Views: 5 Author: Site Editor Publish Time: 2026-06-18 Origin: Site
In industrial piping systems, flanged connections play a critical role. For high-pressure, high-temperature, and corrosive media services, the ASME B16.5 stainless steel weld neck flange is a top choice across petrochemical, marine, and power industries, thanks to its strong sealing performance and structural integrity. This article breaks down the technical essentials and selection criteria from two angles: the ASME B16.5 standard and ASTM A182 material specifications.
ASME B16.5, titled *Pipe Flanges and Flange Fittings NPS 1/2 through NPS 24*, covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and bore sizing. It applies to sizes from NPS 1/2″ to 24″ (DN15 to DN600) across seven pressure classes: 150, 300, 400, 600, 900, 1500, and 2500. Note that Class 2500 is limited to NPS 1/2″ through 12″.
Types | WN Flange、SO Flange、SW Flange、TH Flange、LAPJ Flange、Blind Flange |
Sealing Surface | RF, FF, RTJ |
Size | 1/2" - 60" / DN15 - DN1500 |
Standard | ASME B16.5 ASME B16.47 A/B |
Stainless Steel | ASTM A182 F304/304L/304H, 316/316L, 310S, 317,347,904L |
Duplex Stainless Steel | ASTM A182 F51, F53, F44 |
Dimension:NPS 1/2 to NPS 24.
Pressure:Class 150, 300, 400, 600, 900, 1500, and 2500.
Types:weld neck flange, slip on flange, socket weld flange, threaded, lap joint flange, and blind flange.
Attention: Flange diameter＞DN600, refer to specialized standards for large-sized flanges such as ASME B16.47.
ASME B16.5 includes several flange types.
Types of ASME B16.5 Flange | Features |
Weld Neck Flange | tapered hub / butt-welded / smooth stress transition / highest strength |
Slip-On Flange | slides over pipe end / easy installation / medium-low pressure |
Socket Weld Flange | pipe inserts into socket / small diameter / high-pressure service |
Threaded Flange | threaded connection / no welding / low-pressure non-critical |
Lap Joint Flange | used with stub end / easy disassembly / flexible alignment |
Blind Flange | closes pipe end / no center bore / pipeline isolation |
The weld neck flange stands out with its tapered hub, which smoothly transfers stress between the flange and pipe. This design delivers superior fatigue strength and bending rigidity. The butt-welded joint matches the parent material's strength, ensuring reliable sealing even under extreme temperature swings and high pressure.
Pressure | Maximum allowable pressure at 100 ° F (psi) | Applicable specification range |
Class 150 | 285 | NPS 1/2 – 24 |
Class 300 | 740 | NPS 1/2 – 24 |
Class 400 | 990 | NPS 1/2 – 24 |
Class 600 | 1,480 | NPS 1/2 – 24 |
Class 900 | 2,220 | NPS 1/2 – 24 |
Class 1500 | 3,705 | NPS 1/2 – 24 |
Class 2500 | 6,175 | NPS 1/2 – 12 |
Always verify against the standard's pressure-temperature tables for your actual operating temperature.
Critical dimensions for weld neck flanges include outside diameter (OD), thickness (T), bolt circle diameter (PCD), number and size of bolt holes, hub diameter, and bore size.
The bore is specified by the purchaser based on pipe wall thickness.
Size Range: 1/2 inch through 24 inches (NPS 1/2 – NPS 24).
Sealing Face: Raised Face (RF), Flat Face (FF), Male & Female Face (MFM), Tongue & Groove Face (TG), Ring Joint Face (RJ), etc. The most commonly used type is the Raised Face (RF) weld neck flange.
Pressure Classes: Seven classes including Class 150, 300, 400, 600, 900, 1500, and 2500.
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 88.90 | 15.70 | 11.20 | 47.80 | 21.30 | 30.20 | 35.00 | 4 | 15.70 | 60.45 | 0.48 |
| 3/4 | 26.70 | 98.60 | 20.80 | 12.70 | 52.30 | 26.70 | 38.10 | 42.90 | 4 | 15.70 | 69.85 | 0.71 |
| 1 | 33.40 | 108.0 | 26.70 | 14.20 | 55.60 | 33.50 | 49.30 | 50.80 | 4 | 15.70 | 79.25 | 1.01 |
| 11/4 | 42.20 | 117.3 | 35.10 | 15.70 | 57.15 | 42.20 | 58.70 | 63.50 | 4 | 15.70 | 88.90 | 1.33 |
| 11/2 | 48.30 | 127.0 | 40.90 | 17.50 | 62.00 | 48.30 | 65.00 | 73.15 | 4 | 15.70 | 98.60 | 1.72 |
| 2 | 60.30 | 152.4 | 52.60 | 19.10 | 63.50 | 60.45 | 77.70 | 91.90 | 4 | 19.10 | 120.7 | 2.58 |
| 21/2 | 73.00 | 177.8 | 62.70 | 22.40 | 69.85 | 73. 15 | 90.4 | 104.6 | 4 | 19.10 | 139.7 | 4.11 |
| 3 | 88.90 | 190.5 | 78.00 | 23.90 | 69.85 | 88.90 | 108.0 | 127.0 | 4 | 19.10 | 152.4 | 4.92 |
| 31/2 | 101.6 | 215.9 | 90.20 | 23.90 | 71.40 | 101.6 | 122.2 | 139.7 | 8 | 19.10 | 177.8 | 6.08 |
| 4 | 114.3 | 228.6 | 102.40 | 23.90 | 76.20 | 114.3 | 134.9 | 157.2 | 8 | 19.10 | 190.5 | 6.84 |
| 5 | 141.3 | 254.0 | 128.3 | 23.90 | 88.90 | 141.2 | 163.6 | 185.7 | 8 | 22.40 | 215.9 | 8.56 |
| 6 | 168.3 | 279.4 | 154.2 | 25.40 | 88.90 | 168.4 | 192.0 | 215.9 | 8 | 22.40 | 241.3 | 10.6 |
| 8 | 219.1 | 342.9 | 202.7 | 28.40 | 101.6 | 219.2 | 246.1 | 269.7 | 8 | 22.40 | 298.5 | 17.6 |
| 10 | 273.0 | 406.4 | 254.5 | 30.20 | 101.6 | 273.0 | 304.8 | 323.8 | 12 | 25.40 | 362.0 | 24.0 |
| 12 | 323.8 | 482.6 | 304.8 | 31.75 | 114.3 | 323.8 | 365.3 | 381.0 | 12 | 25.40 | 431.8 | 36.5 |
| 14 | 355.6 | 533.4 | To be specified by the Purchaser | 35.10 | 127.0 | 355.6 | 400.1 | 412.7 | 12 | 28.40 | 476.3 | 48.4 |
| 16 | 406.4 | 596.9 | 36.60 | 127.0 | 406.4 | 475.2 | 469.9 | 16 | 28.40 | 539.8 | 60.6 | |
| 18 | 457.2 | 635.0 | 39.60 | 139.7 | 457.2 | 505.0 | 533.4 | 16 | 31.75 | 577.9 | 68.3 | |
| 20 | 508.0 | 698.5 | 42.90 | 144.5 | 508.0 | 558.8 | 584.2 | 20 | 31.75 | 635.0 | 84.5 | |
| 24 | 609.6 | 812.8 | 47.80 | 152.4 | 609.6 | 663.4 | 692.1 | 20 | 35.10 | 749.3 | 115 | |
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 95.20 | 15.70 | 14.20 | 52.30 | 21.30 | 38.10 | 35.00 | 4 | 15.70 | 66.55 | 0.75 |
| 3/4 | 26.70 | 117.3 | 20.80 | 15.70 | 57.15 | 26.70 | 47.70 | 42.90 | 4 | 19.00 | 82.50 | 1.26 |
| 1 | 33.40 | 123.9 | 26.70 | 17.50 | 62.00 | 33.50 | 53.80 | 50.80 | 4 | 19.00 | 88.90 | 1.52 |
| 1 1/4 | 42.20 | 133.3 | 35.10 | 19.00 | 65.00 | 42.20 | 63.50 | 63.50 | 4 | 19.00 | 98.50 | 2.03 |
| 1 1/2 | 48.30 | 155.4 | 40.90 | 20.60 | 68.30 | 48.30 | 69.85 | 73. 15 | 4 | 22.30 | 114.3 | 2.89 |
| 2 | 60.30 | 165. 1 | 52.60 | 22.30 | 69.85 | 60.45 | 84.00 | 91.90 | 8 | 19.00 | 127.0 | 3.4 |
| 2 1/2 | 73.00 | 190.5 | 62.70 | 25.40 | 76.20 | 73.15 | 100.0 | 104.6 | 8 | 22.30 | 149.3 | 5.17 |
| 3 | 88.90 | 209.5 | 78.00 | 28.40 | 79.25 | 88.90 | 117.3 | 127.0 | 8 | 22.30 | 168.1 | 6.93 |
| 3 1/2 | 101.6 | 228.6 | 90.20 | 30.20 | 81.00 | 101.6 | 133.3 | 139.7 | 8 | 22.30 | 184.1 | 8.67 |
| 4 | 114.3 | 254.0 | 102.4 | 31.70 | 85.80 | 114.3 | 146.0 | 157.2 | 8 | 22.30 | 200.1 | 11.2 |
| 5 | 141.3 | 279.4 | 128.3 | 35.00 | 98.50 | 141.2 | 177.8 | 185.7 | 8 | 22.30 | 234.9 | 15.1 |
| 6 | 168.3 | 317.5 | 154.2 | 36.50 | 98.50 | 168.4 | 206.2 | 215.9 | 12 | 22.30 | 269.7 | 19.1 |
| 8 | 219.1 | 381.0 | 202.7 | 41.10 | 111.2 | 219.2 | 260.3 | 269.7 | 12 | 25.40 | 330.2 | 29.9 |
| 10 | 273.0 | 444.5 | 254.5 | 47.70 | 117.3 | 273.0 | 320.5 | 323.8 | 16 | 28.40 | 387.3 | 42.7 |
| 12 | 323.8 | 520.7 | 304.8 | 50.80 | 130.0 | 323.8 | 374.6 | 381.0 | 16 | 31.70 | 450.8 | 61.8 |
| 14 | 355.6 | 584.2 | To be specified by the Purchaser | 53.80 | 142.7 | 355.6 | 425.4 | 412.7 | 20 | 31.70 | 514.3 | 85.8 |
| 16 | 406.4 | 647.7 | 57.15 | 146.0 | 406.4 | 482.6 | 469.9 | 20 | 35.00 | 571.5 | 106 | |
| 18 | 457.2 | 711.2 | 60.45 | 158.7 | 457.2 | 533.4 | 533.4 | 24 | 35.00 | 628.6 | 131 | |
| 20 | 508.0 | 774.7 | 63.50 | 162.0 | 508.0 | 587.2 | 584.2 | 24 | 35.00 | 685.8 | 158 | |
| 24 | 609.6 | 914.4 | 69.85 | 168.1 | 609.6 | 701.5 | 692.1 | 24 | 41.10 | 812.8 | 230 | |
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 95.30 | To be specified by the Purchaser | 14.20 | 52.30 | 21.30 | 38.10 | 35.00 | 4 | 15.70 | 66.55 | 0.87 |
| 3/4 | 26.70 | 117.3 | 15.70 | 57.15 | 26.70 | 47.80 | 42.90 | 4 | 19.10 | 82.60 | 1.45 | |
| 1 | 33.40 | 124.0 | 17.50 | 62.00 | 33.50 | 53.80 | 50.80 | 4 | 19.10 | 88.90 | 1.76 | |
| 11/4 | 42.20 | 133.4 | 20.60 | 66.55 | 42.20 | 63.50 | 63.50 | 4 | 19.10 | 98.60 | 2.49 | |
| 11/2 | 48.30 | 155.4 | 22.40 | 69.85 | 48.30 | 69.85 | 73.15 | 4 | 22.40 | 114.3 | 3.49 | |
| 2 | 60.30 | 165.1 | 25.40 | 73.15 | 60.45 | 84.10 | 91.90 | 8 | 19.10 | 127.0 | 4.36 | |
| 21/2 | 73.00 | 190.5 | 28.40 | 79.25 | 73.15 | 100.1 | 104.6 | 8 | 22.40 | 149.4 | 6.43 | |
| 3 | 88.90 | 209.6 | 31.75 | 82.60 | 88.90 | 117.3 | 127.0 | 8 | 22.40 | 168. 1 | 8.53 | |
| 31/2 | 101.6 | 228.6 | 35.10 | 85.90 | 101.6 | 133.4 | 139.7 | 8 | 25.40 | 84.2 | 10.7 | |
| 4 | 114.3 | 254.0 | 35.10 | 88.90 | 114.3 | 146.1 | 157.2 | 8 | 25.40 | 200.2 | 12.8 | |
| 5 | 141.3 | 279.4 | 38.10 | 101.6 | 141.2 | 177.8 | 185.7 | 8 | 25.40 | 235.0 | 16.9 | |
| 6 | 168.3 | 317.5 | 41.10 | 103.1 | 168.4 | 206.2 | 215.9 | 12 | 25.40 | 269.7 | 22.0 | |
| 8 | 219. 1 | 381.0 | 47.80 | 117.3 | 219.2 | 260.4 | 269.7 | 12 | 28.40 | 330.2 | 34.7 | |
| 10 | 273.0 | 444.5 | 53.80 | 124.0 | 273.0 | 320.5 | 323.8 | 16 | 31.75 | 387.4 | 48.5 | |
| 12 | 323.8 | 520.7 | 57.15 | 5.380 136.7 | 323.8 | 374.7 | 381.0 | 16 | 35.10 | 450.9 | 69.6 | |
| 14 | 355.6 | 584.2 | 60.45 | 149.4 | 355.6 | 425.5 | 412.7 | 20 | 35.10 | 514.4 | 95.5 | |
| 16 | 406.4 | 647.7 | 63.50 | 152.4 | 406.4 | 482.6 | 469.9 | 20 | 38.10 | 571.5 | 118 | |
| 18 | 457.2 | 711.2 | 66.55 | 165.1 | 457.2 | 533.4 | 533.4 | 24 | 38.10 | 628.7 | 145 | |
| 20 | 508.0 | 774.7 | 69.85 | 168.1 | 508.0 | 587.2 | 584.2 | 24 | 41.10 | 685.8 | 173 | |
| 24 | 609.6 | 914.4 | 76.20 | 174.8 | 609.6 | 701.5 | 692.1 | 24 | 47.80 | 812.8 | 249 | |
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 95.30 | To be specified by the Purchaser | 14.20 | 52.30 | 21.30 | 38.10 | 35.00 | 4 | 15.70 | 66.55 | 0.87 |
| 3/4 | 26.70 | 117.3 | 15.70 | 57.15 | 26.70 | 47.80 | 42.90 | 4 | 19.10 | 82.60 | 1.45 | |
| 1 | 33.40 | 124.0 | 17.50 | 62.00 | 33.50 | 53.80 | 50.80 | 4 | 19.10 | 88.90 | 1.76 | |
| 11/4 | 42.20 | 133.4 | 20.60 | 66.55 | 42.20 | 63.50 | 63.50 | 4 | 19.10 | 98.60 | 2.49 | |
| 11/2 | 48.30 | 155.4 | 22.40 | 69.85 | 48.30 | 69.85 | 73. 15 | 4 | 22.40 | 114.3 | 3.49 | |
| 2 | 60.30 | 165. 1 | 25.40 | 73.15 | 60.45 | 84.10 | 91.90 | 8 | 19.10 | 127.0 | 4.36 | |
| 21/2 | 73.00 | 190.5 | 28.40 | 79.25 | 73.15 | 100.1 | 104.6 | 8 | 22.40 | 149.4 | 6.43 | |
| 3 | 88.90 | 209.6 | 31.75 | 82.60 | 88.90 | 117.3 | 127.0 | 8 | 22.40 | 168.1 | 8.53 | |
| 31/2 | 101.6 | 228.6 | 35.10 | 85.90 | 101.6 | 133.4 | 139.7 | 8 | 25.40 | 184.2 | 10.7 | |
| 4 | 114.3 | 273. 1 | 38.10 | 101.6 | 114.3 | 152.4 | 157.2 | 8 | 25.40 | 215.9 | 17.4 | |
| 5 | 141.3 | 330.2 | 44.50 | 114.3 | 141.2 | 189.0 | 185.7 | 8 | 28.40 | 266.7 | 29.2 | |
| 6 | 168.3 | 355.6 | 47.80 | 117.3 | 168.4 | 222.3 | 215.9 | 12 | 28.40 | 292.1 | 34.9 | |
| 8 | 219.1 | 419. 1 | 55.60 | 133.4 | 219.2 | 273.1 | 269.7 | 12 | 31.75 | 349.3 | 53.9 | |
| 10 | 273.0 | 508.0 | 63.50 | 152.4 | 273.0 | 342.9 | 323.8 | 16 | 35.10 | 431.8 | 86.5 | |
| 12 | 323.8 | 558.8 | 66.55 | 155.4 | 323.8 | 400.1 | 381.0 | 20 | 35.10 | 489.0 | 103 | |
| 14 | 355.6 | 603.3 | 69.85 | 165.1 | 355.6 | 431.8 | 412.7 | 20 | 38.10 | 527.1 | 122 | |
| 16 | 406.4 | 685.8 | 76.20 | 177.8 | 406.4 | 495.3 | 469.9 | 20 | 41.10 | 603.3 | 170 | |
| 18 | 457.2 | 743.0 | 82.60 | 184.2 | 457.2 | 546.1 | 533.4 | 20 | 44.50 | 654.1 | 204 | |
| 20 | 508.0 | 812.8 | 88.90 | 190.5 | 508.0 | 609.6 | 584.2 | 24 | 44.50 | 723.9 | 254 | |
| 24 | 609.6 | 939.8 | 101.6 | 203.2 | 609.6 | 717.6 | 692.1 | 24 | 50.80 | 838.2 | 358 | |
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 120.6 | To be specified by the Purchaser | 22.30 | 60.45 | 21.30 | 38.10 | 35.00 | 4 | 22.30 | 82.50 | 1.87 |
| 3/4 | 26.70 | 130.0 | 25.40 | 69.85 | 26.70 | 44.00 | 42.90 | 4 | 22.30 | 88.90 | 2.56 | |
| 1 | 33.40 | 149.3 | 28.40 | 73.15 | 33.50 | 52.30 | 50.80 | 4 | 25.40 | 101.6 | 3.74 | |
| 11/4 | 42.20 | 158.7 | 28.40 | 73.15 | 42.20 | 63.50 | 63.50 | 4 | 25.40 | 111.2 | 4.33 | |
| 11/2 | 48.30 | 177.8 | 31.70 | 82.50 | 48.30 | 69.85 | 73.15 | 4 | 28.40 | 123.9 | 5.94 | |
| 2 | 60.30 | 215.9 | 38.10 | 101.6 | 60.45 | 104.6 | 91.90 | 8 | 25.40 | 165.1 | 10.8 | |
| 21/2 | 73.00 | 244.3 | 41.10 | 104.6 | 73.15 | 123.9 | 104.6 | 8 | 28.40 | 190.5 | 15.0 | |
| 3 | 88.90 | 241.3 | 38.10 | 101.6 | 88.90 | 127.0 | 127.0 | 8 | 25.40 | 190.5 | 13.7 | |
| 4 | 114.3 | 292.1 | 44.40 | 114.3 | 114.3 | 158.7 | 157.2 | 8 | 31.70 | 234.9 | 22.5 | |
| 5 | 141.3 | 349.2 | 50.80 | 127.0 | 141.2 | 190.5 | 185.7 | 8 | 35.00 | 279.4 | 37.4 | |
| 6 | 168.3 | 381.0 | 55.60 | 139.7 | 168.4 | 234.9 | 215.9 | 12 | 31.70 | 317.5 | 47.7 | |
| 8 | 219. 1 | 469.9 | 63.50 | 162.0 | 219.2 | 298.4 | 269.7 | 12 | 38.10 | 393.7 | 81.3 | |
| 10 | 273.0 | 546.1 | 69.85 | 184. 1 | 273.0 | 368.3 | 323.8 | 16 | 38.10 | 469.9 | 119 | |
| 12 | 323.8 | 609.6 | 79.25 | 200. 1 | 323.8 | 419.1 | 381.0 | 20 | 38.10 | 533.4 | 157 | |
| 14 | 355.6 | 641.3 | 85.80 | 212.8 | 355.6 | 450.8 | 412.7 | 20 | 41.10 | 558.8 | 180 | |
| 16 | 406.4 | 704.8 | 88.90 | 215.9 | 406.4 | 508.0 | 469.9 | 20 | 44.40 | 615.9 | 217 | |
| 18 | 457.2 | 787.4 | 101.6 | 228.6 | 457.2 | 565.1 | 533.4 | 20 | 50.80 | 685.8 | 292 | |
| 20 | 508.0 | 857.2 | 107.9 | 247.6 | 508.0 | 622.3 | 584.2 | 20 | 53.80 | 749.3 | 362 | |
| 24 | 609.6 | 1041.4 | 139.7 | 292. 1 | 609.6 | 749.3 | 692.1 | 20 | 66.55 | 901.7 | 665 | |
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 120.6 | To be specified by the Purchaser | 22.30 | 60.45 | 21.30 | 38.10 | 35.00 | 4 | 22.30 | 82.50 | 1.87 |
| 3/4 | 26.70 | 130.0 | 25.40 | 69.85 | 26.70 | 44.00 | 42.90 | 4 | 22.30 | 88.90 | 2.56 | |
| 1 | 33.40 | 149.3 | 28.40 | 73.15 | 33.50 | 52.30 | 50.80 | 4 | 25.40 | 101.6 | 3.74 | |
| 11/4 | 42.20 | 158.7 | 28.40 | 73.15 | 42.20 | 63.50 | 63.50 | 4 | 25.40 | 111.2 | 4.33 | |
| 11/2 | 48.30 | 177.8 | 31.70 | 82.50 | 48.30 | 69.85 | 73. 15 | 4 | 28.40 | 123.9 | 5.94 | |
| 2 | 60.30 | 215.9 | 38.10 | 101.6 | 60.45 | 104.6 | 91.90 | 8 | 25.40 | 165.1 | 10.8 | |
| 21/2 | 73.00 | 244.3 | 41.10 | 104.6 | 73.15 | 123.9 | 104.6 | 8 | 28.40 | 190.5 | 15.0 | |
| 3 | 88.90 | 266.7 | 47.70 | 177.3 | 88.9 | 133.3 | 127.0 | 8 | 31.70 | 203.2 | 19.9 | |
| 4 | 114.3 | 311.1 | 53.80 | 123.9 | 114.3 | 162.0 | 157.2 | 8 | 35.00 | 241.3 | 29.9 | |
| 5 | 141.3 | 374.6 | 73.15 | 155.4 | 141.2 | 196.8 | 185.7 | 8 | 41.10 | 292.1 | 55.4 | |
| 6 | 168.3 | 393.7 | 82.50 | 171.4 | 168.4 | 228.6 | 215.9 | 12 | 38.10 | 317.5 | 68.4 | |
| 8 | 219.1 | 482.6 | 91.90 | 212.8 | 219.2 | 292.1 | 269.7 | 12 | 44.40 | 393.7 | 117 | |
| 10 | 273.0 | 584.2 | 107.9 | 254.0 | 273.0 | 368.3 | 323.8 | 12 | 50.80 | 482.6 | 194 | |
| 12 | 323.8 | 673. 1 | 123.9 | 282.4 | 323.8 | 450.8 | 381.0 | 16 | 53.80 | 571.5 | 288 | |
| 14 | 355.6 | 749.3 | 133.3 | 298.4 | 355.6 | 495.3 | 412.7 | 16 | 60.45 | 635.0 | 380 | |
| 16 | 406.4 | 825.5 | 146.0 | 311. 1 | 406.4 | 552.4 | 469.9 | 16 | 66.55 | 704.8 | 485 | |
| 18 | 457.2 | 914.4 | 162.0 | 327.1 | 457.2 | 596.9 | 533.4 | 16 | 73.15 | 774.7 | 644 | |
| 20 | 508.0 | 984.2 | 177.8 | 355.6 | 508.0 | 641.3 | 584.2 | 16 | 79.25 | 831.8 | 775 | |
| 24 | 609.6 | 1168.4 | 203.2 | 406.4 | 609.6 | 762.0 | 692.1 | 16 | 91.90 | 990.6 | 1232 | |
| Nominal Pipe Size | A | B | C | D | E | F | G | H | I | J | Weight | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm | kg / piece |
| 1/2 | 21.30 | 133.4 | To be specified by the Purchaser | 30.20 | 73. 15 | 21.30 | 42.90 | 35.00 | 4 | 22.40 | 88.90 | 3.12 |
| 3/4 | 26.70 | 139.7 | 31.75 | 79.25 | 26.70 | 50.80 | 42.90 | 4 | 22.40 | 95.30 | 3.70 | |
| 1 | 33.40 | 158.8 | 35.10 | 88.90 | 33.50 | 57.15 | 50.80 | 4 | 25.40 | 108.0 | 5.24 | |
| 11/4 | 42.20 | 184.2 | 38.10 | 95.30 | 42.20 | 73.15 | 63.50 | 4 | 28.40 | 130.0 | 7.74 | |
| 11/2 | 48.30 | 203.2 | 44.50 | 111.3 | 48.30 | 79.25 | 73.15 | 4 | 31.75 | 146. 1 | 10.9 | |
| 2 | 60.30 | 235.0 | 50.80 | 127.0 | 60.45 | 95.30 | 91.90 | 8 | 28.40 | 171.5 | 16.2 | |
| 21/2 | 73.00 | 266.7 | 57.15 | 142.7 | 73.15 | 114.3 | 104.6 | 8 | 31.75 | 196.9 | 23.7 | |
| 3 | 88.90 | 304.8 | 66.55 | 168.1 | 88.90 | 133.4 | 127.0 | 8 | 35.10 | 228.6 | 36.2 | |
| 4 | 114.3 | 355.6 | 76.20 | 190.5 | 114.3 | 165.1 | 157.2 | 8 | 41.10 | 273. 1 | 55.3 | |
| 5 | 141.3 | 419.1 | 91.90 | 228.6 | 141.2 | 203.2 | 185.7 | 8 | 47.80 | 323.9 | 92.5 | |
| 6 | 168.3 | 482.6 | 108 | 273.1 | 168.4 | 235.0 | 215.9 | 8 | 53.80 | 368.3 | 143 | |
| 8 | 219.1 | 552.5 | 127.0 | 317.5 | 219.2 | 304.8 | 269.7 | 12 | 53.80 | 438.2 | 215 | |
| 10 | 273.0 | 673.1 | 165.1 | 419.1 | 273.0 | 374.7 | 323.8 | 12 | 66.55 | 539.8 | 406 | |
| 12 | 323.8 | 762.0 | 184.2 | 463.6 | 323.8 | 441.5 | 381.0 | 12 | 73.15 | 619.3 | 572 | |
ASTM A182/A182M is the core specification for forged stainless steel flanges, fittings, valves, and parts for high-temperature service. It covers ferritic, martensitic, austenitic, and duplex (ferritic-austenitic) grades.
Maximum forging weight is 10,000 lb (≈4,540 kg). Materials must meet chemical composition, tensile strength, yield strength, elongation, and hardness requirements.
Austenitic grades offer good corrosion resistance, ductility, and weld ability.
F304 (UNS S30400) is a general-purpose, cost-effective choice for mild corrosive environments.
F304L (S30403) has extra-low carbon (≤0.03%) for better resistance to intergranular corrosion after welding without post-weld heat treatment.
F316 (S31600) contains molybdenum (2–3%), improving pitting and crevice corrosion resistance in chloride media like seawater.
F316L (S31603) combines F316's corrosion resistance with F304L's weldability, making it the most widely used grade for corrosive flange applications.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo |
| ASTM A403 WP304 | MIN | 8.0 | 18.0 | ||||||
| MAX | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 11.0 | 20.0 | ||
| ASTM A403 WP304L | MIN | 8.0 | 18.0 | ||||||
| MAX | 0.03 | 2.00 | 0.045 | 0.030 | 1.00 | 11.0 | 20.0 | ||
| ASTM A403 WP316 | MIN | 10.00 | 16.00 | 2.00 | |||||
| MAX | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 14.00 | 18.00 | 3.00 | |
| ASTM A403 WP316L | MIN | 10.00 | 16.00 | 2.00 | |||||
| MAX | 0.03 | 2.00 | 0.045 | 0.030 | 1.00 | 14.00 | 18.00 | 3.00 |
Mechanical Properties
| MATERIAL | ASTM A182 F304 | ASTM A182 F304L | ASTM A182 F316 | ASTM A182 F316L |
| T.S (MPA) | 515 min | 485 min | 515 min | 485 min |
| Y.S (MPA) | 205 min | 170 min | 205 min | 170 min |
| EL % | 30 min | 30 min | 30 min | 30 min |
| R/A % | 50 min | 50 min | 50 min | 50 min |
Duplex steels consist of roughly 50% ferrite and 50% austenite, offering yield strength about twice that of austenitic grades, plus excellent resistance to chloride stress corrosion cracking.
F51 (S31803, 2205) is the most common duplex grade, widely used in petrochemical, marine, and FGD systems.
F53 (S32750, 2507 super duplex) and F55 (S32760, Zeron 100) have PREN values ≥40, ideal for seawater desalination, offshore platforms, and deep-sea equipment. Higher PREN means better pitting resistance.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo | N | Cu | W |
| ASTM A182 F51 | MIN | 4.50 | 21.00 | 2.50 | 0.08 | |||||||
| MAX | 0.03 | 2.00 | 0.030 | 0.020 | 1.00 | 6.50 | 23.00 | 3.50 | 0.20 | |||
| ASTM A182 F53 | MIN | 6.00 | 24.00 | 3.00 | 0.24 | |||||||
| MAX | 0.03 | 1.20 | 0.035 | 0.020 | 0.80 | 8.00 | 26.00 | 5.00 | 0.32 | 0.50 | ||
| ASTM A182 F55 | MIN | 6.00 | 24.00 | 3.00 | 0.20 | 0.50 | 0.50 | |||||
| MAX | 0.03 | 1.00 | 0.030 | 0.010 | 1.00 | 8.00 | 26.00 | 4.00 | 0.30 | 1.00 | 1.00 |
Mechanical Properties
| MATERIAL | ASTM A182 F51 | ASTM A182 F53 | ASTM A182 F55 |
| T.S (MPA) | 620 min | 800 min | 750-895 |
| Y.S (MPA) | 450 min | 550 min | 550 min |
| EL % | 15 min | 25 min | 25 min |
| R/A % | 15 min | 45 min | |
| HARDNESS | 310 max |
F304/F304L: General chemical, food processing, and plumbing services, from –196°C to 800°C. Choose 304L when welding without post-weld heat treatment.
F316/F316L: For chloride-bearing environments like seawater cooling, papermaking, pharmaceuticals, and fine chemicals. Prefer 316L for welded assemblies without heat treatment.
F51 (2205): Medium-to-high pressure, high-chloride, and strength-demanding services such as offshore structural piping, oil/gas gathering lines, and flue gas desulfurization. Its yield strength (≥450 MPa) allows thinner, lighter flanges.
F53/F55: Extremely corrosive conditions—deep-sea oil extraction, high-pressure seawater lines, concentrated chloride chemicals, and hot seawater heat exchangers. These require strict welding heat input control and skilled operators.
Ensure the flange meets ASME B16.5 dimensions, tolerances, and pressure-temperature ratings.
Choose the ASTM A182 grade based on media corrosiveness, temperature, and design pressure—austenitic for general use, duplex for high strength and chloride resistance.
For high pressure or critical services, request additional NDT per ASTM A182 Supplementary Requirements.
Always ask for a Material Test Certificate (MTC) to confirm full traceability, chemistry, and mechanical properties.
