 | 32 | 31 | |
| 3 | 36 | 36 | 36 | 29 | 35 | 36 | |
| 4 | 53 | 53 | 53 | 51 | 54 | 53 | |
| 5 | 83 | 83 | 83 | 81 | 87 | 86 | |
| 6 | 110 | 110 | 110 | 105 | 115 | 110 | |
| 8 | 172 | 172 | 172 | 190 | 200 | 187 | |
| 10 | 245 | 245 | 245 | 277 | 290 | 268 | |
| 12 | 326 | 326 | 326 | 371 | 415 | 372 | |
| 14 | 400 | 400 | 400 | 415 | 520 | 562 | |
| 16 | 459 | 459 | 459 | 488 | 619 | 685 | |
| 18 | 647 | 647 | 647 | 670 | 880 | 924 | |
| 20 | 792 | 792 | 792 | 868 | 1107 | 1164 | |
| 24 | 1480 | 1480 | 1480 | 1659 | 2099 | 2107 | |
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
| 1500 lb | ½ | 6 | 6 | 6 | 6 | 4 | 7 |
| ¾ | 6 | 6 | 6 | 6 | 6 | 7 | |
| 1 | 8 | 8 | 8 | 8 | 9 | 9 | |
| 1¼ | 10 | 10 | 10 | 10 | 10 | 10 | |
| 1½ | 14 | 14 | 14 | 14 | 14 | 14 | |
| 2 | 25 | 25 | 25 | 25 | 25 | 25 | |
| 2½ | 36 | 36 | 36 | 35 | 35 | 36 | |
| 3 | 48 | 48 | 48 | 47 | 48 | 48 | |
| 4 | 73 | 73 | 73 | 75 | 73 | 73 | |
| 5 | 132 | 132 | 132 | 140 | 140 | 132 | |
| 6 | 165 | 165 | 165 | 170 | 160 | 165 | |
| 8 | 260 | 260 | 260 | 286 | 302 | 275 | |
| 10 | 436 | 436 | 436 | 485 | 510 | 455 | |
| 12 | 667 | 667 | 667 | 749 | 775 | 690 | |
| 14 | 940 | 940 | 940 | 890 | 975 | 940 | |
| 16 | 1250 | 1250 | 1250 | 1250 | 1300 | 1250 | |
| 18 | 1625 | 1625 | 1625 | 1475 | 1750 | 1625 | |
| 20 | 2050 | 2050 | 2050 | 1775 | 2225 | 2050 | |
| 24 | 2825 | 2825 | 2825 | 2825 | 3625 | 3325 | |
| CLASS | Nominal Pipe Size | Slip On | Threaded | Socket Weld | Lap Joint | Blind | Weld Neck |
| 2500 lb | ½ | …. | 7 | …. | 7 | 7 | 8 |
| ¾ | …. | 9 | …. | 8 | 10 | 9 | |
| 1 | …. | 12 | …. | 12 | 12 | 13 | |
| 1¼ | …. | 18 | …. | 17 | 18 | 20 | |
| 1½ | …. | 25 | …. | 24 | 25 | 28 | |
| 2 | …. | 38 | …. | 37 | 39 | 42 | |
| 2½ | …. | 55 | …. | 53 | 56 | 52 | |
| 3 | …. | 83 | …. | 80 | 86 | 94 | |
| 4 | …. | 127 | …. | 122 | 133 | 146 | |
| 5 | …. | 210 | …. | 204 | 223 | 244 | |
| 6 | …. | 323 | …. | 314 | 345 | 378 | |
| 8 | …. | 485 | …. | 471 | 533 | 576 | |
| 10 | …. | 925 | …. | 897 | 1025 | 1068 | |
| 12 | …. | 1300 | …. | 1262 | 1464 | 1608 |
Materials Used for Steel Flanges
Steel flanges are made from various types of steel and alloys, depending on the intended application, environmental conditions, and pressure ratings. Some of the most common materials used for manufacturing steel flanges include:
- Carbon Steel
- Carbon steel flanges are among the most widely used due to their strength, affordability, and versatility. These flanges are suitable for low- to medium-pressure applications and can withstand high temperatures.
- Carbon steel flanges can be used in general-purpose applications, including water systems, oil and gas pipelines, and chemical industries.
- Stainless Steel
- Stainless steel flanges are highly resistant to corrosion, oxidation, and rust. These flanges are ideal for use in harsh environments where exposure to chemicals, moisture, or extreme temperatures is a concern.
- Common stainless steel grades used for flanges include 304, 316, and 904L, offering a balance of strength, durability, and corrosion resistance.
- Alloy Steel
- Alloy steel flanges are designed for high-strength applications and are often used in extreme environments. Alloy steels, such as AISI 4130 or AISI 4140, are chosen for their ability to withstand high temperatures, pressures, and aggressive chemicals.
- These flanges are commonly used in industries like aerospace, petrochemicals, and power generation.
- Duplex and Super Duplex Steel
- Duplex steel is a blend of ferritic and austenitic stainless steels that offer greater corrosion resistance and strength. Super duplex steel offers even better performance in aggressive environments, making it ideal for offshore oil and gas applications.
Applications
- Oil and Gas Industry
- In the oil and gas industry, steel flanges are used to connect pipelines, valves, and equipment, ensuring safe and secure transportation of crude oil, natural gas, and other related substances. Flanges help to maintain the integrity of the pipeline system under extreme pressures and temperatures.
- Chemical Processing
- Chemical plants rely on steel flanges to connect pipes and reactors safely. Chemical reactions often generate high temperatures and pressures, making it crucial to use flanges that can withstand such harsh conditions while preventing leaks.
- Power Generation
- In power plants, steel flanges are used to connect various components in steam, gas, and water systems. High-pressure and high-temperature resistance are key characteristics of the flanges used in these settings.
- Water Treatment
- Steel flanges are commonly used in municipal water systems, desalination plants, and water treatment facilities. They provide reliable connections for pumps, filters, and other equipment that are critical to maintaining water quality and flow.
- Food and Beverage
- Food-grade stainless steel flanges are used to connect equipment in the food and beverage industry. These flanges ensure that there is no contamination in the product while maintaining hygienic conditions in processing systems.
