Carbon Steel Flange
Carbon Steel Flange
A Carbon Steel Flange is a forged or cast ring of steel designed to connect sections of pipe or join pipe to a pressure vessel, pump, valve, or any other piece of equipment. Carbon steel, primarily composed of iron and carbon, provides flanges with high strength, wear resistance, and the ability to withstand extreme temperature and pressure conditions.
Carbon Steel Flanges are essential components in various industries like oil & gas, petrochemicals, power generation, shipbuilding, water treatment, and more. Their excellent mechanical properties and cost-effectiveness make them one of the most widely used flange types across the globe.
Key Features of Carbon Steel Flanges
- High Strength: Carbon steel flanges are known for their tensile strength and ability to endure heavy loads and high-pressure environments.
- Corrosion Resistance (With Coatings): While carbon steel is not naturally corrosion-resistant like stainless steel, protective coatings such as galvanizing or painting can improve corrosion performance.
- Excellent Weldability: Carbon steel flanges are easily weldable, making them ideal for joining with various piping systems.
- Temperature Tolerance: Suitable for high and low-temperature applications, including cryogenic conditions when treated accordingly.
- Cost-Effective: Offers significant savings compared to alloy or stainless steel flanges without compromising on performance.
Types of Carbon Steel Flanges
Carbon Steel Flange Grades & Standard
| Grade | Standard | Description |
| ASTM A105 | ASME/ASTM | Most widely used forged carbon steel flange. Ideal for ambient- and high-temperature service in pressure systems. |
| ASTM A350 LF2 | ASME/ASTM | Low-temperature carbon steel flange grade. Used in cryogenic and sub-zero applications. |
| ASTM A694 F42 / F46 / F52 / F60 / F65 / F70 | ASME/ASTM | High-strength carbon steel flanges used in high-pressure transmission service (especially pipelines). Grade increases with strength requirements. |
| ASTM A516 Gr. 60 / 70 | ASME/ASTM | Used in pressure vessels; sometimes used for flanges in moderate/high-temperature service. |
| ASTM A36 | ASME/ASTM | Structural carbon steel grade. Sometimes used in low-pressure applications. |
| IS 2062 Gr A/B/C | Indian Standard | Structural/mild steel grades, occasionally used for flanges in low-pressure pipelines and general fabrication. |
| EN 1092-1 (S235JR / S275JR / S355JR) | European Standard | Structural carbon steels commonly used in Europe for flanges and fittings. |
Carbon Steel Flange Dimensions & Pressure Ratings
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
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
Pressure Ratings:
- Class 150
- Class 300
- Class 600
- Class 900
- Class 1500
- Class 2500
Applications
- Oil & Gas Transmission Lines
- Refineries & Petrochemical Plants
- Power Generation (Thermal & Nuclear)
- Chemical Processing Plants
- Water & Wastewater Management
- Shipbuilding & Marine Applications
- Steel Plants & Fabrication Units
Surface Coatings & Protection
To enhance corrosion resistance and longevity, carbon steel flanges can be supplied with the following surface treatments:
- Black Paint
- Anti-rust Oil
- Galvanized (Hot Dip or Electro)
- Epoxy Coating
- FBE Coating (Fusion Bonded Epoxy)