Threaded pipe flanges are commonly used in various industries for pipe connections where welding is not an option. These flanges feature an internally threaded hole that pairs with a pipe with matching threads, providing a simple and reliable connection. Unlike welded flanges, threaded flanges do not require welding, making them ideal for applications in environments where welding is prohibited or impractical, such as certain on-site installations or in systems with heat-sensitive components. Threaded flanges are widely used in industries including oil and gas, chemical processing, and water treatment.
- Material: Carbon steel, stainless steel, alloy steel, etc.
- Size: Common sizes range from 1/2″ to 24″.
- Pressure Rating: 150#, 300#, 600#, etc.
- Thread Type: NPT (American) or BSP (British).
Introduction
Threaded flanges provide a weld-free piping connection solution widely used in applications requiring quick installation or disassembly. Suitable for low-pressure piping systems, they offer straightforward installation and are particularly well-suited for environments with welding restrictions. Typically manufactured from high-strength materials, threaded flanges ensure stable and durable connections, though they are not recommended for high-temperature or high-pressure conditions. Proper selection of threaded flanges can significantly enhance system maintenance efficiency and safety.
Class 150 lb Threaded Flange Specification
Threaded pipe flanges are categorized by pressure rating into Class 150lb, Class 300lb, Class 400lb, Class 600lb, Class 900lb, Class 1500lb, and Class 2500lb. Below is the parameter table:
| Size Range | 1/2” – 24” / DN15 – DN600 |
| Pressure Rating | Class 150，300，600，900，1500，2500 |
| Standard | ASME B16.5 |
| Carbon Steel | ASTM A105, 20# |
| Low-Temperature Steel | ASTM A350 LF2, 16Mn |
| Pipeline Steel | ASTM A694 F42 / 46 / 56 / 60 / 65 |
| Alloy Steel | ASTM A182 F11 / 12 / 5 / 9 / 91 / 92 |
| Stainless Steel | ASTM A182 F304/304L/304H, 316/316L, 310S, 317,347,904L |
| Duplex Stainless Steel | ASTM A182 F51, F53, F44 |
Class 150 lb Socket Weld Flange Dimensions
| NPS | A | C | D | E | F | G | H | I | J | W |
| inch | inch | inch | inch | inch | inch | No. of Holes | inch | inch | kg/pc | |
| mm | mm | mm | mm | mm | mm | mm | mm | |||
| 1/2 | 3.500 | 0.440 | 0.620 | 0.620 | 1.190 | 1.380 | 4 | 0.620 | 2.380 | 0.39 |
| 88.9 | 11.20 | 15.70 | 15.70 | 30.20 | 35.10 | 15.70 | 60.45 | |||
| 3/4 | 3.880 | 0.500 | 0.620 | 0.620 | 1.500 | 1.690 | 4 | 0.620 | 2.750 | 0.56 |
| 98.60 | 12.70 | 15.70 | 15.70 | 38.10 | 42.90 | 15.70 | 69.85 | |||
| 1 | 4.250 | 0.560 | 0.690 | 0.690 | 1.940 | 2.000 | 4 | 0.620 | 3.120 | 0.78 |
| 108.0 | 14.20 | 17.50 | 17.50 | 49.30 | 50.80 | 15.70 | 79.25 | |||
| 1¼ | 4.620 | 0.620 | 0.810 | 0.810 | 2.310 | 2.500 | 4 | 0.620 | 3.500 | 1.03 |
| 117.3 | 15.70 | 20.60 | 20.60 | 58.70 | 63.50 | 15.70 | 88.90 | |||
| 1½ | 5.000 | 0.690 | 0.880 | 0.880 | 2.560 | 2.880 | 4 | 0.620 | 3.880 | 1.32 |
| 127.0 | 17.50 | 22.40 | 22.30 | 65.00 | 73.15 | 15.70 | 98.60 | |||
| 2 | 6.000 | 0.750 | 1.000 | 1.000 | 3.060 | 3.620 | 4 | 0.750 | 4.750 | 2.06 |
| 152.4 | 19.10 | 25.40 | 25.40 | 77.70 | 91.90 | 0.750 | 4.750 | |||
| 2½ | 7.000 | 0.880 | 1.120 | 1.120 | 3.560 | 4.120 | 4 | 0.750 | 5.500 | 3.28 |
| 177.8 | 22.40 | 28.40 | 28.40 | 90.40 | 104.6 | 19.10 | 139.7 | |||
| 3 | 7.500 | 0.940 | 1.190 | 1.190 | 4.250 | 5.000 | 4 | 0.750 | 6.000 | 3.85 |
| 190.5 | 23.90 | 30.20 | 30.20 | 108.0 | 127.0 | 19.10 | 152.4 | |||
| 3½ | 8.500 | 0.940 | 1.250 | 1.250 | 4.810 | 5.500 | 8 | 0.750 | 7.000 | 4.81 |
| 215.9 | 23.90 | 31.75 | 31.75 | 122.2 | 139.7 | 19.10 | 177.8 | |||
| 4 | 9.000 | 0.940 | 1.310 | 1.310 | 5.310 | 6.190 | 8 | 0.750 | 7.500 | 5.30 |
| 228.6 | 23.90 | 33.30 | 33.30 | 134.9 | 157.2 | 19.10 | 190.5 | |||
| 5 | 10.00 | 0.940 | 1.440 | 1.440 | 6.440 | 7.310 | 8 | 0.880 | 8.500 | 6.07 |
| 254.0 | 23.90 | 36.60 | 36.60 | 163.6 | 185.7 | 22.4 | 215.9 | |||
| 6 | 11.00 | 1.000 | 1.560 | 1.560 | 7.560 | 8.500 | 8 | 0.880 | 9.5 | 7.45 |
| 279.4 | 25.40 | 39.60 | 39.60 | 192.0 | 215.9 | 22.40 | 241.3 | |||
| 8 | 13.50 | 1.120 | 1.750 | 1.750 | 9.690 | 10.62 | 8 | 0.880 | 11.75 | 12.1 |
| 342.9 | 28.40 | 44.50 | 44.50 | 246.1 | 269.7 | 22.40 | 298.5 | |||
| 10 | 16.00 | 1.190 | 1.940 | 1.940 | 12.00 | 12.75 | 12 | 1.000 | 14.25 | 16.5 |
| 406.4 | 30.20 | 49.30 | 49.30 | 304.8 | 323.9 | 25.40 | 362.0 | |||
| 12 | 19.00 | 1.250 | 2.190 | 2.190 | 14.38 | 15.00 | 12 | 1.000 | 17.00 | 26.2 |
| 482.6 | 31.75 | 55.60 | 55.60 | 365.3 | 381.0 | 25.40 | 431.8 | |||
| 14 | 21.00 | 1.380 | 2.250 | 2.250 | 15.75 | 16.25 | 12 | 1.120 | 18.75 | 34.6 |
| 533.4 | 35.10 | 57.15 | 57.15 | 400.1 | 412.7 | 28.40 | 476.3 | |||
| 16 | 23.50 | 1.440 | 2.500 | 2.500 | 18.00 | 18.50 | 16 | 1.120 | 21.25 | 44.8 |
| 596.9 | 36.60 | 63.50 | 63.50 | 457.2 | 469.9 | 28.40 | 539.8 | |||
| 18 | 25.00 | 1.560 | 2.690 | 2.690 | 19.88 | 21.00 | 16 | 1.250 | 22.75 | 48.9 |
| 635.0 | 39.60 | 68.30 | 68.30 | 505.0 | 533.4 | 31.75 | 577.9 | |||
| 20 | 27.50 | 1.690 | 2.880 | 2.880 | 22.00 | 23.00 | 20 | 1.250 | 25.00 | 61.9 |
| 698.5 | 42.90 | 73.15 | 73.15 | 558.8 | 584.2 | 31.75 | 635.0 | |||
| 24 | 32.00 | 1.880 | 3.250 | 3.250 | 26.12 | 27.25 | 20 | 1.380 | 29.50 | 86.9 |
| 812.8 | 47.80 | 82.60 | 82.60 | 663.4 | 692.2 | 35.10 | 749.3 |
Considerations for Use
While threaded flanges offer convenience and flexibility, they are not suitable for all conditions. For systems with high-pressure or extreme temperature variations—particularly temperatures above 260°C or below -45°C—threaded flanges may not provide adequate sealing and could result in leakage. Therefore, careful consideration of operational conditions is necessary before selecting a threaded pipe flange. For most general applications, however, threaded flanges provide a durable, cost-effective solution for pipe connections where welding is not feasible.
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